Fall of the Western Roman Empire
Battle of Adrianople

In 376, the East faced an enormous barbarian influx across the Danube, mostly Goths, who were fleeing from the Huns. They were exploited by corrupt officials rather than effectively relieved and resettled, and they took up arms and were joined by more Goths and some Alans and Huns. Valens was in Asia with his main field army preparing for an assault on the Sasanian Empire. Redirection of the army and its logistic support would have required time, and Gratian's armies were distracted by Germanic invasions across the Rhine. In 378, Valens attacked the invaders with the Eastern field army, now perhaps 20,000 men, probably much fewer than the forces that Julian had led into Mesopotamia a little over a decade before, and possibly only 10% of the soldiers nominally available in the Danube provinces. In the Battle of Adrianople (9 August 378), Valens lost much of that army and his own life. All of the Balkan provinces were thus exposed to raiding, without effective response from the remaining garrisons who were "more easily slaughtered than sheep". Cities were able to hold their own defensive walls against barbarians who had no siege equipment, therefore the cities generally remained intact, although the countryside suffered.
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