Frederick II, Holy Roman Emperor

Frederick II
Emperor of the Romans
Contemporary portrait of Frederick II from the "Manfred manuscript" (Biblioteca Vaticana, Pal. lat 1071) of De arte venandi cum avibus
Holy Roman Emperor King of Germany and Italy
Reign	23 November 1220 – 13 December 1250
Coronation	9 December 1212 (Mainz, German coronation) 22 November 1220 (Rome, Papal Coronation)
Predecessor	Otto IV in 1215
Successor	Henry (VII) king in 1220
King of Sicily
Reign	1198–1250
Coronation	3 September 1198, Palermo
Predecessor	Constance I
Successor	Conrad I
Co-rulers	Constance I (1198) Henry II (1212–1217)
King of Jerusalem
Reign	1225–1228
Coronation	18 March 1229, Jerusalem
Predecessor	Isabella II and John
Successor	Conrad II
Co-ruler	Isabella II
Born	26 December 1194 Jesi, March of Ancona, Italy
Died	13 December 1250(1250-12-13) (aged 55) Castel Fiorentino, Kingdom of Sicily
Burial	Cathedral of Palermo
Spouses	Constance of Aragon ​ ​ (m. 1209; died 1222)​ Isabella II of Jerusalem ​ ​ (m. 1225; died 1228)​ Isabella of England ​ ​ (m. 1235; died 1241)​ Bianca Lancia ​ (m. 1246)​
Issue more...	Henry VII, King of Germany Conrad IV, King of Germany Margaret, Landgravine of Thuringia Illegitimate: Frederick of Pettorano Enzo, King of Sardinia Frederick, Imperial Vicar of Tuscany Anna, Empress of Nicaea Manfred, King of Sicily
House	Hohenstaufen
Father	Henry VI, Holy Roman Emperor
Mother	Constance I of Sicily

Frederick II (Italian: Federico; German: Friedrich; Latin: Fridericus; 26 December 1194 – 13 December 1250) was King of Sicily from 1198, King of Germany from 1212, King of Italy and Holy Roman Emperor from 1220 and King of Jerusalem from 1225. He was the son of Emperor Henry VI of the Hohenstaufen dynasty (the second son of Emperor Frederick Barbarossa) and Queen Constance I of Sicily of the Hauteville dynasty.

He was one of the most powerful figures of the Middle Ages and ruled a vast area, beginning with Sicily and stretching through Italy all the way north to Germany. As the Crusades progressed, he acquired control of Jerusalem and styled himself its king. Viewing himself as a direct successor to the Roman emperors of antiquity, he was Emperor of the Romans from his papal coronation in 1220 until his death; he was also a claimant to the title of King of the Romans from 1212 and unopposed holder of that monarchy from 1215. As such, he was King of Germany, of Italy, and of Burgundy. At the age of three, he was crowned King of Sicily as a co-ruler with his mother, Constance, Queen of Sicily, the daughter of Roger II of Sicily. His other royal title was King of Jerusalem by virtue of marriage and his connection with the Sixth Crusade. Frequently at war with the papacy, which was hemmed in between Frederick's lands in northern Italy and his Kingdom of Sicily (the Regno) to the south, he was "excommunicated four times between 1227 and his own death in 1250", and was often vilified in pro-papal chronicles of the time and after. Pope Gregory IX went so far as to declare him preambulus Antichristi (predecessor of the Antichrist).

For his many-sided activities and dynamic personality Frederick II has been called the greatest of all the medieval German emperors. In the Kingdom of Sicily and much of Italy, Frederick built upon the work of his Norman predecessors and forged an early absolutist state bound together by an efficient secular bureaucracy. He was known by the appellation stupor mundi or the “wonder of the world” and enjoys a reputation as a brilliant Renaissance man avant la lettre and polymath: a visionary statesman, scientist, scholar, mathematician, architect, poet and composer. Frederick also reportedly spoke six languages: Latin, Sicilian, Middle High German, Old French, Greek, and Arabic. As an avid patron of science and the arts, he played a major role in promoting literature through the Sicilian School of poetry. His magnificent Sicilian imperial-royal court in Palermo and, more particularly, Foggia, beginning around 1220, saw the first use of a literary form of an Italo-Romance language, Sicilian. The poetry that emanated from the school had a significant influence on literature and on what was to become the modern Italian language. He was also the first monarch to formally outlaw trial by ordeal, which had come to be viewed as superstitious.

Though still in a strong position at his death, his line did not long survive, and the House of Hohenstaufen came to an end. Furthermore, the Holy Roman Empire entered a long period of decline during the Great Interregnum. His complex political and cultural legacy has attracted fierce debates and fascination until this day.

Birth and naming

The birth of Frederick on the market square of Jesi from the Nuova Cronica, Biblioteca Apostolica Vaticana, ms. Chigi L. VIII.296 (cat. XI.8)

Born in Jesi, near Ancona, Italy, on 26 December 1194, Frederick was the son of Henry VI, Holy Roman Emperor. He was known as the puer Apuliae (son of Apulia). His mother was Constance of Sicily. Frederick was baptised in Assisi, in the church of San Rufino.

At birth, Frederick was named Constantine by his mother. This name, a masculine form of his mother's name, served to identify him closely with both his Norman heritage and his imperial heritage (through Constantine the Great, the first Christian emperor). It was still his name at the time of his election as King of the Romans. He was only given his grandfathers' names, becoming Frederick Roger (or Roger Frederick), at his baptism when he was two years old. This dual name served the same purpose as Constantine: emphasising his dual heritage.

Frederick's birth was accompanied by gossip and rumour on account of his mother's advanced age. According to Albert of Stade and Salimbene, he was not the son of Henry and Constance but was presented to Henry as his own after a faked pregnancy. His real father was variously described as a butcher of Jesi, a physician, a miller or a falconer. Frederick's birth was also associated with a prophecy of Merlin. According to Andrea Dandolo, writing at some distance but probably recording contemporary gossip, Henry doubted reports of his wife's pregnancy and was only convinced by consulting Joachim of Fiore, who confirmed that Frederick was his son by interpretation of Merlin's prophecy and the Erythraean Sibyl. A later legend claims that Constance gave birth in the public square of Jesi to silence doubters. Constance took unusual measures to prove her pregnancy and its legitimacy and Roger of Howden reports that she swore on the gospels before a papal legate that Frederick was her son by Henry. It is probable that these public acts of affirmation on account of her age gave rise to some false rumours.

In the spring of 1195, a few months after Henry VI had been crowned king of Sicily and not long after the birth of her son, Constance the empress continued her journey to Palermo. After the unexpected death of Tancred of Lecce (an illegitimate son of Roger, eldest son of Roger II of Sicily) Henry had hurried over to assume power and to have himself crowned king. Frederick was entrusted to the care of the duchess of Spoleto, the wife of the Swabian noble Conrad I of Urslingen, who was named duke of Spoleto by Frederick Barbarossa. Frederick II stayed in Foligno, a place located in papal territory and so under papal jurisdiction, until the death of his father, on September 28 in 1197.

Minority

Constance handing her son over to the care of the duchess of Spoleto, the wife of Conrad of Urslingen, from the Liber ad honorem Augusti by Peter of Eboli

In 1196 at Frankfurt am Main the infant Frederick was elected King of the Romans and thus heir to his father's imperial crown. His rights in Germany were to end up disputed by Henry's brother Philip of Swabia and Otto of Brunswick. At the death of his father Henry VI in 1197, Frederick was in Italy, traveling towards Germany, when the bad news reached his guardian, Conrad of Spoleto. Frederick was hastily brought back to his mother Constance in Palermo, Sicily, where he was crowned King of Sicily on 17 May 1198, at just three years of age. Originally his title had been Romanorum et Sicilie rex (King of the Romans and Sicily), but in 1198, after Constance (who kept using title of Empress) found out that Philip of Swabia had been recognized by the Staufer supporters in Germany, she had her son renounce the title King of the Romans. She probably agreed with Philip that Frederick's prospects in Germany were hopeless. The decision strengthened Frederick's position in Sicily as this satisfied both Philip of Swabia and the Pope, who did not like the idea of a ruler who had authority in both Sicily and the North Alpine realm.

Constance of Sicily was in her own right queen of Sicily, and she established herself as regent. Constance sided with the Pope who preferred that Sicily and the Germans were under separate governments. She renounced the authority over the Sicilian state church to the papal side, but only as Sicilian queen and not as empress, seemingly with the intention of keeping options open for Frederick. Upon Constance's death in 1198, Pope Innocent III succeeded as Frederick's guardian. Frederick's tutor during this period was Cencio, who would become Pope Honorius III. Markward of Annweiler, with the support of Henry's brother, Philip of Swabia, reclaimed the regency for himself and soon after invaded the Kingdom of Sicily. In 1200, with the help of Genoese ships, he landed in Sicily and one year later seized the young Frederick. He thus ruled Sicily until 1202, when he was succeeded by another German captain, William of Capparone, who kept Frederick under his control in the royal palace of Palermo until 1206. Frederick was subsequently under tutor Walter of Palearia, until, in 1208, he was declared of age. At that time he spoke five languages, Greek, Arabic, Latin, Provençal and Sicilian. His first task was to reassert his power over Sicily and southern Italy, where local barons and adventurers had usurped most of the authority. Pope Innocent was in search of a diplomatic match for his protege Frederick, to enable him successful future alliances. Eventually Constance of Aragon, a widow of the late King of Hungary and double his age was found.

Securing the Imperial Crown

Seals used by Frederick as Emperor (ed. Otto Posse 1909): 1: first imperial seal (1221–1225), 2: second imperial seal (1226), 3: third imperial seal, addition of the title of King of Jerusalem (1226–1250) 4: seal used in 1221 and 1225, 5: first seal as King of Jerusalem (1233).

Otto of Brunswick had been crowned Holy Roman Emperor by Pope Innocent III in October 1209. In southern Italy, Otto became the champion of those noblemen and barons who feared Frederick's increasingly strong measures to check their power, such as the dismissal of the pro-noble Walter of Palearia. The new emperor invaded Italy, where he reached Calabria without meeting much resistance.

In response, Innocent sided against Otto, and in September 1211 at the Diet of Nuremberg Frederick was elected in absentia as German King by a rebellious faction backed by the pope. Innocent also excommunicated Otto, who was forced to return to Germany. Frederick sailed to Gaeta with a small following. He agreed with the pope on a future separation between the Sicilian and Imperial titles, and named his wife Constance as regent. Passing through Lombardy and Engadin, he reached Konstanz in September 1212, preceding Otto by a few hours.

Frederick was crowned king on 9 December 1212 in Mainz. Frederick's authority in Germany remained tenuous, and he was recognized only in southern Germany. In the region of northern Germany, the center of Guelph power, Otto continued to hold the reins of royal and imperial power despite his excommunication. Otto's decisive military defeat at the Bouvines forced him to withdraw to the Guelph hereditary lands where, virtually without supporters, he died in 1218.

The German princes, supported by Innocent III, again elected Frederick king of Germany in 1215, and he was crowned king in Aachen in mid-July 1215 by one of the three German archbishops. Frederick then astonished the crowd by taking the cross and calling upon the nobles present to do the same. It was not until another five years had passed, and only after further negotiations between Frederick, Innocent III, and Honorius III – who succeeded to the papacy after Innocent's death in 1216 – that Frederick was crowned Holy Roman Emperor in Rome by Honorius III, on 22 November 1220. At the same time, Frederick's oldest son Henry took the title of King of the Romans.

Unlike most Holy Roman emperors, Frederick spent few years in Germany. In 1218, he helped King Philip II of France and Odo III, Duke of Burgundy, to bring an end to the War of Succession in Champagne (France) by invading Lorraine, capturing and burning Nancy, capturing Theobald I, Duke of Lorraine and forcing him to withdraw his support from Erard of Brienne-Ramerupt. After his coronation in 1220, Frederick remained either in the Kingdom of Sicily or on Crusade until 1235, when he made his last journey to Germany. He returned to Italy in 1237 and stayed there for the remaining thirteen years of his life, represented in Germany by his son Conrad.

In the Kingdom of Sicily, he built on the reform of the laws begun at the Assizes of Ariano in 1140 by his grandfather Roger II. His initiative in this direction was visible as early as the Assizes of Capua (1220, issued soon after his coronation in Rome) but came to fruition in his promulgation of the Constitutions of Melfi (1231, also known as Liber Augustalis), a collection of laws for his realm that was remarkable for its time and was a source of inspiration for a long time after. It made the Kingdom of Sicily an absolutist monarchy; it also set a precedent for the primacy of written law. With relatively small modifications, the Liber Augustalis remained the basis of Sicilian law until 1819.

In 1223–1224, Frederick tried Bishop Aldoin of Cefalù for maladministration. The trial was nullified by the pope on procedural grounds.

Worried by the independent rule the Muslim population developed since his departure in 1212, he deported the Muslim population of Sicily to Lucera on mainland Italy between 1220-1223. In Lucera he assumed, surveillance was better in order to control them and the Muslims acknowledged that they were left with their religious freedom. He also enlisted some in the army and six hundred as his personal bodyguards because, as Muslim soldiers, they had the advantage of immunity from papal excommunication.

Foreign policy and wars

The Fifth Crusade and early policies in northern Italy

Main article: Fifth Crusade

At the time he was elected King of the Romans, Frederick promised to go on crusade. He continually delayed, however, and, in spite of his renewal of this vow at his coronation as the King of Germany, he did not travel to Egypt with the armies of the Fifth Crusade in 1217. He sent forces to Egypt under the command of Louis I, Duke of Bavaria, but constant expectation of his arrival caused papal legate Pelagius to reject Ayyubid sultan Al-Kamil's offer to restore the Latin Kingdom of Jerusalem to the crusaders in exchange for their withdrawal from Egypt and caused the Crusade to continually stall in anticipation of his ever-delayed arrival. The crusade ended in failure with the loss of Damietta in 1221. Frederick was blamed by both Pope Honorius III and the general Christian populace for this calamitous defeat.

In 1225, after agreeing with Pope Honorius to launch a Crusade before 1228, Frederick summoned an imperial Diet at Cremona, the main pro-imperial city in Lombardy: the main arguments for holding the Diet would be to continue the struggle against heresy, to organize the crusade and, above all, to restore the imperial power in northern Italy, which had long been usurped by the numerous communes located there. Those assembled responded with the reformation of the Lombard League, which had already defeated his grandfather Frederick Barbarossa in the 12th century, and again Milan was chosen as the league's leader. The Diet was cancelled, however, and the situation was stabilized only through a compromise reached by Honorius between Frederick and the league. During his sojourn in northern Italy, Frederick also invested the Teutonic Order with the territories in what would become East Prussia, starting what was later called the Northern Crusade.

Frederick was distracted with the League when in June 1226 Louis VIII of France laid siege to Avignon, an imperial city. The barons of the French army sent a letter to Frederick defending their action as a military necessity, and a few days after the start of the siege Henry (VII) ratified an alliance with France that had been signed in 1223.

The Sixth Crusade

Main article: Sixth Crusade

Frederick II (left) meets Al-Kamil (right). Nuova Cronica, c. 1348

Problems of stability within the empire delayed Frederick's departure on crusade. It was not until 1225, when, by proxy, Frederick had married Isabella II of Jerusalem, heiress to the Kingdom of Jerusalem, that his departure seemed assured. Frederick immediately saw to it that his new father-in-law John of Brienne, the current king of Jerusalem, was dispossessed and his rights transferred to the emperor. In August 1227, Frederick set out for the Holy Land from Brindisi but was forced to return when he was struck down by an epidemic that had broken out. Even the master of the Teutonic Knights, Hermann of Salza, recommended that he return to the mainland to recuperate. On 29 September 1227, Frederick was excommunicated by Pope Gregory IX for failing to honor his crusading pledge.

Many contemporary chroniclers doubted the sincerity of Frederick's illness, and their attitude may be explained by their pro-papal leanings. Roger of Wendover, a chronicler of the time, wrote that Frederick:

went to the Mediterranean sea, and embarked with a small retinue; but after pretending to make for the Holy Land for three days, he said that he was seized with a sudden illness [...] this conduct of the emperor redounded much to his disgrace, and to the injury of the whole business of the crusade.

Frederick eventually sailed again from Brindisi in June 1228. The pope, still Gregory IX, regarded that action as a provocation, since, as an excommunicate, Frederick was technically not capable of conducting a crusade, and he excommunicated the emperor a second time. Frederick reached Acre in September. Many of the local nobility, the Templars, and Hospitallers were therefore reluctant to offer overt support. Since the crusading army was already a small force, Frederick negotiated along the lines of a previous agreement he had intended to broker with the Ayyubid sultan, Al-Kamil. The treaty, signed in February 1229, resulted in the restitution of Jerusalem, Nazareth, Bethlehem, and a small coastal strip to the Kingdom of Jerusalem, though there are disagreements as to the extent of the territory returned.

The treaty also stipulated that the Dome of the Rock and al-Aqsa Mosque were to remain under Muslim control and that the city of Jerusalem would remain without fortifications. Virtually all other crusaders, including the Templars and Hospitallers, condemned this deal as a political ploy on the part of Frederick to regain his kingdom while betraying the cause of the Crusaders. Al-Kamil, who was nervous about possible war with his relatives who ruled Syria and Mesopotamia, wished to avoid further trouble from the Christians, at least until his domestic rivals were subdued.

The crusade ended in a truce and in Frederick's coronation as King of Jerusalem on 18 March 1229, although this was technically improper. Frederick's wife Isabella, the heiress, had died, leaving their infant son Conrad as rightful king. There is also disagreement as to whether the "coronation" was a coronation at all, as a letter written by Frederick to Henry III of England suggests that the crown he placed on his own head was in fact the imperial crown of the Romans.

At his coronation, he may have worn the red silk mantle that had been crafted during the reign of Roger II. It bore an Arabic inscription indicating that the robe dated from the year 528 in the Muslim calendar, and incorporated a generic benediction, wishing its wearer "vast prosperity, great generosity and high splendor, fame and magnificent endowments, and the fulfillment of his wishes and hopes. May his days and nights go in pleasure without end or change." This coronation robe can be found today in the Schatzkammer of the Kunsthistorisches Museum in Vienna.

In any case, Gerald of Lausanne, the Latin Patriarch of Jerusalem, did not attend the ceremony; indeed, the next day the Bishop of Caesarea arrived to place the city under interdict on the patriarch's orders. Frederick's further attempts to rule over the Kingdom of Jerusalem were met by resistance on the part of the barons, led by John of Ibelin, Lord of Beirut. In the mid-1230s, Frederick's viceroy was forced to leave Acre, and in 1244, following a siege, Jerusalem itself was lost again to a new Muslim offensive.

Whilst Frederick's seeming bloodless recovery of Jerusalem for the cross brought him great prestige in some European circles, his decision to complete the crusade while excommunicated provoked Church hostility. Although in 1230 the Pope lifted Frederick's excommunication, this decision was taken for a variety of reasons related to the political situation in Europe. Of Frederick's crusade, Philip of Novara, a chronicler of the period, said: "The emperor left Acre [after the conclusion of the truce]; hated, cursed, and vilified." Overall this crusade, arguably the first successful one since the First Crusade, was adversely affected by the manner in which Frederick carried out negotiations without the support of the church. He left behind a kingdom in the Levant torn between his agents and the local nobility, a civil war known as the War of the Lombards.

The itinerant Joachimite preachers and many radical Franciscans, the Spirituals, supported Frederick. Against the interdict pronounced on his lands, the preachers condemned the Pope and continued to minister the sacraments and grant absolutions. Brother Arnold in Swabia proclaimed the Second Coming for 1260, at which time Frederick would then confiscate the riches of Rome and distribute them among the poor, the "only true Christians".

War of the Keys

Main article: War of the Keys

Frederick II's statue in Palazzo Reale di Napoli by Emanuele Caggiano (1888).

During Frederick's stay in the Holy Land, his regent, Rainald of Spoleto, had attacked the March of Ancona and the Duchy of Spoleto. Gregory IX recruited an army under John of Brienne and, in 1229, invaded southern Italy. His troops overcame an initial resistance at Montecassino and reached into Campania as far as the Volturno–Irpino. Frederick arrived at Brindisi in June 1229. He quickly recovered the lost territories, and tried and condemned the rebel barons, but avoided crossing the borders of the Papal States.

The war came to an end with the Treaty of San Germano in July 1230. On 28 August, in a public ceremony in Ceprano, the papal legates Thomas of Capua and Giovanni Colonna absolved Frederick and lifted his excommunication. The emperor personally met Gregory IX at Anagni, making some concessions to the church in Sicily. He also issued the Constitutions of Melfi (August 1231) to solve the political and administrative problems of the country, which had dramatically been shown by the recent war.

Henry's revolt

While he may have temporarily made his peace with the pope, Frederick found the German princes another matter. Frederick's son Henry VII (who was born 1211 in Sicily, son of Frederick's first wife Constance of Aragon) had caused their discontent with an aggressive policy against their privileges. This forced Henry to a complete capitulation, and the Statutum in favorem principum ("Statute in favor of the princes"), issued at Worms, deprived the emperor of much of his sovereignty in Germany. Frederick summoned Henry to a meeting, which was held at Aquileia in 1232. Henry confirmed his submission, but Frederick was nevertheless compelled to confirm the Statutum at Cividale soon afterwards.

The situation for Frederick was also problematic in Lombardy, after all the emperor's attempts to restore the imperial authority in Lombardy with the help of Gregory IX (at the time, ousted from Rome by a revolt) turned to nothing in 1233. In the meantime Henry in Germany had returned to an anti-princes policy, against his father's will: Frederick thus obtained his excommunication from Gregory IX (July 1234). Henry tried to muster an opposition in Germany and asked the Lombard cities to block the Alpine passes. In May 1235, Frederick went to Germany, taking with him no anrmy, only a sumptuous entourage as a display of his power and wealth. News of his arrival spread quickly and the rebellion disintegrated. As soon as July, he was able to force his son to renounce the crown and all his lands at Worms, where Henry was tried and imprisoned. Henry remained a prisoner in Apulia for the rest of his life until he reportedly committed suicide. Frederick II skillfully turned the complex challenge of Henry’s rebellion into a chance to introduce “thorough and groundbreaking” reform of Germany and the way the empire was ruled. The Mainz Landfriede or Constitutio Pacis, decreed at the Imperial Diet of 1235, became one of the basic laws of the empire and provided that the princes should share the burden of local government in Germany. It was a testament to Frederick’s considerable political strength, his increased prestige during the early 1230s, and sheer overpowering might that he succeeded in securing their support and rebound them to Hohenstaufen power.

In Germany the Hohenstaufen and the Guelphs reconciled in 1235. Otto the Child, the grandson of Henry the Lion, had been deposed as Duke of Bavaria and Saxony in 1180, conveying the allodial Guelphic possessions to Frederick, who in return enfeoffed Otto with the same lands and additional former imperial possessions as the newly established Duke of Brunswick-Lüneburg, ending the unclear status of the German Guelphs, who had been left without title and rank after 1180, and encouraging their cooperation.

The war for Lombardy and Italy

The Battle of Cortenuova against the 2nd Lombard League (1237), Nuova Cronica c. 1348

Frederick II's troops paid with leather coins during the Siege of Faenza, Nuova Cronica c. 1348

The Battle of Giglio against Gregory IX in 1241, Chronica Maiora (1259)

With peace north of the Alps, Frederick raised an army from the German princes to suppress the rebel cities in Lombardy. Gregory tried to stop the invasion with diplomatic moves, but in vain. During his descent to Italy, Frederick had to divert his troops to quell a rebellion of Frederick II, Duke of Austria. At Vienna, in February 1237, he obtained the title of King of the Romans for his 9-year-old son Conrad.

After the failure of the negotiations between the Lombard cities, the pope and the imperial diplomats, Frederick invaded Lombardy from Verona. In November 1237 he won the decisive battle in Cortenuova over the Lombard League, displaying his capability as a battlefield leader, able to maneuver and prevail in difficult situations. Frederick celebrated the victory with a triumph in Cremona in the manner of an ancient Roman emperor, with the captured carroccio (later sent to the commune of Rome) and an elephant. Now at the zenith of his power, Frederick’s political preeminence across all Europe was seemingly unassailable. Frederick rejected any suit for conditional peace from his Lombard enemies, even from Milan, his most implacable foe among the cities, which had sent a great sum of money. Perhaps from sober political calculation in light of years of Milanese opposition or simply hatred of the city, he was convinced that only complete military subjection could finally ensure imperial dominance. Frederick’s demand of total surrender spurred further resistance from Milan, Brescia, Bologna, and Piacenza. In the spring of 1238 Frederick summoned a vast international army to aid in his campaign against the remaining insurgent cities, gathering troops from England, France, Hungary, the Nicene Empire, and even a contingent sent by Muslim sultans in the east. From June, he besieged Brescia. After savage fighting in which the emperor himself was nearly captured, Frederick was surprised at the city’s continued defiance in the face of his large army and sent emissaries to negotiate its surrender. The Brescians rejected the emperor’s terms and the siege continued into September when torrential rains prevented any assault. After a last unsuccessful attack in October, Frederick was forced to raise the siege. Frederick’s prestige suffered a blow and the “legend of the emperor’s invincibility” had been damaged. Regrouping as the year closed, it was not Frederick’s political nous which failed him but a combination of bad luck and his incorrect assessment of the military resources required to subjugate the last few holdouts against imperial authority in northern Italy.

Gregory IX sensed vulnerability and Frederick received the news of his excommunication by the pope in the first months of 1239 while his court was in Padua. The emperor responded by expelling the Franciscans and the Dominicans from Lombardy, taking hostages from important northern Italian families, and electing his son Enzo as Legate General and Imperial vicar of Lombardy. Enzo soon annexed the Romagna, Marche, and the Duchy of Spoleto, nominally part of the Papal States. The emperor ordered Enzo to destroy the Republic of Venice, which had sent some ships against Sicily. In December of that year Frederick entered Tuscany and spent Christmas in Pisa. In January 1240, Frederick triumphantly entered Foligno followed by Viterbo, whence he aimed to finally conquer Rome to restore the ancient splendours of the Empire. Frederick's plan to attack Rome at that time, however, did not come to fruition as he chose to leave for southern Italy where a papal incited rebellion flared in Apulia. In southern Italy, Frederick attacked and razed the papal enclaves of St Angelo and Benevento.

In the meantime the Ghibelline city of Ferrara had fallen, and Frederick swept his way northwards capturing Ravenna and, after another long siege, Faenza. The people of Forlì, which had kept its Ghibelline stance even after the collapse of Hohenstaufen power, offered their loyal support during the capture of the rival city: as a sign of gratitude, they were granted an augmentation of the communal coat-of-arms with the Hohenstaufen eagle, together with other privileges. This episode shows how the independent cities used the rivalry between Empire and Pope as a means to obtain maximum advantage for themselves.

At this time, Gregory considered yielding. A truce occurred and peace negotiations began. Direct peace negotiations ultimately failed and Gregory called for a General Council. Frederick and his allies, however, dashed Gregory's plan for a General Council when they intercepted a delegation of prelates traveling to Rome in a Genoese fleet at the crushing Battle of Giglio (1241), capturing almost all of the high dignitaries and taking thousands of prisoners along with most of the fleet. The emperor proclaimed his victory to be divine judgment and a symbol against the illegality of his persecution by Gregory.

Frederick then directed his army toward Rome and the Pope, burning and destroying Umbria as he advanced. Then just as the Emperor's forces were ready to attack Rome, Gregory died on 22 August 1241. Frederick then attempted to show that the war was not directed against the Church of Rome but against the Pope by withdrawing his troops and freeing from prison in Capua two cardinals he had captured at Giglio, Otto of Tonengo and James of Pecorara. Frederick then traveled to Sicily to wait for the election of a new pope.

Mongol raids

Main article: Mongol incursions in the Holy Roman Empire

The Holy Roman Empire at the time of the Mongol incursions

In 1241–1242, the forces of the Mongol Empire decisively defeated the armies of Hungary and Poland and devastated their countryside and all their unfortified settlements. King Béla IV of Hungary appealed to Frederick for aid, but Frederick, being in dispute with the Hungarian king for some time (as Bela had sided with the Papacy against him) and not wanting to commit to a major military expedition so readily, refused. He was unwilling to cross into Hungary, and although he went about unifying his magnates and other monarchs to potentially face a Mongol invasion, he specifically took his vow for the defense of the empire on "this side of the Alps".

Frederick was aware of the danger the Mongols posed, and grimly assessed the situation, but also tried to use it as leverage over the Papacy to frame himself as the protector of Christendom. While he called them traitorous pagans, Frederick expressed an admiration for Mongol military prowess after hearing of their deeds, in particular their able commanders and fierce discipline and obedience, judging the latter to be the greatest source of their success. He called a levy throughout Germany while the Mongols were busy raiding Hungary. In mid-1241, Frederick dispersed his army back to their holdfasts as the Mongols preoccupied themselves with the lands east of the Danube, attempting to smash all Hungarian resistance. He subsequently ordered his vassals to strengthen their defenses, adopt a defensive posture, and gather large numbers of crossbowmen.

A chronicler reports that Frederick received a demand of submission from Batu Khan at some time, which he ignored. Frederick II apparently kept up to date on the Mongols' activities, as a letter from the emperor dated June 1241 comments that the Mongols were now using looted Hungarian armor. On 20 June in Faenza, the emperor issued the Encyclica contra Tartaros, an encyclical letter announcing the fall of Kiev, the invasion of Hungary and the threat to Germany, and requesting each Christian nation to devote its proper quota of men and arms to the defense of Christendom. According to Matthew of Paris's copy of the encyclical, it was addressed to the Catholic nations—France, Spain, Wales, Ireland, England, Swabia, Denmark, Italy, Burgundy, Apulia, Crete, Cyprus, Sicily, Scotland and Norway—each addressed according to its own national stereotype. Richard of San Germano states that copies were sent to all the princes of the West and quotes the start of the letter to the French king. In the encyclical, Frederick indicated he had accepted Hungarian submission as emperor. Another letter written by Frederick, found in the Regesta Imperii, dated to 20 June 1241, and intended for all his vassals in Swabia, Austria, and Bohemia, included a number of specific military instructions. His forces were to avoid engaging the Mongols in field battles, hoard all food stocks in every fortress and stronghold, and arm all possible levies as well as the general populace.

Thomas of Split comments that there was a frenzy of fortifying castles and cities throughout the Holy Roman Empire, including Italy. Either following the Emperor's instructions or on their own initiative, Frederick II, Duke of Austria paid to have his border castles strengthened at his own expense. King Wenceslaus I of Bohemia had every castle strengthened and provisioned, as well as providing soldiers and armaments to monasteries in order to turn them into refuges for the civilian population.

Mongol probing attacks materialised on the Holy Roman Empire's border states: a force was repulsed in a skirmish near Kłodzko, 300–700 Mongol troops were killed in a battle near Vienna to 100 Austrian losses (according to the Duke of Austria), and a Mongol raiding party was destroyed by Austrian knights in the district of Theben after being backed to the border of the River March. As the Holy Roman Empire seemed now the target of the Mongols, Frederick II sent letters to Henry III of England and Louis IX of France in order to organise a crusade against the Mongol Empire. A full-scale invasion never occurred, as the Mongols spent the next year pillaging Hungary before withdrawing. After the Mongols withdrew from Hungary back to Russia, Frederick turned his attention back towards Italian matters. The danger represented by the presence of the Mongols in Europe was debated again at the First Council of Lyon in 1245, but Frederick II was excommunicated by that very diet in the context of his struggle with the Papacy and ultimately abandoned the possibility of a crusade against the Mongol Empire.

Innocent IV

Main article: Ad Apostolicae Dignitatis Apicem

Excommunication of Frederick by Pope Innocent IV

A new pope, Innocent IV, was elected on 25 June 1243. He was a member of a noble Imperial family and had some relatives in Frederick's camp, so the Emperor was initially happy with his election. Innocent, however, was to become his fiercest enemy. Negotiations began in the summer of 1243, but the situation changed as Viterbo rebelled, instigated by the intriguing local cardinal Ranieri Capocci. Frederick could not afford to lose his main stronghold near Rome, so he besieged Viterbo.

Innocent IV convinced the rebels to sign a peace but, after Frederick withdrew his garrison, Ranieri had them slaughtered on 13 November. Frederick was enraged but signed a peace treaty, which was soon broken. The new pope was opposed to Frederick. Together with many of the Cardinals, most of whom were newly appointed by himself, Innocent fled via Genoese galleys to Liguria, arriving on 7 July. His aim was to reach Lyon, where a new church council was being held since 24 June 1245.

The council was under attended and despite initially appearing that it could end with a compromise, the intervention of Ranieri, who had a series of scurrilous pamphlets published against Frederick (in which, among other things, he defined the emperor as a heretic and an Antichrist), led the prelates towards a less accommodating solution. One month later, before Frederick’s representatives even reached Lyon, Innocent IV declared Frederick to be deposed as emperor, characterizing him as a "friend of Babylon's sultan", "of Saracen customs", "provided with a harem guarded by eunuchs", like the schismatic emperor of Byzantium, and in sum a "heretic". The “deposition” of the emperor provoked consternation from other European monarchs and, weary of the interference of an overweening pope, none offered any support to Innocent. Louis IX, sympathetic to the emperor, refused Innocent’s requests to enter France and Henry III of England, pushed by English discontent with increased church taxes to finance a papal war with Frederick, rebuffed Innocent’s entreaties to move to Gascony. Even within some of the clergy in France, Germany, England, and Italy itself, unrest with Frederick’s “deposition” and the preaching of a crusade against the emperor grew. Nevertheless, the struggle between pope and emperor had become an all-or-nothing one. Frederick was supposed to have declared, “I have been the anvil long enough… now I shall be the hammer.”

In 1246 Innocent set in motion a plot to kill Frederick and Enzo, with the support of the pope's brother-in-law Orlando de Rossi, another friend of Frederick. The assassination of Frederick would be the signal for a general uprising against imperial rule across Italy. However, while the emperor was staying in Grosseto, the plotters were unmasked by Riccardo Sanseverino, Count of Caserta, after one of their number, Giovanni da Presenzano, betrayed them. The chief conspirators were some of the emperor’s closest friends and officials. Among them was the former Imperial vicar of Tuscany, Pandolfo Fasanella, Jacobo di Morra—son of Frederick’s long-serving minister Henry of Morra, Ruggero de Amicis—a justiciar and ambassador of the emperor, Teobaldo di Francesco—imperial podestà of Parma, and the hitherto loyal Andrew of Cicala, one of Frederick’s chief lieutenants in the Kingdom of Sicily. Frederick dealt ruthlessly with the plot. His lieutenants hunted down the conspirators, destroying their strongholds of Cilento, Sala Consilina, and Altavilla where they had found refuge. The last of the conspirators held out against Frederick’s forces in the castle of Capaccio for most of the summer of 1246 but were forced to surrender for lack of water. Hundreds of the conspirators were captured, including Teobaldo di Francesco. They were blinded, mutilated, and burnt alive or hanged, and their families imprisoned or sold into slavery. The conspiracy was crushed. An attempt to invade the Kingdom of Sicily, under the command of Cardinal Ranieri, was halted at Spello by Marino of Eboli, Imperial vicar of Spoleto. Despite the papal-backed conspiracy against his life, Frederick’s power over the Kingdom of Sicily, central Italy and much of Lombardy remained strong. However, the conspiracy was a personal blow to the emperor, leaving him deeply suspicious of his subordinates and he increasingly relied on his sons. Enzo was already his father’s chief representative in Lombardy while Frederick of Antioch was appointed Imperial vicar of Tuscany.

Innocent also sent a flow of money to Germany to dislodge Frederick's power there. The archbishops of Cologne and Mainz also declared Frederick deposed, and in May 1246 Henry Raspe, Landgrave of Thuringia was chosen as papal-backed anti-king. On 5 August 1246 Henry Raspe, thanks to the Pope's money, managed to defeat an army of Conrad, son of Frederick, near Frankfurt. Frederick strengthened his position in Southern Germany, however, acquiring the Duchy of Austria, whose duke had died without heirs, along with the sizable treasury of the now bereft House of Babenberg. A year later Henry Raspe died, and Innocent selected William II of Holland as the new pro-papal anti-king.

Between February and March 1247 Frederick settled the situation in Italy a diet in Terni, naming his relatives or friends as vicars of the various lands. He married his son Manfred to the daughter of Amedeo di Savoia to secure the Alpine passes to Lyon and compelled the submission of the marquis of Monferrato. A papal army under the command of Ottaviano degli Ubaldini never reached Lombardy, and the Emperor, accompanied by a massive army, held another diet at Turin. Innocent once again asked for protection from the King of France, Louis IX, but the king consistently refused, hoping instead to broker a peace which left Frederick free to support crusading plans in the Levant. However, Louis also warned that he would not accept any direct attack by Frederick against Innocent in Lyon. Despite this, Lyon was technically an imperial city and Frederick stood poised to lead an expedition across the Alps to confront Innocent directly.

Setbacks, recovery, and death

The wooden city of Vittoria is charged at the siege of Parma 1248

The capture of King Enzio a son of Frederick at the Battle of Fossalta 1249

An unexpected event was to change the situation dramatically. In June 1247 the important Lombard city of Parma expelled the Imperial functionaries and sided with the Guelphs. Enzo was not in the city and could do nothing more than ask for help from his father, who came back to lay siege to the rebels, together with his friend Ezzelino III da Romano, tyrant of Verona. The besieged languished as the Emperor waited for them to surrender from starvation. He had a wooden city, which he called "Vittoria", built around the walls.

On 18 February 1248, during one of these absences, the camp was suddenly assaulted and taken, and in the ensuing Battle of Parma the Imperial side was routed. Frederick lost the Imperial treasure and with it his momentum against the rebellious communes in the immediate future. Sensing this, Innocent began plans for a crusade against Sicily. Frederick soon recovered and rebuilt an army, but this defeat encouraged resistance in many cities that could no longer bear the fiscal burden of his regime: parts of the Romagna, Marche and Spoleto were lost. In May 1248, Frederick’s illegitimate son Richard of Chieti defeated a papal army led by Hugo Novellus near Civitanova Marche and recaptured some areas of the Marche and Spoleto. Nevertheless, it was only by strenuous, even unrelenting effort that Frederick was able to stabilize the situation by the close of 1248. Frederick remained confident but after several years of war and conspiracy he was increasingly suspicious and wearied.

In February 1249 Frederick dismissed his advisor and chief minister, the famous jurist and poet Pier delle Vigne, on charges of peculation and embezzlement. Some historians suggest that Pier was planning to betray the Emperor, who, according to Matthew of Paris, cried when he discovered the plot. Pier, blinded and in chains, died in Pisa, possibly by his own hand. Even more shocking for Frederick was the capture of his natural son Enzo of Sardinia by the Bolognese at the Battle of Fossalta, in May 1249. Enzo was held in a palace in Bologna, where he remained captive until his death in 1272. Richard of Chieti was also killed in 1249, possibly in the same battle. Frederick named Manfred as Legate General of Italy to replace the now captive Enzo.

The struggle continued: the Empire lost Como and Modena, but regained Ravenna. From early 1250, the situation progressively favored Frederick II. In the first month of the year, the indomitable Ranieri of Viterbo died, depriving pro-papal leadership in Italy of an implacable foe of Frederick. An army sent to invade the Kingdom of Sicily under the command of Cardinal Pietro Capocci was crushed in the Marche at the Battle of Cingoli and Imperial condottieri again reconquered the Romagna, the Marche and Spoleto. Conrad, King of the Romans, scored several victories in Germany against William of Holland and forced the pro-papal Rhenish archbishops to sign a truce. Innocent IV was increasingly isolated as support for the papal cause dwindled rapidly in Germany, Italy, and across Europe generally. Frederick of Antioch had relatively stabilized Tuscany as imperial vicar and podestà of Florence. Piacenza changed allegiances to Frederick and Oberto Pallavicino, Imperial vicar of Lombardy, recaptured Parma and a swathe of central Lombardy. Ezzelino da Romano held Verona, Vicenza, Padua and the Trevisan March along with most of eastern Lombardy. Only Milan, Brescia, Modena, Mantua, Ferrara, and Bologna held out. Genoa was threatened by Frederick’s allies and Venice’s support for Innocent and the League waned. Even with imperial prospects brightening however, areas of Italy had been ravaged by years of war and even the resources of the wealthy and prosperous Kingdom of Sicily were strained. Frederick’s unified regime in Italy and Sicily was despotic and brutal, imposing harsh taxes and ruthlessly suppressing dissent. Nevertheless, that his administrative system consistently recovered in the face of reversals remains an impressive feat.

Frederick, however, did not take part in any of the campaigns of 1250. He had been ill and likely felt tired, withdrawing to the Kingdom of Sicily where a he remained for much of the year. Suddenly on 13 December 1250, however, after a persistent attack of dysentery, Frederick died in Castel Fiorentino (territory of Torremaggiore), in Apulia. Despite the betrayals, setbacks, and flux of fortune he had faced in his last years, Frederick died peacefully, reportedly wearing the habit of a Cistercian monk. Of his father’s death, Manfred wrote to Conrad in Germany, “The sun of justice has set, the maker of peace has passed away.”

At the time of Frederick’s death, his preeminent position in Europe was challenged but certainly not lost. The political situation remained fluid and the victories of 1250 had put Frederick seemingly in the ascendant once again. Everywhere Innocent IV’s fortunes seemed dire: the papal treasury was depleted, his anti-king William of Holland had been defeated by Conrad in Germany and forced to submit while no other European monarch proved willing to offer much support for fear of Frederick’s ire. In Italy, Frederick’s lieutenants and partisans had recaptured much of the territories lost in the last two years; he was in a strong position and he prepared to march on Lyon in the new year. Despite the economic strains placed on the Regno, support from the Emperor of Nicaea, John III Doukas Vatatzes, enabled Frederick to relatively refill his coffers and resupply his forces. After the failure of Louis IX’s crusade in Egypt, Frederick had skillfully imaged himself as the aggrieved party against the papacy, hindered by Innocent’s machinations from supporting the campaign. Frederick won growing support on the wider diplomatic stage. Only his death halted this momentum. His testament left Conrad the Imperial and Sicilian crowns. Manfred received the principality of Taranto, 100,000 gold ounces, and regency over Sicily and Italy while his half-brother remained in Germany. Henry Charles Otto, Frederick’s son by Isabella of England, received 100,000 gold ounces and the Kingdom of Arles or that of Jerusalem, while the son of Henry VII was entrusted with the Duchy of Austria and the March of Styria. Perhaps aiming to lay stones for a potential peace settlement between Conrad and Innocent—or a final crafty scheme to further demonstrate papal prejudice against him, Frederick's will stipulated that all the lands he had taken from the Church were to be returned to it, all the prisoners freed, and the taxes reduced, provided this did not damage the Empire's prestige. In peacefully passing on his realms to his sons Frederick accomplished perhaps the main goal of any ruler. At his death, the Hohenstaufen empire remained the leading power in Europe and its security seemed assured in the persons of his sons.

Frederick II died one of the greatest, most energetic, imaginative and capable rulers of the entire Middle Ages, bestriding the European stage like a colossus and passing away in the “full glory” of imperial power. Yet, for all the grandeur of his reign, his efforts to bind together Sicily, Italy, and Germany in closer imperial unity ultimately proved futile with the eventual collapse of his dynasty. With an insistent tenacity that so pervaded his pronounced individuality, Frederick had attempted the impossible and achieved the improbable, and his achievements remain astonishing. Upon Conrad's death a mere four years later, the Hohenstaufen dynasty fell from power in Germany, inaugurating the Great Interregnum which lasted until 1273, one year after the last Hohenstaufen, Enzo, had died in his prison. Manfred would succeed to the Sicilian throne in 1258 and enjoyed a good deal of success against the papacy and its Guelph allies until his death at the Battle of Benevento. Conradin, the only son of Conrad IV, made an attempt to reclaim Sicily after Manfred’s death but was defeated and captured at the Battle of Tagliacozzo in 1268 and executed by Charles I of Anjou soon after, ending the Hohenstaufen line. Much of Europe was shocked by the sudden death of Frederick II and a legend developed that Frederick was not truly dead but merely sleeping in the Kyffhäuser Mountains and would one day awaken to reestablish his empire. Over time, this legend largely transferred itself to his grandfather, Frederick I, also known as Barbarossa ("Redbeard").

Frederick’s sarcophagus (made of red porphyry) lies in the cathedral of Palermo beside those of his parents (Henry VI and Constance) as well as his grandfather, the Norman king Roger II of Sicily. He is wearing a funerary alb with a Thuluth-style inscribed cuff. A bust of Frederick sits in the Walhalla temple built by Ludwig I of Bavaria. His sarcophagus was opened in the nineteenth century and various items can be found in the British Museum's collection, including a small piece of funerary crown.

Personality and religion

Frederick II (seated left), the "stupor mundi", receiving homage from the people of the world. Contemporary fresco of the 13th century, Torre San Zeno, Verona

The Court of Emperor Frederick II in Palermo by Arthur von Ramberg

Frederick's contemporaries called him stupor mundi, the “astonishment” or the “wonder of the world”, and immutator mirabilis or the “marvelous transformer [of the world]” for his charismatic personality and his political designs and achievements. This carried with it a tinge of messianism from some of Frederick’s supporters and a sense of the demonic from his opponents. The majority of his contemporaries were indeed astonished, transfixed, and sometimes repelled or terrified by the pronounced unorthodoxy of the Hohenstaufen emperor, his audacious personality and stubbornness, his cruelty and despotism, and his extraordinary ambitions. Even so, the famous English chronicler Matthew of Paris still acclaimed Frederick as the “greatest of the princes of the earth.”

Frederick II’s reputed multifaceted personality remains securely attached to his legacy. He seemed to be insatiably curious about everything: science, naturalism, mathematics, architecture, and poetry, and welcomed many of the most learned figures of his time to his court. He was a conversationalist with an “inexhaustible streak” who “wanted to know everything”. He enjoyed lively intellectual debates and though he could be amiable, he was often passionate and intense. However, his “speciality” was being a calculating, ruthless despot and a “dirigiste technocrat” who aimed to command every aspect of his Italian realms. Frederick’s statecraft, though inventive or perhaps even ingenious, indicates an intolerantly absolutist disposition; a monarch who saw himself as the supreme source of peace, order, and justice, for whom the interests of the State superseded everything. For all his reputed charisma and brilliance, Frederick was at heart a mercurial intellectual who lacked the “common touch” of his grandfather, Frederick Barbarossa, and seemed inclined to more Oriental attractions. Frederick II preferred a select company of intimates with whom he could share his seemingly endless intellectual interests and upon whom he could impress his dominating and protean personality. Even so, he could be temperamental and cruel. Salimbene di Adam, a generally hostile critic of the emperor, wrote that Frederick was alternatively witty, consoling, and delightful, but also cunning, greedy, and malicious, lacking any religious faith.

Maehl argues that Frederick inherited German, Norman, and Sicilian blood, but by training, lifestyle, and temperament he was "most of all Sicilian." "To the end of his life he remained above all a Sicilian grand signore, and his whole imperial policy aimed at expanding the Sicilian kingdom into Italy rather than the German kingdom southward." And according to Cantor, "Frederick had no intention of giving up Naples and Sicily, which were the real strongholds of its power. He was, in fact, uninterested in Germany."

Frederick was a religious sceptic to an extent unusual for his era. His papal enemies used this against him at every turn and accused him of claiming that Moses, Christ, and Mohammed were the three greatest deceivers who ever lived in a long-rumored book called the Treatise of the Three Imposters. The actual existence of this book is highly unlikely and Frederick himself denied all knowledge of it but its supposed sentiment seemed to align with Frederick’s perceived religious skepticism and indifference to personal faith. Innocent IV declared him preambulus Antichristi (predecessor of the Antichrist) on July 17, 1245. As Frederick allegedly did not respect the privilegium potestatis of the Church, he was excommunicated. His rationalistic mind took pleasure in the strictly logical character of Christian dogma. He was not, however, a champion of rationalism, nor had he any sympathy with the mystico-heretical movements of the time; in fact he joined in suppressing them. It was not the Church of the Middle Ages that he antagonized, but its representatives.

For his supposed "Epicureanism" (paganism), Frederick II is listed as a representative member of the sixth region of Dante's Inferno, that of the heretics, who are burned in tombs. It is thought Frederick might have kept a harem in Lucera and perhaps even at his court at Foggia. Frederick was notoriously licentious and fathered at least twelve illegitimate children by several mistresses. Some have even suggested that he was bisexual. Contemporaries were awed and sometimes scornful of Frederick’s “orientalism” and defiance of the conventional bounds of morality.

Literature and science

An image from an old copy of De arte venandi cum avibus

The Cremona elephant as depicted in the Chronica maiora, Part II, Parker Library, MS 16, fol. 151v – On parade during the visit of Frederick's brother-in-law Richard of Cornwall to Cremona in 1241

Frederick had a great thirst for knowledge and learning. Frederick employed Jews from Sicily, who had migrated there from the holy land, at his court to translate Greek and Arabic works. He also introduced paper into a European court.

He played a major role in promoting literature through the Sicilian School of poetry. His Sicilian royal court in Palermo, saw the first use of a literary form of an Italo-Romance language, Sicilian. Through the mix of Arabic, Hebrew, Latin, Greek, and Sicilian language poems and art at the court, Arabic "muwashshahat" or "girdle poems" influenced the birth of the sonnet. The language developed by Giacomo da Lentini and Pier delle Vigne in the Sicilian School of Poetry gathering around Frederick II of Swabia in the first half of the thirteenth century had a decisive influence on Dante Alighieri and then on the development of Italian language itself. The school and its poetry were saluted by Dante and his peers and predate by at least a century the use of the Tuscan idiom as the elite literary language of Italy.

Frederick II is the author of the first treatise on the subject of falconry, De Arte Venandi cum Avibus ("The Art of Hunting with Birds"). In the words of the historian Charles Homer Haskins:

It is a scientific book, approaching the subject from Aristotle but based closely on observation and experiment throughout, Divisivus et Inquisitivus, in the words of the preface; it is at the same time a scholastic book, minute and almost mechanical in its divisions and subdivisions. It is also a rigidly practical book, written by a falconer for falconers and condensing a long experience into systematic form for the use of others.

For this book he drew from sources in the Arabic language. Frederick's pride in his mastery of the art is illustrated by the story that, when he was ordered to become a subject of the Great Khan (Batu) and receive an office at the Khan's court, he remarked that he would make a good falconer, for he understood birds very well. He maintained up to fifty falconers at a time in his court, and in his letters he requested Arctic gyrfalcons from Lübeck and even from Greenland. One of the two existing versions was modified by his son Manfred, also a keen falconer.

David Attenborough in "Natural Curiosities" notes that Frederick fully understood the migration of some birds at a time when all sorts of now improbable theories were common.

Frederick loved exotic animals in general: his menagerie, with which he impressed the cold cities of Northern Italy and Europe, included hounds, giraffes, cheetahs, lynxes, leopards, exotic birds and an elephant.

He was also alleged to have carried out a number of experiments on people. These experiments were recorded by the monk Salimbene di Adam in his Chronicles. Among the experiments were shutting a prisoner up in a cask to see if the soul could be observed escaping through a hole in the cask when the prisoner died; feeding two prisoners, having sent one out to hunt and the other to bed and then having them disemboweled to see which had digested his meal better; imprisoning children and then denying them any human contact to see if they would develop a natural language.

In the language deprivation experiment young infants were raised without human interaction in an attempt to determine if there was a natural language that they might demonstrate once their voices matured. It is claimed he was seeking to discover what language would have been imparted unto Adam and Eve by God. In his Chronicles Salimbene wrote that Frederick bade "foster-mothers and nurses to suckle and bathe and wash the children, but in no ways to prattle or speak with them; for he would have learnt whether they would speak the Hebrew language (which had been the first), or Greek, or Latin, or Arabic, or perchance the tongue of their parents of whom they had been born. But he laboured in vain, for the children could not live without clappings of the hands, and gestures, and gladness of countenance, and blandishments".

Frederick was also interested in the stars, and his court was host to many astrologers and astronomers, including Michael Scot and Guido Bonatti. He often sent letters to the leading scholars of the time (not only in Europe) asking for solutions to questions of science, mathematics and physics.

In 1224 he founded the University of Naples, the world's oldest state university: now called Università Federico II. Frederick chose Naples for its strategic position and its already strong role as a cultural and intellectual center. The university focused on law and rhetoric, meant to train a new generation of jurists and officials to staff Frederick’s burgeoning bureaucracy. Its students and faculty were state sponsored and forbidden from attending other universities outside the kingdom. Perhaps the university’s most famous student and lecturer was the philosopher and theologian Thomas Aquinas.

Appearance

A Damascene chronicler, Sibt ibn al-Jawzi, left a physical description of Frederick based on the testimony of those who had seen the emperor in person in Jerusalem: "The Emperor was covered with red hair, was bald and myopic. Had he been a slave, he would not have fetched 200 dirhams at market." Frederick's eyes were described variously as blue, or "green like those of a serpent".

Law reforms

Castle of Melfi where the Constitutions were redacted

Frederick II’s most profound and revolutionary legal legacy remains the Constitutions of Melfi or Constitutiones Regni Siciliarum (English: Constitutions of the Kingdom of the Sicilies), promulgated in 1231 in the Kingdom of Sicily. The sophistication of the Constitutions, also known as the Liber Augustalis, and his involvement in their formulation sets Frederick apart as perhaps the supreme lawgiver of the Middle Ages. Under the direction of a group of jurists headed by Frederick himself, including Roffredo Epifanio, Pier della Vigna, and archbishops Giacomo Amalfitano of Capua and Andrea Bonello of Barletta, the Constitutions aimed to harmonize decades of Siculo-Norman legal tradition stretching back to Roger II. Almost every aspect in Frederick’s tightly-governed kingdom was regulated, from a rigorously centralized judiciary and bureaucracy, to commerce, coinage, financial policy, legal equality for all citizens, protections for women and prostitutes, and even provisions for the environment and public health. The kingdom was divided into eleven territorial districts called justiciaries governed by justiciars appointed by Frederick.

The purview of the justiciars reached across administrative, judicial, and even religious fields and each was subordinate to a Master Justiciar of the respective region who maintained direct contact with Frederick within a pyramid-like hierarchical structure. The magistrates were elected for a year pending reaffirmation and received a salary from the state. This made them loyal to the king-emperor and his administration, for without it they were nothing. The great officers of the Regno were the ancient ammiratus ammiratorum, the grand protonotary (or logothete), great Chamberlain, great seneschal, great chancellor, great constable, and master justiciar. The last was the head of the Magna Curia, the court of the king (his curia regis) and the final court of appeal. The Magna Curia Rationum, a division of the curia, acted as an auditing department on the great bureaucracy. Frederick also allowed access by parts of civil society to the Sicilian Parliament which now consisted of not only the barons, but the University of Naples, the medical school at Salerno, and landed commoners. It did not debate or even rubber-stamp legislation, which was the king's to make and unmake, but merely received it and promulgated, giving its advice where it could. State monopolies were imposed on silk, iron, and grain while tariffs and import duties on trade within the kingdom were abolished. A new gold coin called an augustalis was introduced and became widely circulated in Italy, admired even today for its splendid proto-Renaissance style and fine quality. Per the Constitutions, Frederick II was lex animata and ruled as an absolute monarch. The Constitutions have been regarded as perhaps the “birth certificate” of the modern continental European state, and as such Frederick’s influence remains enormous.

An augustale of Frederick II from Brindisi, Italy, struck after 1231. Reverse legend: "fridericus".

From 1240, Frederick II was determined to push through far-reaching reforms to establish the Sicilian kingdom and Imperial Italy as unified state bound by a centralized administration. He appointed Enzo as Legate General for the whole of Italy along with several imperial vicars and captains-general to govern the provinces. Frederick placed loyal Sicilian barons as podestàs over the subjected cities of northern and central Italy. The unified administration was taken over directly by the emperor and his highly trained Sicilian officials whose jurisdiction now ranged across all of Italy. Henceforth, the new High Court of Justice would be supreme in both the Kingdom of Sicily and Imperial Italy. A central exchequer was established at Melfi to oversee financial management. Frederick also made efforts towards regulating education, commerce, and even medicine, similar to his earlier reforms in Sicily. For the rest of his reign, there was a continuous movement toward the extension and perfection of this new unified administrative system, with the emperor himself as the driving force. Despite his mighty efforts however, Frederick’s newly unified Italian state ultimately proved ephemeral. Robbed of his remarkable talent for state-building in its formative years, Frederick’s work did not long survive him and Italian unification stalled until the 19th century. Nevertheless, the vicars and captains-general provided the prototype for the great Signori who dominated Italy in later generations, each a petty sovereign in Frederick’s image aspiring to claim for themselves a measure of his prestige and might—some even continued to claim the title of imperial vicar.

In 1241 Frederick introduced the Edict of Salerno (sometimes called the "Constitution of Salerno") which made the first legally fixed separation of the occupations of physician and apothecary. Physicians were forbidden to double as pharmacists and the prices of various medicinal remedies were fixed. This became a model for regulation of the practice of pharmacy throughout Europe.

Despite his efforts in Sicily and Italy, Frederick II was not able to extend his more absolutist legal reforms to Germany. In 1232, Henry (VII) was forced by the German princes to promulgate the Statutum in favorem principum. Frederick, embittered but aiming to promote cohesion in Germany in preparation for his campaigns in northern Italy, pragmatically agreed to Henry’s confirmation of the charter. It was a charter of liberties for the leading German princes at the expense of the lesser nobility and the entirety of the commoners. The princes gained whole power of jurisdiction, and the power to strike their own coins. The emperor lost his right to establish new cities, castles and mints over their territories. For many years, the Statutum was thought in German historiography to have severely weakened central authority in Germany. However, it is now viewed as more a confirmation of political realities which did not necessarily denude royal power or prevent imperial officials from enforcing Frederick’s prerogatives. Rather, the Statutum affirmed a division of labor between the emperor and the princes and laid much groundwork for the development of particularism and, perhaps even federalism in Germany. Even so, from 1232 the vassals of the emperor had a veto over imperial legislative decisions and any new law established by the emperor had to be approved by the princes. These provisions not withstanding, royal power in Germany remained strong under Frederick.

By the 1240s the crown was almost as rich in fiscal resources, towns, castles, enfeoffed retinues, monasteries, ecclesiastical advocacies, manors, tolls, and all other rights, revenues, and jurisdictions as it had ever been at any time since the death of Henry VI. It is unlikely that a particularly “strong ruler” such as Frederick II would have even pragmatically agreed to legislation that was concessionary rather than cooperative, neither would the princes have insisted on such. Frederick II used the political loyalty and practical jurisdictions “granted” to the higher German aristocracy to support his kingly duty of imposing peace, order, and justice upon the German realm. This is shown clearly in the imperial Landfriede issued at Mainz in 1235, which explicitly enjoined the princes as loyal vassals to exercise their own jurisdictions in their own localities. The jurisdictional autarky of the German princes was favoured by the crown itself in the twelfth and thirteenth centuries in the interests of order and local peace. The inevitable result was the territorial particularism of churchmen, lay princes, and interstitial cities. However, Frederick II was a ruler of vast territories and “could not be everywhere at once”. The transference of jurisdiction was a practical solution to secure the further support of the German princes.

Significance and legacy

Main article: Cultural depictions of Frederick II, Holy Roman Emperor § Historiography

See also: Subventio generalis

A 1781 picture showing the mummified corpse of Frederick II in Palermo

Historians rate Frederick II as a highly significant European monarch of the Middle Ages. This reputation was present even among his contemporaries, many of whom viewed him in proto-Napoleonic hues. For centuries, Frederick has retained the enduring fascination of historians. In his influential work The Civilization of the Renaissance in Italy 19th century German historian and philosopher Jacob Burckhardt called Frederick the “first modern man on the throne.” Ernst Kantorowicz's biography, Frederick the Second, original published in 1927, is a very influential work in the historiography of the emperor. Kantorowicz praises Frederick as a genius, who created the "first western bureaucracy", an "intellectual order within the state" that acted like "an effective weapon in his fight with the Church—bound together from its birth by sacred ties in the priestly-Christian spirit of the age, and uplifted to the triumphant cult of the Deity Justitia." For Kantorowicz, Frederick was a trans-European ruler “deeply imbued” with the idea of a renovatio imperii. While Kantorowicz endorsed Burckhardt's thinking that Frederick was the prototypical modern ruler, whose Gewaltstaat (tyrannical state) later became the model of tyrannies for all Renaissance princes, Kantorowicz primarily saw Frederick as the last and greatest Christian emperor who embraced "Medieval World Unity". Coupled with this, Kantorowicz also saw Frederick as a “supremely versatile” man and the “Genius of the Renaissance”—a harbinger by which later figures would be measured against.

For the famous 19th century English historian Edward Augustus Freeman, in genius and accomplishments, Frederick II was “surely the greatest prince who ever wore a crown”, superior to Alexander, Constantine or Charlemagne, who failed to grasp nothing in the “compass of the political or intellectual world of his age”. Freeman even considered Frederick to have been the last true Emperor of the West. Lionel Allshorn wrote in his 1912 biography of the emperor that Frederick surpassed all of his contemporaries and introduced the only enlightened concept of the art of government in the Middle Ages. For Allshorn, Frederick II was the “redoubtable champion of the temporal cause” and who, unlike Emperor Henry IV or even Frederick Barbarossa, never humiliated himself before the papacy and steadfastly maintained his independence. Dr. M. Schipa, in the Cambridge Medieval History, considered Frederick II a “creative spirit” who had “no equal” in the centuries between Charlemagne and Napoleon, forging in Sicily and Italy “the state as a work of art” and laid the “fertile seeds of a new era.” The noted Austrian cultural historian Egon Friedell saw Frederick as the greatest of the ‘four great rulers’ in history, embodying the far-seeing statecraft of Julius Caesar, the intellectuality of Frederick the Great, and the enterprise and “artist’s gaminerie” of Alexander the Great. For Friedell, Frederick’s “free mind” and “universal comprehension” of everything human stemmed from the conviction that no one was right. W. Köhler wrote that Frederick’s “marked individuality” made him the “ablest and most mature mind” of the Hohenstaufen who towered above his contemporaries. For Frederick, knowledge was power, and because of his knowledge, he wielded despotic power. Though the “sinister facts” of his despotism should not be ignored, the greatness of his mind and his energetic will compels admiration.

Modern medievalists generally no longer accept the notion, sponsored by the popes, of Frederick as an anti-Christian. They argue that Frederick understood himself as a Christian monarch in the sense of a Byzantine emperor, thus as God's "viceroy" on earth. Whatever his personal feelings toward religion, certainly submission to the pope did not enter into the matter in the slightest. This was in line with the Hohenstaufen Kaiser-Idee, the ideology claiming the Holy Roman Emperor to be the legitimate successor to the Roman Emperors. As his father Henry VI, Frederick established a famous reputation for his cosmopolitan court, which included figures such as the black treasury custodian Johannes Morus, the mathematician Fibonacci, the scholar Michael Scot, the translator John of Palermo, the physician John of Procida, the Syrian philosopher Theodore of Antioch, and the poet Giacomo da Lentini, that persisted throughout the rest Late Middle Ages and into the Renaissance.

20th century treatments of Frederick vary from the sober (Wolfgang Stürner) to the dramatic (Ernst Kantorowicz). However, all agree on Frederick II's significance as Holy Roman Emperor and as a forerunner, perhaps, for succeeding generations of a conception of the “modern” state emancipated from papal claims of supremacy. Thomas Curtis Van Cleve's 1972 The Emperor Frederick II of Hohenstaufen, Immutator Mundi acknowledges the emperor's genius, as a ruler, lawgiver and scientist, and also as an extraordinary figure. In this way, even leaving aside his cultural influence or intellectual sophistication, Frederick II can perhaps be seen as a pivot point between the Middle Ages and the Renaissance. The modern approach to Frederick II tends to be focused on the continuity between Frederick and his predecessors as Kings of Sicily and Holy Roman Emperors, and the similarities between him and other thirteenth-century monarchs. David Abulafia, in his biography subtitled "A Medieval Emperor", argues that Frederick's reputation as an enlightened figure ahead of his time is undeserved, and that Frederick was mostly a conventionally Christian monarch who sought to rule in a conventional medieval manner. Nevertheless, Frederick II still commands a lasting popular reputation as a polyhedral monarch who transcended his time. Even today, the memory of Frederick II is of a personality of extraordinary breadth and ability: a polymath and polyglot, statesman and lawgiver, poet, scientist and mathematician; a brilliant proto-enlightened despot and cunning politician at the head of a sophisticated state, surrounded by his vibrant court which seemed to presage the Renaissance.

Lansing and English, two British historians, argue that medieval Palermo has been overlooked in favor of Paris and London:

One effect of this approach has been to privilege historical winners, [and] aspects of medieval Europe that became important in later centuries, above all the nation state.... Arguably the liveliest cultural innovation in the 13th century was Mediterranean, centered on Frederick II's polyglot court and administration in Palermo.... Sicily and the Italian South in later centuries suffered a long slide into overtaxed poverty and marginality. Textbook narratives therefore focus not on medieval Palermo, with its Muslim and Jewish bureaucracies and Arabic-speaking monarch, but on the historical winners, Paris and London.

Friedrich Nietzsche, a prominent German philosopher, mentioned Frederick in his book Beyond Good and Evil (Part V, aphorism 200). Nietzsche seems to admire Frederick as an archetypal übermensch who resisted the conventional morals of his time and had the courage to create his own moral code to live by. He compares Frederick to figures like Caesar and Leonardo da Vinci, both of whom he sees as embodying strong individualism and, most importantly, the will to power—which Nietzsche believed to be the very core of human greatness.

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  Stained glass windows from the Strasbourg Cathedral, Bas-Rhin, Alsace, France, dated circa 1210–1270, depicting emperors of the Holy Roman Empire: Philip of Swabia, Henry IV, Henry V, and Frederick II
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  A statue of Frederick II from the Black Tower of Regensburg, c. 1280–1290
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  Flowers at the tomb of Frederick II in the Cathedral of Palermo

Family

Frederick left numerous children, legitimate and illegitimate:

Legitimate issue

The wedding of Frederick II and Isabella of England

First wife: Constance of Aragon (1179 – 23 June 1222). Marriage: 15 August 1209, at Messina, Sicily.

• Henry (VII) (1211 – 12 February 1242).

Second wife: Isabella II of Jerusalem (1212 – 25 April 1228). Marriage: 9 November 1225, at Brindisi, Apulia.

• Margareta (November 1226 – August 1227).
• Conrad IV (25 April 1228 – 21 May 1254).

Third wife: Isabella of England (1214 – 1 December 1241). Marriage: 15 July 1235, at Worms, Germany.

• Jordan (born during the spring of 1236, failed to survive the year); this child was given the baptismal name Jordanus as he was baptized with water brought for that purpose from the Jordan river.
• Agnes (b and d. 1237).
• Henry Charles Otto (18 February 1238 – May 1253), named after Henry III of England, his uncle; appointed Governor of Sicily and promised to become King of Jerusalem after his father died, but he, too, died within three years and was never crowned. Betrothed to many of Pope Innocent IV's nieces, but never married to any.
• Margaret (1 December 1241 – 8 August 1270), married Albert, Landgrave of Thuringia, later Margrave of Meissen.

Mistresses and illegitimate issue

The Codex Manesse showing the poet Konrad von Altstetten with a mistress and a bird of prey; though it is often claimed that it actually depicts Frederick and Bianca

• Unknown name, Sicilian countess. Her exact parentage is unknown, but Thomas Tuscus's Gesta Imperatorum et Pontificum (c. 1280) stated she was a nobili comitissa quo in regno Sicilie erat heres.
  • Frederick of Pettorano (1212/13 – after 1240), who fled to Spain with his wife and children in 1240.
• Adelheid (Adelaide) of Urslingen (c. 1184 – c. 1222). Her relationship with Frederick II took place during the time he stayed in Germany between 1215 and 1220. According to some sources, she was related to the Hohenburg family under the name Alayta of Vohburg (it: Alayta di Marano); but the most accepted theory stated she was the daughter of Conrad of Urslingen, Count of Assisi and Duke of Spoleto.
  • Enzo of Sardinia (1215–1272). The powerful Bentivoglio family of Bologna and Ferrara claimed descent from him.
  • Caterina da Marano (1216/18 – aft. 1272), who married firstly with NN and secondly with Giacomo del Carretto, marquis of Noli and Finale.
• Matilda or Maria, from Antioch.
  • Frederick of Antioch (1221–1256). Although Frederick has been ascribed up to eight children, only two, perhaps three, can be identified from primary documents. His son, Conrad, was alive as late as 1301. His daughter Philippa, born around 1242, married Manfredi Maletta, the grand chamberlain of Manfredi Lancia, in 1258. She was imprisoned by Charles of Anjou and died in prison in 1273. Maria, wife of Barnabò Malaspina, may also have been his daughter.
• An unknown member of the Lancia family:
  • Selvaggia (1221/23 – 1244), married Ezzelino III da Romano.
• Manna, niece of Berardo di Castagna, Archbishop of Palermo:
  • Richard of Chieti (1224/25 – 26 May 1249).
• Anais of Brienne (c. 1205–1236), cousin of Isabella II of Jerusalem:
  • Blanchefleur (1226 – 20 June 1279), Dominican nun in Montargis, France.
• Richina of Wolfsöden (c. 1205 – 1236):
  • Margaret of Swabia (1230–1298), married Thomas of Aquino, count of Acerra.
• Unknown mistress:
  • Gerhard of Koskele (died after 1255), married Magdalena, daughter of Caupo of Turaida.

Frederick had a relationship with Bianca Lancia (c. 1200/10 – 1230/46), possibly starting around 1225. One source states that it lasted 20 years. They had three children:

• Constance (Anna) (1230 – April 1307), married John III Ducas Vatatzes.
• Manfred (1232 – killed in battle, Benevento, 26 February 1266), first Regent, later King of Sicily.
• Violante (1233–1264), married Riccardo Sanseverino, count of Caserta.

Matthew of Paris relates the story of a marriage confirmatio matrimonii in articulo mortis (on her deathbed) between them when Bianca was dying, but this marriage was never recognized by the Church. Nevertheless, Bianca's children were apparently regarded by Frederick as legitimate, legitimatio per matrimonium subsequens, evidenced by his daughter Constance's marriage to the Nicaean Emperor, and his own will, in which he appointed Manfred as Prince of Taranto and Regent of Sicily.

Gallery

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  The Castello Svevo at Trani built by Frederick II from 1233–1249
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  Castel del Monte near Andria built by King Frederick II from 1240-1250
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  Arms of the House of Hohenstaufen
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  Arms of the House of Hohenstaufen as Holy Roman Emperor
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  Attributed Coat of Arms of Frederick II, Holy Roman Emperor (or, double-headed eagle sable)
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  Coat of Arms of the Kingdom of Sicily (House of Hohenstaufen)

Ancestry

Ancestors of Frederick II, Holy Roman Emperor

8. Frederick II, Duke of Swabia 4. Frederick I, Holy Roman Emperor 9. Judith of Bavaria 2. Henry VI, Holy Roman Emperor 10. Renaud III, Count of Burgundy 5. Beatrice I, Countess of Burgundy 11. Agatha of Lorraine 1. Frederick II, Holy Roman Emperor 12. Roger I, Count of Sicily 6. Roger II of Sicily 13. Adelaide del Vasto 3. Constance I of Sicily 14. Ithier, Count of Rethel 7. Beatrice of Rethel 15. Beatrice of Namur

See also

• Dukes of Swabia family tree
• Family tree of the German monarchs
• Frederick the Second, Kantorowicz's biography of Frederick

Bibliography

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• Alio, Jacqueline (2017). The Ferraris Chronicle: Popes, Emperors, and Deeds in Apulia 1096–1228. Trinacria. ISBN 978-1-943-63916-8.
• Barraclough, Geoffrey (1984). The Origins of Modern Germany. Norton. ISBN 0-393-30153-2.
• Busk, William (1856). Mediæval popes, emperors, kings, and crusaders; or, Germany, Italy, and Palestine from A.D. 1125 to A.D. 1268, Volume III. London: Hookham & Sons. Retrieved 4 March 2020. contents.
• Busk, William (1856). Mediæval popes, emperors, kings, and crusaders; or, Germany, Italy, and Palestine from A.D. 1125 to A.D. 1268, Volume IV. London: Hookham & Sons. Retrieved 5 March 2020.
• Cassady, Richard F. (2011). The Emperor and the Saint: Frederick II of Hohenstaufen, Francis of Assisi, and Journeys to Medieval Places. DeKalb: Northern Illinois University Press.
• Cavendish, Richard (December 2000). "Death of the Emperor Frederick II". History Today. 50 (12).
• Davis, R. H. C. (1988). A History of Medieval Europe. Longman. ISBN 0-582-01404-2.
• Fournier, Paul (1885). Le royaume d'Arles et de Vienne sous le règne de Frédéric II (1214–1250). Grenoble: G. Dupont.
• Houben, Hubert (2002). Roger II of Sicily: A Ruler Between East and West. Cambridge University Press.
• Jackson, Peter (2005). The Mongols and the West, 1221–1410. Routledge.
• Jedin, Hubert; Dolan, John Patrick, eds. (1980). History of the Church: From the High Middle Ages to the eve of the Reformation, Volume IV. London: Burns & Oates Publishers. ISBN 9780860120865. Retrieved 6 March 2020.
• Jones, Chris (2007). Eclipse of Empire? Perceptions of the Western Empire and its Rulers in Late-Medieval France. Brepols.
• Kamp, N (1975). "Capocci, Raniero (Raynerius de Viterbio, Rainerius, Ranerius, Reinerius)". Dizionario Biografico degli Italiani (in Italian). Vol. 18. Treccani. Retrieved 20 June 2013.
• Kamp, N (1995). "Federico II di Svevia, imperatore, re di Sicilia e di Gerusalemme, re dei Romani". Dizionario Biografico degli Italiani (in Italian). Vol. 45. Treccani. Retrieved 26 May 2019.
• Kantorowicz, Ernst (1931). Frederick the Second, 1194–1250. Translated by E. O. Lorimer. Frederick Ungar.
• Kantorowicz, Ernst (1937). Frederick the Second, 1194–1250. New York: Frederick Ungar.
• Kohn, George Childs (1999). Dictionary of Wars (Revised ed.). New York: Facts On File, Inc. ISBN 0-8160-3928-3.
• Loud, G. A. (2016) [2011]. "The Papal 'Crusade' against Frederick II in 1228–1230". In Michel Balard (ed.). La Papauté et les croisades / The Papacy and the Crusades. Routledge. pp. 91–103.
• Maalouf, Amin (1989). The Crusades Through Arab Eyes. Schocken. ISBN 0-8052-0898-4.
• Mendola, Louis (2016). Frederick, Conrad and Manfred of Hohenstaufen, Kings of Sicily: The Chronicle of Nicholas of Jamsilla. Trinacria. ISBN 978-1-943-63906-9.
• Masson, Georgina (1957). Frederick II of Hohenstaufen. Martin Secker & Warburg. ISBN 88-452-9107-3.
• Powell, James M. (April 2007). "Church and Crusade: Frederick II and Louis IX". Catholic Historical Review. 93 (2): 251–264. doi:10.1353/cat.2007.0201. S2CID 154964516.
• Pybus, H. J. (1930). "The Emperor Frederick II and the Sicilian Church". Cambridge Historical Journal. 3 (2): 134–163. doi:10.1017/s1474691300002444.
• Saunders, J. J. (1971). The History of the Mongol Conquests. Routledge & Kegan Paul. ISBN 9780710070739.
• Scales, Len (2012). The Shaping of German Identity: Authority and Crisis, 1245–1414. Cambridge University Press.
• Smith, Thomas W. "Between two kings: Pope Honorius III and the seizure of the Kingdom of Jerusalem by Frederick II in 1225." Journal of Medieval History 41, 1 (2015): 41–59.
• Sodders, Daniel R. (1996). Conrad the Fourth as German King, 1237–1250 (PhD dissertation). University of Kansas.
• Van Cleve, T. C. (1972). The Emperor Frederick II of Hohenstaufen: Immuntator Mundi. Oxford. ISBN 0-198-22513-X.
• Vercamer, Grischa (2021). "The Mongol Invasion in the Year 1241—Reactions among European Rulers and Consequences for East Central European Principalities". Zeitschrift für Ostmitteleuropa-Forschung. 70 (2): 227–262. doi:10.25627/202170210926.
• Whalen, Brett Edward (2019). The Two Powers: The Papacy, the Empire, and the Struggle for Sovereignty in the Thirteenth Century. University of Pennsylvania Press.
• Wood, Casey A.; Fyfe, F. Marjorie, eds. (2004) [c. 1250]. The Art of Falconry: Being the De arte venandi cum avibus of Frederick II of Hohenstaufen. Stanford: Stanford University Press. ISBN 978-0-8047-0374-1. OCLC 474664651.

External links

• Texts on Wikisource:
  • "Frederick II. King of Sicily from 1197, and Holy Roman Emperor from 1215 to 1250". New International Encyclopedia. 1905.
  • "Frederick II., Roman Emperor". Encyclopædia Britannica (11th ed.). 1911.
  • "Frederick II". Catholic Encyclopedia. 1913.
  • "Frederick II, emperor of the Holy Roman Empire". Encyclopedia Americana. 1920.
  • "Frederick II". Collier's New Encyclopedia. 1921.

• Frederick II – Encyclopædia Britannica
• Psalter of Frederick II from around 1235–1237
• Literature by and about Friedrich II. in the German National Library catalogue
• Works by and about Frederick II, Holy Roman Emperor in the Deutsche Digitale Bibliothek (German Digital Library)
• "Fridericus II Imperator". Repertorium "Historical Sources of the German Middle Ages" (Geschichtsquellen des deutschen Mittelalters).
• Stupor mundi Italian website
• Deed by Frederick II for the branch of the Teutonic Order in Nuremberg, 30 January 1215, "digitalised image". Photograph Archive of Old Original Documents (Lichtbildarchiv älterer Originalurkunden). University of Marburg..