In AD 1453, the city of Constantinople, the capital and last stronghold of the Byzantine Empire, fell to the Ottoman Empire. By this time Egypt had been under Muslim control for some seven centuries. Jerusalem had been conquered by the Umayyad Muslims in 638, won back by Rome in 1099 under the First Crusade and then reconquered by Saladin's forces during the siege of Jerusalem in 1187. Later in the sevenths Crusade, it was taken back by the Catholics once again. It was conquered by the Ottomans in 1517. Orthodoxy, however, was very strong in Russia which had recently acquired an autocephalous status; and thus Moscow called itself the Third Rome, as the cultural heir of Constantinople. Under Ottoman rule, the Greek Orthodox Church acquired power as an autonomous "millet". The ecumenical patriarch was the religious and administrative ruler of the entire "Greek Orthodox nation" (Ottoman administrative unit), which encompassed all the Eastern Orthodox subjects of the Empire.