The crisis began when Fritigern and the Thervingi Goths, fleeing the terrifying Huns, crossed the Danube seeking refuge. However, corrupt Roman officials exploited the refugees, forcing them into starvation. This mistreatment sparked a massive revolt that culminated in the Battle of Adrianople (378 AD). Emperor Valens, eager for glory, attacked without reinforcements and was killed, destroying two-thirds of the Eastern Roman army. This catastrophic defeat shattered the myth of Roman invincibility and opened the empire's borders.
As the frontiers collapsed, Alaric I united the Visigoths and demanded land and status. When Rome repeatedly betrayed these promises, Alaric besieged and finally sacked Rome in 410 ADโthe first time in 800 years the city had fallen to a foreign enemy. Meanwhile, the Vandals crossed the Rhine, swept through Gaul and Spain, and conquered North Africa. In 455 AD, they launched a seaborne raid on Rome, looting the city even more thoroughly than the Visigoths had.
The chaos deepened with the invasion of Attila the Hun, who ravaged Gaul and Italy until he was checked by a Roman-Visigothic alliance at the Battle of the Catalaunian Plains (451 AD). Finally, in 476 AD, the Western Roman Empire fell. Odoacer, a Germanic leader, deposed the last emperor, Romulus Augustulus. Breaking with tradition, Odoacer sent the imperial regalia to Constantinople, declaring that the West no longer needed an emperor. This act formally ended the ancient Roman line in the West.
Odoacer ruled Italy as a client of Constantinople, but his independence worried Emperor Zeno. Zeno incited Theoderic the Great, king of the Ostrogoths, to invade Italy. Theoderic defeated Odoacer in 493, killed him with his own hands, and established the Ostrogothic Kingdom, maintaining Roman administration under Gothic military rule.