Frederick II

Also known as Stupor Mundi

Stupor Mundi — the Wonder of the World — was the most powerful individual ever to wear the crown of Jerusalem. Grandson of Barbarossa, King of Sicily from infancy, Holy Roman Emperor from 1220, fluent in six languages including Arabic, polymath, naturalist and devoted hawker, Frederick II claimed the Jerusalem throne in 1225 through his marriage to Isabella II and treated the kingdom as another province of his Mediterranean empire. Pope Gregory IX, losing patience with the endless postponements of the crusade Frederick had sworn to lead, excommunicated him in 1227.

Excommunicated or not, he sailed in 1228 and achieved what no Crusader army had managed since Hattin. By the Treaty of Jaffa of February 1229 he negotiated the Ayyubid sultan al-Kamil — an old correspondent with whom he had been exchanging scholarly letters for years — into returning Jerusalem, Bethlehem, Nazareth and a corridor of pilgrim villages to Christian rule without a drop of blood being shed. Because no bishop in the Holy Land would crown an excommunicate, Frederick walked unescorted into the Church of the Holy Sepulchre on 18 March 1229, lifted the crown from the altar himself, and placed it on his own head while Hermann of Salza read the imperial declaration for him.

His local legacy was disaster. His attempt to impose imperial bailiffs — the “Lombards” — on the kingdom on his departure provoked the War of the Lombards (1229–1243), a fifteen-year civil war won in Acre and Cyprus by the Ibelin-led baronial party and producing the most fully articulated feudal constitution of the Middle Ages, the Assises de Jérusalem. Frederick never returned. His son Conrad II succeeded on paper; the kingdom was run from the High Court.

Preceded by John of Brienne. Succeeded by Conrad II.

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