Diocletian was a Roman emperor at the end of the third century AD. He was chosen emperor by his troops on the 17th of September 284. In order to restore order in Gaul, and to prevent competition for the throne, he named his friend Maximian as coregent, and placed the western part of the empire under his rule.
Diocletian continued to directly govern the Asiatic part of the empire, and Egypt. He secured the state borders, and implemented a new territorial partition of the empire. He separated the military from civilian administration, and reconstructed the inner organization of the army and state bureaucracy. Diocletian took away from the Senate their former rights. Rome was no longer the capital. Then, in AD 293, Diocletian took another huge step into the unknown by founding the ‘Tetrarchy’, the rule of four. This new idea of imperial government meant that four emperors would rule the empire. But, this system eventually collapsed, leading to civil war.