What happened
Gothic groups admitted across the Danube in 376 under agreement were mistreated and exploited by Roman officials, and revolted. Two years of campaigning followed.
Valens advanced from Adrianople against Fritigern's wagon laager without waiting for the western army under Gratian, which was days away. Ammianus attributes the decision to a wish not to share the credit.
The Roman troops arrived after a long march in summer heat, without food, and were held in position while negotiations were attempted. Fires lit by the Goths added smoke and heat.
Fighting began before the negotiations concluded, and the absent Gothic cavalry returned and struck the Roman flank. The Roman line was compressed until, in Ammianus's description, men could not raise their weapons or draw their swords.
Tactics
The failures were operational rather than tactical: attacking without the converging force, committing exhausted troops without reconnaissance of the enemy's absent cavalry, and beginning an engagement during a parley. The compression of the Roman infantry into a mass too dense to fight is the same mechanism recorded at Cannae, and Ammianus's comparison is apt.
Consequence
The eastern field army had to be rebuilt. Theodosius settled the Goths inside the empire in 382 on terms allowing them to serve under their own leaders — a precedent with long consequences. The battle is often described as the moment cavalry displaced infantry as the dominant arm; that reading is not supported by the evidence and is treated below as a dispute.
Location
Outside Adrianople in Thrace
Modern: Near Edirne, Turkey
The city is certain; the battlefield has not been located.
Open questions
Did Adrianople mark the end of infantry dominance?
A view associated with older military history, notably Charles Oman, held that Gothic cavalry inaugurated a thousand years of mounted supremacy. Modern scholarship rejects it: the Gothic force fought largely on foot, late Roman armies remained infantry-based for centuries, and the defeat is better explained by operational error than by a change in the balance of arms.
Primary sources
Ammianus Marcellinus, Res Gestae 31.12-13
A contemporary account by a former staff officer, and one of the best-informed battle narratives in ancient literature.
How to read the evidence labels
- Evidence level: Documented
- Supported by a named primary text or by excavated material evidence.
- Evidence level: Probable
- Supported by strong inference that most specialists accept.
- Evidence level: Disputed
- Substantial specialist disagreement exists; competing readings are stated.
- Evidence level: Literary
- Belongs to poetic or mythological construction rather than to history.
- Evidence level: Mythological
- Belongs to shared religious or mythic tradition rather than to any single text.
- Evidence level: Unknown
- The available evidence is insufficient to decide.
These labels describe the status of the evidence, not our confidence in a conclusion. A claim marked Literary is not a claim we doubt; it is a claim about what kind of thing a poem is.