Numerian

Numerian was proclaimed emperor by the Roman army in the East following the death of his father Carus during a campaign against the Sasanians. He was co-emperor with his brother Carinus, who ruled the West. Numerian's reign was brief and marked by his mysterious illness.

Numerian died under mysterious circumstances while traveling eastward from Persia. His death was concealed by the praetorian prefect Aper, who claimed Numerian was ill and kept him in a closed litter. The body's decomposition eventually revealed the death, leading to Aper's execution by Diocletian.

After Numerian's death was discovered, the army proclaimed Diocletian as emperor at Nicomedia. Diocletian personally executed Aper for the suspected murder of Numerian. This event marked the end of the Crisis of the Third Century and the beginning of the Tetrarchy.