Which battle in 378 CE ended with the death of Roman emperor Valens?

The Battle of Adrianople in 378 CE ended with the death of Roman emperor Valens.

The battle was fought near Adrianople, in modern-day Edirne, Turkey, between the eastern Roman army led by Valens and a Gothic force commanded by Fritigern. The Goths had entered Roman territory after crossing the Danube, and tensions worsened because of mistreatment, food shortages, and corrupt administration.

Valens marched from Constantinople and chose to attack before reinforcements led by the western emperor Gratian arrived. Roman cavalry initially made progress, but the Gothic wagon laager and returning Gothic cavalry helped encircle the Roman army. The Roman defeat was catastrophic, and Valens was killed; his body was never definitively identified.

Adrianople did not immediately end Roman rule in the Balkans, but it exposed serious weaknesses in imperial military management. It is often compared with Cannae because of the scale of the defeat. The battle also helped shape the later settlement under Theodosius I, who admitted Goths into the empire as a semi-autonomous people in 382.