The Great Schism between the Eastern (Eastern Orthodox) and Western (Roman Catholic) churches came to a head in 1054, when papal legates excommunicated the Patriarch of Constantinople, who responded by excommunicating the legates. The main dispute, which had been building for several centuries, was the Pope's claims to authority over all the Church everywhere, rather than just over western Europe. Further controversies added to the schism included the West's addition of filioque to the Nicene Creed (the West saying the Holy Spirit "proceeds from the Father and from the Son"), the East's use of leavened bread in Communion, and - probably most significantly - general enmity after the East massacred Westerners in Constantinople and the West replied by sacking Constantinople itself in the Fourth Crusade.