History of the Roman Empire disputes about the supreme authority, this finally formalised a peaceful succession of the emperor: in each half a "Caesar" would rise up to replace the "Augustus" and select a new "Caesar". On May 1, 305, Diocletian and Maximian abdicated in favour of their "Caesars". Galerius named the two new "Caesars": his nephew Maximinus for himself, and Flavius Valerius Severus for Constantius. The arrangement worked well under Diocletian and Maximian and shortly thereafter. The internal tensions within the Roman government were less acute than they had been. In "The Decline and Fall of the Roman Empire", Edward Gibbon notes that this
Fall of the Western Roman Empire of Commodus, after a number of introductory chapters. Arnold J. Toynbee and James Burke argue that the entire Imperial era was one of steady decay of institutions founded in republican times, while Theodor Mommsen excluded the imperial period from his Nobel Prize-winning "History of Rome" (1854–56). As one convenient marker for the end, 476 has been used since Gibbon, but other key dates for the fall of the Roman Empire in the West include the Crisis of the Third Century, the Crossing of the Rhine in 406 (or 405), the sack of Rome in 410, and the death of Julius