Frederick II, Holy Roman Emperor

Frederick II (26 December 1194 – 13 December 1250), was one of the most powerful Holy Roman Emperors of the Middle Ages and head of the House of Hohenstaufen. His political and cultural ambitions, based in Sicily and stretching through Italy to Germany, and even to Jerusalem, were enormous; however, his enemies, especially the popes, prevailed, and his dynasty collapsed soon after his death. Historians have searched for superlatives to describe him, as in the case of Professor Donald Detwiler, who wrote:

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 of Hauteville, 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.

He was frequently at war with the Papacy, hemmed in between Frederick's lands in northern Italy and his Kingdom of Sicily (the Regno) to the south, and thus he was excommunicated four times and often vilified in pro-papal chronicles of the time and since. Pope Gregory IX went so far as to call him the Antichrist.

Speaking six languages (Latin, Sicilian, German, French, Greek and Arabic ), Frederick was an avid patron of science and the arts. He played a major role in promoting literature through the Sicilian School of poetry. His Sicilian royal court in Palermo, from around 1220 to his death, 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. 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.

After his death, his line quickly died out and the House of Hohenstaufen came to an end.

Early years
Born in Iesi, near Ancona, Italy, Frederick was the son of the emperor Henry VI. He was known as the puer Apuliae (son of Apulia). Some chronicles say that his mother, the forty-year-old Constance, gave birth to him in a public square in order to forestall any doubt about his origin. Frederick was baptised in Assisi.

In 1196 at Frankfurt am Main the infant Frederick was elected King of the Germans. His rights in Germany were disputed by Henry's brother Philip of Swabia and Otto of Brunswick. At the death of his father in 1197, Frederick was in Italy travelling 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 as King on 17 May 1198, now Frederick I of Sicily, at only two years of age.

Constance of Sicily was in her own right queen of Sicily, and she established herself as regent. In Frederick's name she dissolved Sicily's ties to Germany and the Empire that had been created by her marriage, sending home his German counsellors and renouncing his claims to the German throne and empire.

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. However, Markward of Annweiler, with the support of Henry's brother, Philip of Swabia, reclaimed the regency for himself and invaded the Kingdom of Naples. 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. His first task was to reassert his power over Sicily and southern Italy, where local barons and adventurers had usurped most of the authority.

Emperor
Otto of Brunswick had been crowned Holy Roman Emperor by Pope Innocent III in 1209. In southern Italy, Otto became the champion of those noblemen and barons who feared Frederick's increasingly strong moves against them, exemplified by the firing 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 as king on 9 December 1212 in Mainz. Frederick's authority in Germany remained tenuous, however, and he was recognized only in southern Germany; in northern Germany, the center of Guelph power, Otto continued to hold the reins of royal and imperial power despite his excommunication. But 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 on 23 July 1215 by one of the three German archbishops. 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 Philip II of France and Eudes 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. After his coronation in 1220, Frederick remained either in the Kingdom of Sicily or on Crusade until 1236, 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.

The Fifth Crusade and early policies in northern Italy
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 not after 1227, Frederick summoned an imperial Diet at Cremona, the main pro-imperial city in Lombardy: the main arguments would be the struggle against heresy, the organization of the crusade and, above all, the restoration of the imperial power in northern Italy, which had been long usurped by the numerous communes there. These 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, and the situation was set only through a compromise found 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.

The Sixth Crusade
Problems of stability within the empire delayed Frederick's departure on crusade. It was not until 1225, when, by proxy, Frederick had married Yolande 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:

Frederick eventually sailed again from Brindisi in June 1228. The pope regarded that action as a provocation, since, as an excommunicate, Frederick was technically not capable of conducting a Crusade, and excommunicated the emperor a second time. Frederick reached Acre in September. Since all the local authorities denied him any help and most of the military orders denied him any help, and being the crusading army a meagre 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 Yolande, 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.

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 at the Treaty of San Germano, 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".

The war against the Pope and Henry's revolt
During Frederick's stay in the Holy Land, his regent, Rainald of Spoleto, had attacked the Marche 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 Apulia. Frederick arrived at Brindisi in June 1229. He quickly recovered the lost territories and trialled the rebel barons, but avoided crossing the boundaries with the Papal States. The war was solved by the Treaty of San Germano in the summer of 1230; 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), as an attempt to solve the political and administrative problems of the country, which had dramatically been shown by the recent war.

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 ("Statutes 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 anyway compelled to confirm the Statutum at Cividale soon afterwards.

The situation for Frederick was problematic also 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, having no army with him: as soon as July, he was however able to force his son to renounce to the crown and all his lands, at Worms, and then imprisoned him.

In Germany the Hohenstaufen and the Guelphs reconciled in the same year. Otto the Child, the grandson of Henry the Lion, deposed as Duke of Bavaria and Saxony in 1180, conveyed 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 were left without title and rank after 1180.

War in Lombardy
With peace north of the Alps, Frederick obtained by the German princes an army 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 quench 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. Frederick celebrated it 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. He rejected any suit for peace, even from Milan which had sent a great sum of money. This demand of total surrender spurred further resistance from Milan, Brescia, Bologna and Piacenza, and in October 1238 he was forced to raise the siege of Brescia, in the course of which his enemies had tried unsuccessfully to capture him.

Frederick received the news of his excommunication by Gregory IX in the first months of 1239 while his court was in Padua. The emperor responded by expelling the Franciscans and the Dominicans from Lombardy, and electing his son Enzo as Imperial vicar for Northern Italy. Enzo soon annexed the Romagna, Marche and the Duchy of Spoleto, nominally part of the Papal States. The father announced he was to destroy the Republic of Venice, which had sent some ships against Sicily. In December of that year Frederick marched over Tuscany, entered triumphantly into Foligno and then in Viterbo, whence he aimed to finally conquer Rome, in order to restore the ancient splendours of the Empire. The siege, however, was ineffective, and Frederick returned to Southern Italy, sacking Benevento (a papal possession). Peace negotiations came to nothing.

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 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.

The Pope called a council, but Ghibelline Pisa thwarted it, capturing cardinals and prelates on a ship sailing from Genoa to Rome. Frederick thought that this time the way into Rome was opened, and he again directed his forces against the Pope, leaving behind him a ruined and burning Umbria. Frederick destroyed Grottaferrata preparing to invade Rome. Then, on 22 August 1241, Gregory died. Frederick, showing that his war was not directed against the Church of Rome but against the Pope, drew back his troops and freed two cardinals from the jail of Capua. Nothing changed, however, in the relationship between Papacy and Empire, as Roman troops assaulted the Imperial garrison in Tivoli and the Emperor soon reached Rome. This back-and-forth situation was repeated again in 1242 and 1243.

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, and besieged the city. Innocent convinced the rebels to sign a peace but, after Frederick withdrew his garrison, Ranieri nonetheless had them slaughtered on 13 November. Frederick was enraged. The new Pope was a master diplomat, and Frederick signed a peace treaty, which was soon broken. Innocent showed his true Guelph face, and, together with most of the Cardinals, fled via Genoese galleys to Liguria, arriving on 7 July. His aim was to reach Lyon, where a new council was being held since 24 June 1245. Despite initially it seeming that the council could end with a compromise, the intervention of Ranieri, who had a series of insulting 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, Innocent IV declared Frederick to be deposed as emperor, characterising 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 Pope backed Heinrich Raspe, landgrave of Thuringia as his rival for the imperial crown and set in motion a plot to kill Frederick and Enzo, with the support of his (the pope's) brother-in-law Orlando de Rossi, another friend of Frederick's.



The plotters, however, were unmasked by the count of Caserta. The city of Altavilla, where they had found shelter, was razed, and the guilty were blinded, mutilated and burnt alive or hanged. An attempt to invade the Kingdom of Sicily, under the command of Ranieri, was halted at Spello by Marino of Eboli, Imperial vicar of Spoleto.

Innocent also sent a flow of money to Germany to cut off Frederick's power at its source. The archbishops of Cologne and Mainz also declared Frederick deposed, and in May 1246 a new king was chosen in the person of Heinrich Raspe. On 5 August 1246 Heinrich, thanks to the Pope's money, managed to defeat an army of Conrad, son of Frederick, near Frankfurt. But Frederick strengthened his position in Southern Germany, acquiring the Duchy of Austria, whose duke had died without heirs, and one year later Heinrich died as well. The new anti-king was William II, Count of Holland.

Between February and March 1247 Frederick settled the situation in Italy by means of the diet of Terni, naming his relatives or friends as vicars of the various lands. He married his son Manfred to the daughter of Amedeo di Savoia and secured the submission of the marquis of Monferrato. On his part, Innocent asked protection from the King of France, Louis IX; but the king was a friend of the Emperor and believed in his desire for peace. A papal army under the command of Ottaviano degli Ubaldini never reached Lombardy, and the Emperor, accompanied by a massive army, held the next diet in Turin.



The Battle of Parma and the End
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, where he kept his treasure and the harem and menagerie, and from where he could attend his favourite hunting expeditions.

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 any hope of maintaining the impetus of his struggle against the rebellious communes and against the pope, who 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: Romagna, Marche and Spoleto were lost.

In February 1249 Frederick fired his advisor and prime 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 suicide. Even more shocking for Frederick was the capture of his son Enzo of Sardinia by the Bolognese at the Battle of Fossalta, in May of the same year. Only twenty-three at the time, he was held in a palace in Bologna, where he remained captive until his death in 1272.

Frederick lost another son, Richard of Chieti. The struggle continued: the Empire lost Como and Modena, but regained Ravenna. 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 in 1250. In the first month of that year the indomitable Ranieri of Viterbo died and the Imperial condottieri again reconquered Romagna, Marche and Spoleto; and Conrad, King of the Romans scored several victories in Germany against William of Holland.



Frederick did not take part in of any of these campaigns. He had been ill and probably felt himself tired. Despite the betrayals and the setbacks he had faced in his last years, Frederick died peacefully, wearing the habit of a Cistercian monk, on 13 December 1250 in Castel Fiorentino (territory of Torremaggiore), in Puglia, after an attack of dysentery.

At the time of his death, his preeminent position in Europe was challenged but not lost: his testament left his legitimate son Conrad IV the Imperial and Sicilian crowns. Manfred received the principate of Taranto and the government of the Kingdom, Henry the Kingdom of Arles or that of Jerusalem, while the son of Henry VII was entrusted with the Duchy of Austria and the Marquisate of Styria. 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.

However, upon Conrad's death a mere four years later, the Hohenstaufen dynasty fell from power and the Great Interregnum began, lasting until 1273, one year after the last Hohenstaufen, Enzo, had died in his prison. During this time, 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").

His 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. A bust of Frederick sits in the Walhalla temple built by Ludwig I of Bavaria.

Personality
His contemporaries called Frederick stupor mundi, the "wonder" – or, more precisely, the "astonishment" – "of the world"; the majority of his contemporaries were indeed astonished – and sometimes repelled – by the pronounced unorthodoxy of the Hohenstaufen emperor and his temperamental stubbornness.

Frederick II inherited German, Norman, and Sicilian blood, but by training, lifestyle, and temperament he was "most of all Sicilian." Maehl concludes that "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." Cantor concludes, "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 II was a religious skeptic. Despite the accusations of blasphemy and paganism, and the presence of Pagan and oriental elements in his imperial conceptions, Frederick remained substantially linked to traditional Christianism, as shown by his early contacts with both the Franciscans and the Cistercians (in 1215 he was admitted in that order's praying community), as well as with St. Elizabeth. In spite of this, Frederick's religious skepticism was unusual for the era in which he lived, and to his contemporaries, highly shocking and scandalous, and his papal enemies used it against him at every turn; he was subsequently defined preambulus Antichrist by the Pope Gregory IX, and, as Frederick allegedly did not respect the privilegium potestatis of the Church, he became excommunicated.

In Palermo, where the three-year-old boy was brought after his mother's death, he was said to have grown up like a street youth. He was highly precocious. The only benefit from Innocent III's guardianship was that at fourteen years of age he married a twenty-five-year-old widow named Constance, the daughter of the king of Aragon. Both seem to have been happy with the arrangement, and Constance soon bore a son, Henry.

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.

Rather than exterminate the Arab-speaking population of Western Sicily, he deported them at Lucera. Not least, he enlisted them in his Christian army and even into his personal bodyguards. As Muslim soldiers, they had the advantage of immunity from papal excommunication. For these reasons, as well as his supposed Epicureanism, Frederick II is listed as a representative member of the sixth region of Dante's Inferno, The Heretics who are burned in tombs.

A further example of how much Frederick differed from his contemporaries was the conduct of his Crusade in the Holy Land. Outside Jerusalem, with the power to take it, he parlayed five months with the Ayyubid Sultan of Egypt al-Kamil about the surrender of the city. The Sultan summoned him into Jerusalem and entertained him in the most lavish fashion. When the muezzin, out of consideration for Frederick, failed to make the morning call to prayer, the emperor declared: "I stayed overnight in Jerusalem, in order to overhear the prayer call of the Muslims and their worthy God". The Saracens had a good opinion of him, so it was no surprise that after five months Jerusalem was handed over to him, taking advantage of the war difficulties of al-Kamil. The fact that this was regarded in the Arab as in the Christian world as high treason did not matter to him. When certain members of the Knights Templar wrote al-Kamil a letter and offered to destroy Frederick if he lent them aid, al-Kamil handed the letter over to Frederick. As the Patriarch of Jerusalem refused to crown him king, he set the crown on his own head.

Science
Besides his great tolerance (which, however, did not apply to Christian heretics), Frederick had an unlimited thirst for knowledge and learning. Frederick employed Jews from Sicily, who had immigrated there from the holy land, at his court to translate Greek and Arabic works.

To the dislike of some of his contemporaries, Frederick did not believe things that could not be explained by reason. He forbade trials by ordeal in the firm conviction that in a duel the stronger would always win, whether or not he was guilty. Many of his laws continue to influence modern attitudes, such as his prohibition on physicians acting as their own pharmacists. This was a blow to the charlatanism under which physicians diagnosed dubious maladies in order to sell useless, even dangerous "cures".

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:

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.

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 (who despised Frederick) in his Chronicles. Amongst the experiments included shutting a prisoner up in a cask to see if the soul could be observed escaping though a hole in the cask when the prisoner died; feeding two prisoners, sending one out to hunt and the other to bed and then having them disemboweled to see which had digested their meal better; imprisoning children without any 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, it remained the sole atheneum of Southern Italy for centuries.

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
His 1241 Edict of Salerno (sometimes called "Constitution of Salerno") 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.

He was not able to extend his legal reforms beyond Sicily to the Empire. In 1232, he was forced by the German princes to promulgate the Statutum in favorem principum ("statute in favor of princes"). It was a charter of liberties for the leading German princes at the expense of the lesser nobility and 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. The Statutum severely weakened central authority in Germany. From 1232 the vassals of the emperor had a veto over imperial legislative decisions. Every new law established by the emperor had to be approved by the princes.

Evaluation
Historians rate Frederick II as a highly significant European monarch of the Middle Ages. This reputation was present even in Frederick's era. Many modern medievalists reject 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. 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.

Twentieth-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. In the judgment of British historian Geoffrey Barraclough, Frederick's extensive concessions to German princes—which he made in the hopes of securing his base for his Italian projects—undid the political power of his predecessors and postponed German unity for centuries.

Family
Frederick left several children, legitimate and illegitimate:

Legitimate issue

 * First wife: Constance of Aragon (b. 1179 – d. 23 June 1222). Marriage:  15 August 1209, at Messina, Sicily.
 * Henry (VII) (1211 – 12 February 1242).
 * Second wife: Yolande 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 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.
 * Frederick (1239/1240 – died young)
 * Margaret (1 December 1241 – 8 August 1270), married Albert, Landgrave of Thuringia, later Margrave of Meissen.

Frederick had a relationship with Bianca Lancia (ca. 1200/10-1230/46), possibly starting around 1225. One source states that it lasted 20 years. She bore him 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.
 * Violente (1233–1264), married Riccardo Sanseverino, Conte di Caserta.

Matthew of Paris relates the story of a marriage 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, evidenced by his daughter Constance's marriage to the Nicaen Emperor, and his own will, in which he appointed Manfred as Prince of Taranto and Regent of Sicily.

Mistresses and illegitimate issue

 * Unknown name, Sicilian Countess. According to Medlands, she was the first known mistress of Frederick II, by this time King of Sicily. Her exact parentage is unknown, but the Thomas Tusci Gesta Imperatorum et Pontificum stated she was a nobili comitissa quo in regno Sicilie erat heres.
 * Frederick of Pettorana, who fled to Spain with his wife and children in 1240, but both his children died there at the age of two and one.
 * 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).
 * Unknown name, from the family of the Dukes of Spoleto. This relationship is only exposed in Medlands (see above for the entry). Other sources (included Medlands) also stated Catarina was a full sister of Enzo and, in consequence, also daughter of Adelaide of Urslingen.
 * Caterina da Marano (1216/18 – 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).
 * Manna, sister of the Archbishop of Messina.
 * Richard of Chieti (1225 – 26 May 1249).
 * Richina (Ruthina) of Beilstein-Wolfsöden (c. 1205–1236). According to Medlands (who take the information from Europäische Stammtafeln), she was the wife of Count Gottfried of Löwenstein and daughter of some Count Berthold of Beilstein by his wife Adelaide of Bonfeld.
 * Margaret of Swabia (1230–1298), married Thomas of Aquino, count of Acerra.
 * Unknown mistress or mistresses:
 * Selvaggia (1223–1244), married Ezzelino III da Romano
 * Blanchefleur (1226–1279), Dominican nun in Montargis, France.
 * Gerhard (died after 1255).