The Battle of Dyrrhachium (near present-day Durrës in Albania) took place on 18 October 1081, between the Byzantine Empire, led by the Emperor Alexius I Comnenus, and the Normans of Southern Italy under Robert Guiscard, Duke of Apulia and Calabria. The battle was fought outside the city of Dyrrhachium (also known as Durazzo), the Byzantine capital of Illyria, and ended in a Norman victory. Following the Norman conquest of Byzantine Italy and Saracen Sicily, the Byzantine Emperor, Michael VII, betrothed his son to Robert Guiscard's daughter. When Michael was deposed, Robert took this as an excuse to invade the Byzantine Empire in 1081. His army laid siege to Dyrrhachium, but his fleet was defeated by the Venetians. On 18 October, the Normans engaged a Byzantine army under Alexius I Comnenus outside Dyrrhachium. The battle began with the Byzantine right wing routing the Norman left wing, which broke and fled