The crisis of the 3rd century was a period during which the Roman Empire nearly collapsed due to military invasions, revolts, civil wars, political instability, famine, and economic collapse. It began in 234 AD with the assassination of Alexander Severus and ended with the accession of Diocletian in 284. Let's get specific
————————————————The causes————————————————
Political instability - The imperial throne was a revolving door with a new Emperor taking the throne every couple of months. Most of them were either incompetent idiots or generals and this political instability caused the administration of the empire to disintegrate.
Civil wars - In the territories that remained part of the Roman Empire, civil war was the near-constant state of affairs for years
Revolt in the West - The provinces of Gaul and Britain declared independence as the “Gallic Empire”.
Invasions - Sassanid invasions, Dacian invasions, and Germanic invasions stretched imperial strength to its breaking point. The Sassanid invasion in the East was so successful that they captured the Roman Emperor in battle.
Revolt in the East - The Roman vassal city of Palmyrene was able to beat back the Sassanid invasion. As a reward the city was granted honors and status. Some years later the city revolted and took the Eastern provinces with them. This cut off grain supplies from Egypt and really damaged the imperial economy.
Famine - Disruption in the grain supply caused a total empire-wide famine.
Economic collapse - Obviously with the Empire tearing itself apart in a state of constant civil war, invasion, and revolt trade was severely disrupted and the economy collapsed.
————————————————The End————————————————
Into this mess stepped Emperor Aurelian in 270. A general of Illyrian descent who had spent his life commanding legions, his reputation was that of a cold, strict disciplinarian. First he defeated the barbarian invasions and secured Italy by having the Senate appoint him Emperor. He marched east and re-conquered the Palmyrene Empire and then headed West and conquered the Gallic Empire. With unity restored, the Roman economy began to rebound. Unfortunately, Aurelian was assassinated only a few years into his reign.
Shortly after Aurelian came Diocletian who radically reformed the empire. He literally altered every part of the empire and brought stability back to it. The capable and revolutionary reign of Diocletian marks and end to the crisis and an end to the Princeps period of the empire.
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