1. Invasions by Barbarian tribes
The most straightforward theory for Western Rome’s collapse pins the fall on a string of military losses sustained against outside forces. Rome had tangled with Germanic tribes for centuries, but by the 300s “barbarian” groups like the Goths had encroached beyond the Empire’s borders. The Romans weathered a Germanic uprising in the late fourth century, but in 410 the Visigoth King Alaric successfully sacked the city of Rome. The Empire spent the next several decades under constant threat before “the Eternal City” was raided again in 455, this time by the Vandals. Finally, in 476, the Germanic leader Odoacer staged a revolt and deposed the Emperor Romulus Augustulus. From then on, no Roman emperor would ever again rule from a post in Italy, leading many to cite 476 as the year the Western Empire suffered its deathblow.
2. Economic troubles and overreliance on slave labor
Even as Rome was under attack from outside forces, it was also crumbling from within thanks to a severe financial crisis. Constant wars and overspending had significantly lightened imperial coffers, and oppressive taxation and inflation had widened the gap between rich and poor. In the hope of avoiding the taxman, many members of the wealthy classes had even fled to the countryside and set up independent fiefdoms. At the same time, the empire was rocked by a labor deficit. Rome’s economy depended on slaves to till its fields and work as craftsmen, and its military might had traditionally provided a fresh influx of conquered peoples to put to work. But when expansion ground to a halt in the second century, Rome’s supply of slaves and other war treasures began to dry up. A further blow came in the fifth century, when the Vandals claimed North Africa and began disrupting the empire’s trade by prowling the Mediterranean as pirates. With its economy faltering and its commercial and agricultural production in decline, the Empire began to lose its grip on Europe.
