Diocletian

Diocletian (242/245–311/312), born Diocles to a low-status Dalmatian family, was Roman emperor from 284 to 305 and ended the Crisis of the Third Century. After Numerian's death, the army hailed him emperor outside Nicomedia; he accused Prefect Aper of murder and killed him. In 285 he defeated Carinus.

He made Maximian Augustus in 286 and in 293 created the Tetrarchy with Galerius and Constantius as Caesars. He secured the frontiers and made peace with Persia in 299. He standardised taxation; his Edict on Maximum Prices of 301 was ignored, and his persecution of Christians from 303 failed.

He abdicated in 305, the first emperor to give up office voluntarily, retiring to his Dalmatian palace, later the core of Split. When begged to return in 308, he is said to have replied that they would not ask if they could see the cabbages he had planted himself.