Diocles was declared Emperor by the Danubian Legions on 285. As a foreshadow of the sweeping changes yet to come, Diocles changed this name to Diocletian. During the next some 20 years, this man of humble birth would radically change the empire in an attempt to halt its decay.

Diocletian's most major accomplishment was the creation of the Tetrarchy. In an attempt to reduce to burden of government, he created four co-rulers. Two Augusti (including himself) would rule of the two halves of the empire. While two Caesars would govern the frontier provinces and succeed the Augusti after their death. By enacting these reforms, Diocletian permanently split the empire asunder. The western or Latin half would one day crumble while the eastern or Greek half would survive. The number of provinces within the empire was also doubled by dividing existing provinces in half.

In another attempt to reduce the chances of internal disorder, Diocletian demanded that his subjects worship him. This attitude which was a trademark of the Persian royalty was meant to put the Augusti in a higher state. So that the ordinary people would be less inclined to questions his will and authority.

To remedy the problem of a bad economy, Diocletian tried to fix the value of prices. However his reforms did stop inflation from going up and only served to create a large underground black market. He also forced many citizens of the empire to stay at their respective occupations no matter what their desires were. This policy, in effect was the start of feudalism in Europe.

Finally in yet another attempt to unify the empire, Diocletian began to issue widespread restrictive laws on Christians. Although his wife was rumored to be Christian, Diocletian rightfully saw the Christian church as a threat. In later years his actions would be called the "Great Persecution" by the Christians.

Diocletians rule perhaps best marks the end of the Roman Empire. Although the empire would be united again, it would never fully recover its past glories. Soon, Constantine I would be the first Christian emperor and move his capitol from Rome to Constantinople.