Ravaged by civil war and pressure from the Huns to the east, in late summer AD 376 the Gothic tribe of the Theruingi – up to 200,000 people under their leader Fritigern – gathered on the northern bank of the River Danube and asked the Eastern Roman emperor, Valens, for asylum within the empire. After agreeing to convert to Arian Christianity and enrol in the Roman Army, the Goths were allowed to cross the Danube and settle in the province of Thrace. Far more people crossed the Danube than the Romans expected, however, and with winter approaching, the local Roman commander, Lupicinus, lacked the resources to feed the newcomers and did not possess sufficient troops to control them. Treated poorly and running out of food, the Goths very quickly lost faith in the Roman promises.

Meanwhile, other Gothic tribes also sought permission to cross the Danube. The Greuthungi were refused permission, but soon learned that local Roman garrisons had been depleted to supervise the march of the Theruingi to the town of Marcianopolis, close to the eastern shore of the Black Sea. Taking advantage of this, the Greuthungi also entered Roman territory. Camping outside Marcianopolis, Lupicinus denied the Goths access to the town's food stores, provoking the Theruingi to begin skirmishing with the Roman troops. Fritigern convinced Lupicinus to let the Gothic leaders go and calm their people, but they did nothing to quell the warlike temper of his warriors. Lupicinus summoned troops to him, but in late 376 these Roman forces were defeated – the first of several defeats for the Romans that would culminate in the fateful battle of Adrianople in August 378, at which Roman forces led by the emperor himself confronted the Gothic host. The aftermath and repercussions of Adrianople have been much debated, but historians agree that it marks a decisive moment in the history of the Roman world. This fully illustrated book investigates the fighting men of both sides who clashed at the battles of Marcianopolis, Ad Salices and Adrianople, as the fate of the Western Roman Empire hung in the balance.