Answer
Alexius I Komnenos, the Byzantine emperor from 1081 to 1118, was Bohemond's chief Byzantine adversary. Their conflict stemmed from Bohemond's ambitions to expand his territories in southern Italy and the Balkans at the expense of the Byzantine Empire. The rivalry between the two leaders culminated in the siege of Dyrrhachium in 1081, a decisive Byzantine victory that halted Bohemond's advances.