Fredrick II was King of Sicily and Emperor of the Holy Roman Empire. He was born on December 26, 1194 in Jesi, Italy. His father, Henry VI Hohenstaufen, Emperor of the Holy Roman Empire, died when Fredrick was only three. The title of Emperor is elective and not hereditary, so Fredrick did not immediately succeed his father upon his death. He inherited the Kingdom of Sicily  when he was four. His mother died that same year, and Pope Innocent III assumed regency of the Sicilian throne until Fredrick came of age. In the wake of a series of political upheavals in Sicily, Fredrick was left to his own devices. He educated himself, growing up in the streets of Palermo, helped by poor people in the suburbs.Pope Innocent III eventually became his tutor again, taking the young heir under his protection. When he was 14, Fredrick became King of Sicily. In 1220 [November 22, 1220] he was named Emperor of the Holy Roman Empire, ruler of Northern Italy’s German territories. The new Pope, Honorius III, supported his appointment, but only under certain conditions. Fredrick had to promise not to unite the Empire and the Kingdom of Sicily, which would surround the Papacy and threaten its control of Central Italy. Also, the new Emperor had to swear to lead a Crusade against the Muslims who had occupied Jerusalem, the Christians’ sacred city.
Fredrick delayed his departure, preferring to work on reforming Sicilian institutions and establishing the University of Naples . He turned his court into a major cultural hub, a meeting point for European and Arab traditions. In 1227, under threat of excommunication, Fredrick finally embarked on the crusade he had promised to lead. He sailed for Jerusalem, but an epidemic forced his army to return to Italy. The new Pope Gregory IX did not believe the story and excommunicated Fredrick. A year later the Emperor organized another crusade. He reached Jerusalem and managed to conquer the city without a fight, using only skilful diplomacy. Fredrick was named King of Jerusalem,  and the excommunication was later absolved. Back in Italy, he had to face the Lombard League, an alliance of Northern Italian cities that had already fought against his grandfather Fredrick I. The League was defeated in 1237. Fearing Fredrick intended to unite the Empire and the Kingdom of Sicily, in 1239 Pope Gregory IX excommunicated him for the second time. In 1245 the new Pope Innocent IV confirmed the excommunication. He did so with the support of German princes who already had a new candidate for the title of Emperor. Fredrick died suddenly on December 13, 1250 in Fiorentino di Puglia. He was 55. A skilful politician and a man of great culture, Fredrick II was nicknamed stupor mundi, wonder of the world.