Gaius Aurelius Valerius Diocletianus (ca. December 22, 244 – December 3, 311), born Diocles (Greek: Διοκλής) an known as Diocletian (IPA: /ˌdаɪəˈkliːʃən/), was Roman Emperor from November 20, 284 to May 1, 305. Born to a Dalmatian family of low status, he rose through the ranks of the military to become cavalry commander to the emperor Carus. After the deaths of Carus and his son Numerian on campaign in Persia, Diocletian was acclaimed emperor by the army. A brief confrontation with Carus' other surviving son Carinus at the Battle of the Margus removed the only other claimant to the title. Diocletian appointed fellow-officer Maximian his Augustus, his senior co-emperor, in 285. He delegated further on March 1, 293, appointing Galerius and Constantius as Caesars, junior co-emperors. Under this "Tetrarchy", or "rule of four", each emperor would rule over a quarter-division of the empire. In campaigns against Sarmatian and Danubian tribes (285–90), the Alamanni (288), and usurpers in Egypt (297–98), Diocletian secured the empire's borders and purged it of threats to his power. In 299, Diocletian led negotiations with Sassanid Persia, the empire's traditional enemy, and achieved a lasting and favorable peace.