In 1137, the Byzantines under Emperor John II, who still considered Cilicia to be a Byzantine province, conquered most of the towns and cities located on the Cilician plains. They captured and imprisoned Levon in Constantinople with several other family members, including his sons Ruben and T'oros. Levon died in prison three years later. Ruben was blinded and killed while in prison, but Levon's second son and successor, T'oros II, escaped in 1141 and returned to Cilicia to lead the struggle with the Byzantines. Initially, he was successful in repelling Byzantine invasions; but, in 1158, he paid homage to Emperor Manuel I through a short-lived treaty.