Constantine was born into the military governing class of the late third century, the son of army officer Flavius Valerius Constantius “Chlorus” and his concubine Helena. The start of the fourth century was a turbulent time for the Roman Empire. After decades of civil wars and foreign invasions, Emperor Diocletian (r. 284–305) had tried to restore stability by introducing a system of government known as the Tetrarchy in 293. Each half of the empire, east and west, was governed by a senior emperor (Augustus) and a junior emperor (Caesar). Diocletian ruled the east with Galerius as his Caesar, while Maximian governed the west with Constantius Chlorus—Constantine’s father—as his junior.