Byzantine Empire
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Palestine, he allied himself with the Crusader Kingdom of Jerusalem and sent a large fleet to participate in a combined invasion of Fatimid Egypt. Manuel reinforced his position as overlord of the Crusader states, with his hegemony over Antioch and Jerusalem secured by agreement with Raynald, Prince of Antioch, and Amalric, King of Jerusalem respectively. In an effort to restore Byzantine control over the ports of southern Italy, he sent an expedition to Italy in 1155, but disputes within the coalition led to the eventual failure of the campaign. Despite this military setback, Manuel's armies successfully invaded the Kingdom of Hungary in 1167, defeating the Hungarians at the Battle of Sirmium. By 1168, nearly the whole of the eastern Adriatic coast lay in Manuel's hands. Manuel made several alliances with the Pope and Western Christian kingdoms, and
successfully handled the passage of the Second Crusade through his empire.
In the east, however, Manuel suffered a major defeat at the Battle of Myriokephalon, in 1176, against the Turks. Yet the losses were quickly made good, and in the following year Manuel's forces inflicted a defeat upon a force of "picked Turks". The Byzantine commander John Vatatzes, who destroyed the Turkish invaders at the Battle of Hyelion and Leimocheir, not only brought troops from the capital but also was able to gather an army along the way; a sign that the Byzantine army remained strong and that the defensive program of western Asia Minor was still successful.
John and Manuel pursued active military policies, and both deployed considerable resources on sieges and on city defenses; aggressive fortification policies were at the heart of their imperial military policies. Despite the defeat at Myriokephalon, the policies of Alexios, John and Manuel resulted in vast territorial gains, increased frontier stability in Asia Minor, and secured the stabilization of the empire's European frontiers. From c.1081 to c.1180, the Komnenian army assured the empire's security, enabling Byzantine civilization to flourish.
This allowed the Western provinces to achieve an economic revival which continued until the close of the century. It has been argued that Byzantium under the Komnenian rule was more prosperous than at any time since the Persian invasions of the seventh century. During the twelfth century, population levels rose and extensive tracts of new agricultural land were brought into production. Archaeological evidence from both Europe and
The Entry of the Crusaders into Constantinople, by Eugène Delacroix (1840).