Answer
Dyrrhachium, a strategic city in present-day Albania, was successfully defended by Alexios I Komnenos against a Norman invasion led by Robert Guiscard in 1081. Alexios's victory at Dyrrhachium halted the Norman advance into the Byzantine Empire and preserved its territorial integrity. The battle marked a turning point in the Byzantine-Norman conflict, as it demonstrated the resilience of the Byzantine Empire under Alexios's leadership.