(Aug. 9, AD 378), battle fought at present Edirne, in European Turkey, resulting in the defeat of a Roman army commanded by the emperor Valens at the hands of the Germanic Visigoths led by Fritigern and augmented by Ostrogothic and other reinforcements. It was a major victory of barbarian horsemen over Roman infantry and marked the beginning of serious Germanic inroads into Roman territory.

The Goths annihilated the Roman army; by some accounts, the Romans lost 40,000 men. Valens, who had failed to await reinforcements from Gratian, his nephew and co-emperor, was killed on the battlefield. An accommodation (382) was reached with the Goths (Goth) by Theodosius I, Valens' successor as Eastern co-emperor, whereby the Goths agreed to aid in the imperial defenses in exchange for annual food subsidies, establishing a pattern for later barbarian intrusions into the empire.