Eastern Mediterranean 286: Diarchy of Diocletian and Maximian

Dec 284 Diocletian vs Carinus 1 Apr 286 Diarchy of Diocletian and Maximian 1 Mar 293 First Tetrarchy spr 297 Second Battle of Carrhae late 298 Galerius’ invasion of Persia 1 May 305 Second Tetrarchy

After suppressing the revolts in the West in early 285, Carinus marched east to meet Diocletian. Despite having superior numbers, when Carinus met his opponent near Margum, his troops abandoned him and he was killed by one of his own officers, leaving Diocletian as sole ruler of the Roman Empire. The following year Diocletian appointed his deputy Maximian as co-emperor to rule the West while he himself ruled the East.

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Jul 285 Battle of Margum ▲

In July 285 the Roman emperor Carinus advanced to meet the usurper Diocletian near Margum, on the Margus river, in Upper Moesia. Despite having superior numbers and apparently coming close to winning the battle, the emperor was abandoned by his own troops and defeated. Carinus died soon afterwards, possibly murdered by one of his own officers when he took refuge in the Danube fort of Cornacum (Sotin, Croatia), leaving Diocletian as sole ruler of the Roman Empire. in wikipedia

1 Apr 286–1 May 305 Co-reign of Maximian ▲

In July 285 Diocletian appointed his slightly younger deputy Maximian as Caesar and the following year promoted him to Augustus (co-emperor). Diocletian took the title Jovius (after Jupiter) and ruled at Nicomedia in the East, while Maximian took the subordinate title Herculius (after Hercules) and ruled from Augusta Treverorum (Trier) in the West. In 293, with the implementation of the Tetrarchy, Maximian moved to Italy and appointed Constantius as his Caesar in Gaul and Britain. When Diocletian abdicated in favor of his own Caesar, Galerius, in 305, Maximian also stepped down, entering a reluctant retirement. in wikipedia