The gradual process of decline that brought the Roman Empire to an end is one of the all-time favorite history topics. That a nation so powerful could fall has always acted as a warning to any subsequent state that rose to a privileged geopolitical position. The ascension of Commodus in AD 180 is considered by many as the beginning of the end. But in reality, the exhaustion of Rome had started long before.
10. Unclear Succession System
Augustus, the first Roman emperor, could never establish a clear imperial succession system. The result: When the time came to replace an emperor, there were numerous rivals for the throne competing with one another.
Sometimes, the potential emperors had an incentive to end the service of the ruling emperor prematurely so that they could take the throne for themselves. This is part of the reason behind the long record of imperial assassination plots.
The imperial succession was a fragile, unstable system. Within the first 200 years of imperial tradition, Titus (r. AD 79–81) was the only emperor who succeeded his own father, Vespasian, and Commodus in AD 161 was the first emperor to be born to a ruling emperor, Marcus Aurelius (r. AD 161–180).