"Diadumenian (/daɪˈædʊˌmiːniən/; Latin: Marcus Opellius Antoninus Diadumenianus) (September 14/19, 208 – 218), was briefly Roman Emperor from May to June 218. He was born to Macrinus, ...
his father, of which he was co-emperor, and Nonia Celsa, whose name may be fictitious, on 14 September 208. He was elevated to Caesar in May 217, and after Elagabalus revolted a few days later, Diadumenian was elevated to co-emperor. After Macrinus was defeated in the Battle of Antioch, on 8 June 218, Diadumenian was sent to the court of Artabanus V to ensure his safety; however, he was captured and executed along the way, in late June." - (en.wikipedia.org 21.06.2020)