Diocletian quit being emperor to grow vegetables, and his palace became a city
On 1 May 305, weakened by illness, Diocletian did something no Roman emperor had done before: he stepped down of his own accord. He retired to a vast palace on the Dalmatian coast near his birthplace and tended his vegetable gardens. That palace eventually grew into the heart of Split, in modern Croatia.
He started life as Diocles, from a low-status family, said to be the son of a scribe or of a senator's freed slave, and the first forty years of his life are largely a blank. Like other Illyrian soldiers of the era, he rose through the army. In 282 the emperor Carus put him in charge of the elite household cavalry. When Carus died on campaign in Persia and his son Numerian was found dead in his closed carriage, the army of the east hailed Diocles as emperor outside Nicomedia on 20 November 284. He blamed the prefect Aper for Numerian's death, killed him on the spot, and adopted the grander name Diocletianus.
He defeated Carus's other son, Carinus, at the river Margus in 285, helped by defections; Carinus was killed by his own men. Diocletian then set about ending decades of chaos. In 286 he named a fellow officer, Maximian, as co-emperor for the West, and in 293 added two junior emperors, creating the Tetrarchy, or rule of four. New capitals rose closer to the frontiers, at Nicomedia, Milan, Sirmium and Trier, and Rome's Senate lost its political weight.
He built the largest bureaucracy the empire had ever had, separated civil from military posts and from 297 standardised taxes at generally higher rates. His Edict on Maximum Prices of 301, meant to tame inflation, backfired and was quickly ignored. His persecution of Christians from 303, the last and largest, failed to stamp out the faith.
The Tetrarchy fell apart after his abdication as the sons of his colleagues fought over the succession. Even so, his reforms held the empire together for roughly another 150 years. He died around 311 or 312.
Source: Diocletian
