Avar–Byzantine wars: The Avars lift the siege at the Byzantine stronghold of Tomis. Their leader Bayan I retreats north of the Danube River after the Avaro-Slavic army is decimated by the plague.

Maurice's Balkan campaigns were a series of military expeditions conducted by Roman Emperor Maurice in an attempt to defend the Balkan provinces of the Roman Empire from the Avars and the South Slavs. Maurice was the only East Roman emperor, other than Anastasius I, who did his best to implement determined Balkan policies during Late Antiquity by paying adequate attention to the safety of the northern frontier against barbarian incursions. During the second half of his reign, the Balkan campaigns were the main focus of Maurice's foreign policies, as a favourable peace treaty with the Persian Empire in 591 enabled him to shift his experienced troops from the Persian front to the region. The refocusing of Roman efforts soon paid off: the frequent Roman failures before 591 were succeeded by a string of successes afterwards.