He was known by the appellation Stupor mundi ('Wonder of the World'), enjoying a reputation as a brilliant Renaissance man avant la lettre and polymath even today: a visionary statesman, an inspired naturalist, scholar, mathematician, architect, poet and composer.

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.

All privileges accorded to anyone whatsoever since the end of William II's reign were ordered to submit for confirmation to the Royal Chancery before Easter 1221 for the mainland provinces and before Whitsun of the same year for the island of Sicily.

[35] Frederick also reestablished the Sicilian navy with provisions based on older Norman laws whereby certain fief holders, including cities and towns of the realm, were bound to furnish timbers or money for shipbuilding and provide for the maintenance of the fleet.

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.

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.

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.

[52] 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.

[64] While he called them traitorous pagans, Frederick expressed 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.

[68] 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.

[83] 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.

Basing himself in Piedmont in June, Frederick hosted many nobles of northern Italy and ambassadors from foreign kings in his court, and neither his deposition nor his defeat at Parma, it seems, had diminished his fame or preeminence.

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 still European monarch proved willing to offer much support for fear of Frederick's ire.

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.

[54] 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.

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.

[96][failed verification] 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.

Because of the "isolated splendour" of his position as emperor and the innate suspicion implanted in him by his early years, instead of the more "normal pursuits" of men of his age, Frederick found respite from the cares of state in the study of science and mathematics, in philosophy and dialectic, in the violent exercise of the chase, and in an "unrestrained abandonment" to sensual pleasures.

How long will this deception last?”[112] The question of Frederick’s personal attitude to religion, whether he was a conventional Christian or a crafty manipulator who was privately more deistic, perhaps even atheistic, remains a persistent topic of debate.

[134] Under the direction of a group of jurists headed by Frederick himself, including Roffredo Epifanio [it], Pier della Vigna, and archbishops Giacomo Amalfitano of Capua and Andrea Bonello of Barletta, the Constitutions harmonized decades of Siculo-Norman legal tradition stretching back to Roger II.

Almost every aspect of 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.

[136] Frederick was the first European monarch to summon the Third Estate and allow civil society access 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.

[147] 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.

Other monarchs, such as Louis IX of France and Henry III of England, tended to accept imperial supremacy, bound up in Frederick's personality and prestige as the preeminent sovereign in Christendom among a community of equal nations.

Rather, it was the specific crises which arose in the reigns of his successors,[92] Conrad and Manfred, and the inherently monumental parameters of the task—itself, perhaps, too much for the lifespan of any single individual, even a monarch of such a forceful personality and manifold genius as Frederick II.

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."

[156] For the famous 19th-century English historian Edward Augustus Freeman, in sheer genius and ability, 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".

[158] 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 laying the "fertile seeds of a new era.

Even today, the general memory of Frederick is of a personality of astonishing breadth and ability: a polymath and polyglot, statesman and lawgiver, poet, mathematician, and naturalist; a brilliant proto-enlightened despot and consummate politician at the head of a sophisticated state, surrounded by his vibrant court which seemed to presage the Renaissance.

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.