Why did the Roman Empire collapse? Didn't the Roman Empire have strong armies?
The Roman Empire lasted for either 503 years (from 27 BC, the start of the reign of the first Emperor Augustus , to the abdication of the last Western Roman Emperor Romulus Augustulus in 476), or 1480 years (from Augustus to the fall of Constantinople in 1453). Either time length is a remarkable achievement for a polyglot empire spanning a continent. But all things eventually come to an end, even empires. In the last couple of centuries of the (Western) Roman Empire, the army had become a massive cost to the empire. Worse, it was becoming obsolete. During that period, Rome faced to two major opponents: the Persian Empire to the east and German tribal confederations to the north. A good number of the Roman legions were tied to garrisons on the frontier. These soldiers were allowed to settle the land and become farmers. Consequently they were not motivated to protect other parts of the Empire. The Germans and Persians were developing more effective calvary tactics against the...