The Fourth Crusade was an expensive endeavor. Innocent III chose to raise funds with a new approach: requiring all clergy to donate one fortieth of their income. This marked the first time a pope ever imposed a direct tax on the clergy. He faced many difficulties in collecting this tax, including corrupt tax collectors and disregard in England. He also sent envoys to King John of England and King Philip of France, who pledged to contribute to the campaign, and John also declared his support for the clerical tax in his kingdom. The crusaders too contributed funds: Innocent declared that those who took the crusader's vow, but could no longer fulfill it, could be released by a contribution of funds. The pope put Archbishop Hubert Walter in charge of collecting these dues.