The Fourth Lateran Council, and Two Crusades

The council Innocent summoned to the Lateran in November 1215 was attended by some four hundred bishops and eight hundred abbots and priors, with envoys from most of the kingdoms of Europe, and its seventy canons legislated for the whole of western Christendom. It defined the eucharistic change using the word transubstantiated, in what is the term's first conciliar use. It required every Christian who had reached the years of discretion to confess to their own priest at least once a year and to receive communion at Easter, which shaped the religious lives of ordinary people more than any other medieval enactment. It forbade the founding of new religious orders with new rules, and it regulated clerical conduct in detail.

It also imposed on Jews and Muslims in Christian territory a requirement to be distinguishable by their dress, and barred Jews from public office. That legislation is part of the council's record and the atlas states it plainly.

Two crusades belong to the reign and neither went as intended. He called the Fourth Crusade, which was diverted by its Venetian creditors first against a Christian city on the Adriatic and then against Constantinople, sacked in 1204. Innocent had expressly forbidden the attack and denounced it when he learned of it, then accepted the Latin empire that resulted, which is one of the reasons Greek Christians date the real breach with Rome to 1204. He also proclaimed the Albigensian Crusade against the Cathars of southern France in 1208, a campaign of twenty years that destroyed the culture of the region.