Battle of Adrianople, battle fought on August 9, 378 ce, near present-day Edirne, 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 elite Roman infantry and marked the beginning of serious Germanic inroads into Roman territory.
The emphatic defeat of Valens by the Goths at Adrianople revealed Roman vulnerability to attack from peoples beyond the imperial frontier. Fourth-century historian Ammianus Marcellinus wrote: “Never, since the Battle of Cannae, has there been such slaughter.”
Of Germanic origin, the Goths had settled territories to the north and west of the Black Sea. In the 4th century, they moved westward in great numbers, dislodged by the emergence of invading Huns from the Central Asian steppe. A group of Visigoths (Western Goths) called the Tervingi were allowed into the Roman Empire as immigrants to settle as foederati in frontier territories in Bulgaria and Thrace. The Ostrogothic (Eastern Goths) Greuthungi were denied permission to settle inside the empire, but they crossed the frontier with the Tervingi anyway. Relations with Roman officialdom deteriorated after the Greuthungi refused to depart, and in 376 the Goths rose in revolt.
Having taken control along the Danube, the Visigoths, led by Fritigern, and the Ostrogoths, commanded by Alatheus and Saphrax, moved on Constantinople. Valens, the Roman emperor in the east, had been campaigning in Syria when the revolt broke out, but he returned to Constantinople and led a large force out of the city to meet the Gothic forces. At Adrianople (now Edirne), they found Fritigern’s Visigoths camped atop a hill, their wagons ringing the summit in an impromptu fortress. Roman commanders launched the assault without waiting for the order to do so, sending two elite units into battle; infantry detachments that followed them came on piecemeal, throwing the attacking line off balance, and the Roman forces milled around in confusion. In this disordered state they were charged by Ostrogothic cavalry who, according to Ammianus, “descended from the mountain like a thunderbolt.” The Goths annihilated Valens’s Roman army; by some accounts, the Romans lost upward of 40,000 men. Valens, who had failed to await reinforcements from Gratian, his nephew and co-emperor, was killed on the battlefield. His body was never recovered.
Two-thirds of the eastern Roman army was destroyed at Adrianople, including a large number of experienced field officers. Yet, despite this defeat, by 382, under Valens’s successor Theodosius, the Romans drove the Goths back to Thrace and achieved peace.