Innocent now called a general council of the Church--the Fourth Lateran Council, 1215--for the purpose of stimulating a new crusade. "The necessity for succoring the Holy Land," said his letters of convocation, "and the hope of conquering the Saracens, are greater than ever. We renew our cries and our prayers to you to excite you to this noble enterprise."
The Sixth Crusade, which was inspired by the Pope and preached in France by his legate, Robert de Courçon, was divided in the sequel into three maritime expeditions. The first, 1216, consisted mainly of Hungarians under their King, Andrew; the second, 1218, was composed of Germans, Italians, French, and English nobles and their followers; and the third, 1228, was led by Frederick II in person. The first two produced no considerable advantage for the Christians; while Frederick, involved in the Hohenstaufen struggle with the papacy, evaded his crusading vows made long before. Innocent III died in 1216; Honorius III, the next pope, died in 1227; and his successor, Gregory IX, urged Frederick on to fulfil his promise. The Emperor embarked in 1227, but when he had been only three days at sea, by reason of his own illness or the sickness of his troops--accounts are not agreed--he returned to port. The Pope, furious at his conduct, excommunicated him. But in the following year, notwithstanding the ban, Frederick set sail for Palestine, and the story of this expedition is the essential history of the Sixth Crusade.
After his excommunication, Frederick appealed not to the Pope, but to the sovereigns of Christendom. His illness, he said, had been real, the accusations of the Pope wanton and cruel. "The Christian charity which should hold all things together is dried up at its source, in its stem, not in its branches. What had the Pope done in England but stir up the barons against John, and then abandon them to death or ruin? The whole world paid tribute to his avarice. His legates were everywhere, gathering where they had not sown, and reaping where they had not strawed."
But although he thus dealt in language as furious as that of the Pope, the thought of breaking definitely with him and of casting aside his crusading vow as worthless mockery never seems to have entered his mind. He undertook to bring his armies together again with all speed, and to set off on his expedition. His promise only brought him into fresh trouble with the Pope, who in the Holy Week next following laid under interdict every place in which Frederick might happen to be. If this censure should be treated with contempt, his subjects were at once absolved from their allegiance.