When Manuel I was ruling the Byzantium, the east of the empire always attracted his diplomatic attention. The eastern strategy of Manuel dismissed the exterior crises of Byzantium successfully in 12 century: the extension of Latin forces and rising of Muslim forces. Under the reign of Manuel, the foundation of Byzantium Empire was laid and the territory of Comnenian Dynasty was expended to the maximum. But the eastern strategy of Manuel also had its defect. Endless war and consumption of diplomacy drained the national power of Byzantium, stimulated the domestic conflicts of the country and had Byzantium lost its control of the east.
Harris, J. (2014) Byzantium and the First Crusade: Three Avenues of Approach. Estudios Bizantinos, 2, 125-141.