Freed from immediate external threats in the Balkans or in Anatolia, the Byzantine emperor John II Komnenos (r. 1118–1143) could direct his attention to the Levant, where he sought to reinforce Byzantium's claims to suzerainty over the Crusader States and to assert his rights of authority over Antioch. These rights dated back to the Treaty of Devol of 1108, though Byzantium had not been in a position to enforce them. The necessary preparation for a descent on Antioch was the recovery of Byzantine control over Cilicia. In 1137, the emperor conquered Tarsus, Adana, and Mopsuestia from the Principality of Armenian Cilicia, and in 1138 Prince Levon I of Armenia and most of his family were brought as captives to Constantinople.
Control of Cilicia opened the route to the Principality of Antioch for the Byzantines. Faced with the approach of the formidable Byzantine army, Raymond of Poitiers, Prince of Antioch, and Joscelin II, Count of Edessa, recognized themselves the emperor's vassals. John demanded the unconditional surrender of Antioch and, after asking the permission of Fulk, King of Jerusalem, Raymond of Antioch agreed to surrender the city to John. The agreement, by which Raymond swore homage to John, was explicitly based on the Treaty of Devol, but went beyond it. Raymond, who was recognized as an imperial vassal for Antioch, promised the emperor free entry to Antioch, and undertook to hand over the city in return for investiture with Aleppo, Shaizar, Homs, and Hama as soon as these were conquered from the Muslims. Then, Raymond would rule the new conquests and Antioch would revert to direct imperial rule.