Diocletian is acclaimed Roman Emperor by his soldiers on November 17, 284 CE, (Some cite November 20), following the assassination of Emperor Numerian. During his reign, he restored efficient government to the empire after the near anarchy of the 3rd century and laid the foundation for the Byzantine Empire in the East, however it was marked by his orders for severe persecution of Christians.
Diocletian also introduced the "Tetrarchy", or "rule of four," in 293 CE; a system to stabilize the empire and handle massive borders more effectively, by dividing administrative power among two senior emperors (Augusti) and two junior emperors (Caesars). Caesars were intended to succeed the Augusti, creating a peaceful transfer of power. It aimed to curb civil wars, manage succession, The Empire was split into East and West, with each half governed by an Augustus and a Caesar. This allowed for faster, localized responses to revolts and threats. The system broke down into civil war after Diocletian's abdication on May 1, 305, leaving the Eastern Empire to Galerius and compelling his Western co-emperor, Maximian, to retire on the same day.
