The Battle of Dyrrhachium (near present-day Durrës in Albania) takes place on October 18, 1081 between the Eastern Roman (Byzantine) Empire, led by the Emperor Alexius I Comnenus (r. 1081–1118), and the Normans of southern Italy under Robert Guiscard, Duke of Apulia and Calabria.

The battle is fought outside the city of Dyrrhachium (also known as Durazzo), the Byzantine capital of Illyria, and ends in a Norman victory.Following the Norman conquest of Byzantine Italy and Saracen Sicily, the Byzantine emperor, Michael VII Doukas (r. 1071–1078), betroths his son to Robert Guiscard's daughter.

When Michael is deposed, Robert takes this as an excuse to invade the Byzantine Empire in 1081.

His army lays siege to Dyrrhachium, but his fleet is defeated by the Venetians.

On October 18, the Normans engage a Byzantine army under Alexius I Comnenus outside Dyrrhachium.

The battle begins with the Byzantine right wing routing the Norman left wing, which breaks and flees.

Varangian mercenaries join in the pursuit of the fleeing Normans, but become separated from the main force and are massacred.

Norman knights in the center attack the Byzantine center and rout it, causing the bulk of the Byzantine army to rout.After this victory, the Normans take Dyrrhachium in February 1082 and advance inland, capturing most of Macedonia and Thessaly.

Robert is now forced to leave Greece to deal with an attack on his ally, the Pope, by the Holy Roman Emperor, Henry IV (r. 1084–1105).

Robert leaves his son Bohemond in charge of the army in Greece.

Bohemond is initially successful, defeating Alexius in several battles, but is defeated by Alexius outside Larissa.

Forced to retreat to Italy, Bohemond loses all the territory gained by the Normans in the campaign.

The Byzantine recovery begins the Komnenian restoration.