Having married (1225) Yolande, daughter of John of Brienne, he claimed the crown of Jerusalem, but again postponed his departure on crusade. He further offended the pope by reasserting at the Diet of Cremona (1226) the imperial claim to Lombardy. The Lombard League was immediately revived, but open conflict did not break out until 1236. On the insistent demand of the new pope, Gregory IX, Frederick embarked on a crusade (Sept., 1227), but fell ill, turned back, and was excommunicated.
In 1228 he finally embarked. His "crusade," actually a state visit, was a diplomatic victory. At Jaffa he made a treaty by which Jerusalem, Nazareth, and Bethlehem were surrendered to the Christians, with the Mosque of Omar being left to the Muslims. In 1229 he crowned himself king at Jerusalem. The pope denounced the treaty by Frederick, who was still under excommunication, and sent a papal army to invade Frederick's kingdom. Frederick returned in 1229 and signed (1230) the Treaty of San Germano, by which he was temporarily reconciled with the pope.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.