After two hundred years of defeats and erosion, during which Byzantium lost virtually all of its possessions south of Asia Minor, the ascension of Basil I to the imperial throne in 867 marked a turnaround in Byzantine military fortunes. Byzantine armies beat back the Arabs in the east and south, and despite several humiliating defeats at the hands of the Muslims, reasserted dominance over the eastern Mediterranean. Syria, along with the key city of Antioch, also came back to Byzantine control, along with Armenia and large parts of the Balkans. For 150 years, Byzantium enjoyed civil prosperity and military victory. But new adversaries appeared where the old ones had fallen. In 1071, Byzantium suffered two catastrophic defeats -- they lost their last toehold in Italy to the Normans, who had earlier sacked Constantinople during a crusade gone awry. In the east, the Ottomans broke Byzantine power in Asia Minor forever at Manzikert, and the once dominant empire was reduced to a rump state comprising Constantinople, parts of the Balkans, and a few remaining provinces in western Turkey. The heart of it, though, was now ruled by the Turks. Nonetheless, during this time, art, religion, and philosophy flourished within the walls of Constantinople. It was as if the learned men of Byzantium were unaware of the threats lurking outside. Another fateful event, the Schism of 1054, finalized the separation between the Byzantine (Eastern) and Catholic (western) churches. This would lead to deep suspicion between the two churches, and western reluctance to assist Byzantium against the Turks years later. Eventually Byzantium was forced to resort to bribery and compromise with the Turks and the new western powers that coveted its territory and former influence. In 1421, after a hundred years of co-existence with the Turks, the new sultan Murad II revoked all of the arrangements that had existed between the two empires. As a last resort, the Byzantine emperor begged Rome for help, but the Christian army sent to fight the Turks was utterly defeated. In 1453, the Turks assaulted Constantinople itself, and the walls that had stood for over a thousand years finally fell, marking the end of the Byzantine Empire.