Coordinated Abdication and Succession

Diocletian had promised a new kind of monarchy: one that could plan its own end. On May 1, 305, he and Maximian kept the promise. In ceremonies at Nicomedia and Mediolanum, they took off purple and passed it on—Galerius and Constantius rose as Augusti; Severus II and Maximinus Daia entered the college as Caesars [16][11].

The choreography matched the constitution. No murder, no civil war, just the creak of ceremonial doors, the blare of bronze, and oaths spoken in cities far from Rome. The college remained balanced: East and West, senior and junior, each with assigned zones, each with a capital within reach of their enemies [16][11].

For administrators and soldiers alike, the message was powerful. Registers did not need rewriting; supply chains kept moving; diocesan vicarii kept sending files to the same prefectures. The purple was an office that could be relinquished on schedule. Subjects in Trier, Thessalonica, and Alexandria learned new names without learning new rules.

But abdication by design had a hidden vulnerability: it marginalized heredity. Constantius had a son—Constantine—who was not among the new Caesars. In Rome, Maximian had a son too—Maxentius—who watched the roster from a city that had been symbolically honored and practically displaced [16][11]. The schedule worked. Ambition took notes.