Having fired off this deadly missile Frederick resolved to perform his twelve-year-old promise and go upon a crusade. This was the Sixth Crusade (1228). It was as a crusade, farcical. Frederick II went to Egypt and met and discussed affairs with the Sultan. These two gentlemen, both of sceptical opinions, exchanged congenial views, made a commercial convention to their mutual advantage, and agreed to transfer Jerusalem to Frederick. This indeed was a new sort of crusade, a crusade by private treaty. Here was no blood splashing the conqueror, no “weeping with excess of joy.” As this astonishing crusader was an excommunicated man, he had to be content with a purely secular coronation as King of Jerusalem, taking the crown from the altar with his own hand—for all the clergy were bound to shun him. He then returned to Italy, chased the papal armies which had invaded his dominions back to their own territories, and obliged the Pope to grant him absolution from his excommunication. So a prince might treat the Pope in the thirteenth century, and there was now no storm of popular indignation to avenge him. Those days were past. In 1239 Gregory IX resumed his struggle with Frederick, excommunicated him for a second time, and renewed that warfare of public abuse in which the papacy had already suffered severely. The controversy was revived after Gregory IX was dead, when Innocent IV was Pope; and again a devastating letter, which men were bound to remember, was written by Frederick against the church. He denounced the pride and irreligion of the clergy, and ascribed all the corruptions of the time to their pride and wealth. He proposed to his fellow princes a general confiscation of church property—for the good of the church. It was a suggestion that never afterwards left the imagination of the European princes.