When Frederick began his reign, Sicily was in debt and the King was forced to impose high taxes. He introduced laws to promote justice and reduce corruption, but imposed them forcibly, autocratically, and sometimes ruthlessly. While he loved Sicily above his other possessions he seldom remained there, instead leaving his wife, Constance of Aragon, as regent. This caused his subjects in Sicily to question his loyalty to their interests. Finally, he drafted men from Sicily, often for wars in other parts of Frederick's domain. All of these things resulted in Frederick's unpopularity among his Sicilian subjects, although Sicily became prosperous under his rule, and his interest in scholarship and the arts made Frederick's court a major cultural and scientific center of the time.
Frederick's second wife, Yolanda of Brienne, was heiress to the Kingdom of Jerusalem. After his marriage, Frederick undertook a crusade with the primary goal of increasing his influence in the Middle East. Through a treaty with the Sultan of Egypt, he succeeded in taking Palestine without bloodshed, and in 1229 crowned himself King of Jerusalem. His autocratic style quickly made him unpopular in his new kingdom, as in Sicily.
Frederick's relations with the Church began peacefully enough, with his former guardian Innocent III gaining him the throne of the Germans and Innocent's successor Honorius crowning him Holy Roman Emperor in 1220. However, Frederick soon began making aggressive moves against the Lombard towns of Italy, an apparent prelude to an attack on the Papal States. Pope Gregory IX excommunicated Frederick, using as an excuse his procrastination in fulfilling a vow to go on crusade (this was prior to the crusade that made him King of Jerusalem). Pope Gregory further declared a holy war against Frederick. The war between Frederick and Gregory, and later Innocent IV, spread throughout Italy, into Germany, and in time to all of Europe. The Papacy had little in the way of its own army, but was able to call upon supporters from throughout Christendom to battle the anti-christ Frederick. Frederick had Germany, Sicily, and later Jerusalem, as well as supporters in Italy and other parts of Europe, but little loyalty among his subjects. As a result, rival parties of the Pope and the Emperor, the Guelfs and Ghibellines, battled throughout Europe until Frederick's death and, particularly in Italy, long afterwards. Frederick may have been near to victory when he succumbed to illness in 1250 and was entombed in Palermo.
Frederick became known as the Stupor Mundi, the Wonder of the World, for his excellence in administration, military tactics, science, and scholarship. However, his ruthlessness in pursuit of Empire made him disliked throughout his domains and throughout Europe. Furthermore, his battles with the Popes cost the Hohenstaufen line the Imperial power Frederick sought, since after his death the Church made certain to decrease his family's power. These battles also cost the Church prestige, for using its spiritual influence to wage an essentially secular war against a fellow Christian. This became a major symbol of the secularism in the Church which, despite attempts at reform, led to the Protestant Reformation and Catholic Counter-Reformation in the sixteenth century. Bibliographyeflst4@pitt.edu