He was instantly excommunicated by Gregory IX., and he replied by a proclamation addressed to all kings and princes,--a document breathing defiance and hate against the Pope and his claims. Nevertheless, in order to keep his word in regard to the Crusade, he went to the East with a large force in 1228, and obtained, by a treaty with the Sultan of Egypt, the possession of Jerusalem, Bethlehem, Nazareth and Mount Carmel, for ten years. His second wife, the Empress Iolanthe, was the daughter of Guy of Lusignan, the last king of Jerusalem; and therefore, when Frederick visited the holy city, he claimed the right, as Guy's heir, of setting the crown of Jerusalem upon his own head. The entire Crusade, which was not marked by any deeds of arms, occupied only eight months. Although he had fulfilled his agreement with Rome, the Pope declared that a crusade undertaken by an excommunicated Emperor was a sin, and did all he could to prevent Frederick's success in Palestine. But when the latter returned to Italy, he found that the Roman people, a majority of whom were on his side, had driven Gregory IX. from the city. It was therefore comparatively easy for him to come to an agreement, whereby the Pope released him from the ban, in return for being reinstated in Rome. This was only a truce, however, not a lasting peace: between two such imperious natures, peace was impossible. The agreement, nevertheless, gave Frederick some years of quiet, which he employed in regulating the affairs of his Southern-Italian kingdom. He abolished, as far as possible, the feudal system introduced by the Normans, and laid the foundation of a representative form of government. His Court at Palermo became the resort of learned men and poets, where Arabic, Provençal, Italian and German poetry was recited, where songs were sung, where the fine arts were encouraged, and the rude and warlike pastimes of former rulers gave way to the spirit of a purer civilization. Although, as we have said, his nature was almost wholly Italian, no Emperor after Charlemagne so fostered the growth of a German literature as Frederick II.