 He ordained a Latin rite priest and at the invitation of Innocent III of Rome, sent representatives to participate in the Fourth Lateran Council (1215).In 1218–1219, Crusaders captured Damietta as a base to invade and liberate the Christians of Egypt from the Ayyubid Muslims.After a crushing defeat in 1221, Crusaders surrendered Damietta and signed an 8-year truce.