How did the Roman tetrarchy contribute to the civil wars during Constantine I’s rise?

The Roman tetrarchy, established by Diocletian to ensure administrative stability and orderly succession, inadvertently fueled the civil wars during Constantine I’s rise by failing to account for the powerful influence of hereditary claims.12

The system relied on the voluntary abdication of the two senior emperors (Augusti) and the promotion of their deputies (Caesars). However, when the first tetrarchy ended in 305, the system collapsed because it bypassed the adult sons of the former emperors, such as Constantine (son of Constantius) and Maxentius (son of Maximian).213

This disregard for the hereditary principle triggered a series of power struggles:
* Usurpations: Following his father’s death in 306, Constantine was proclaimed Augustus by his troops, ignoring the tetrarchic rules. Simultaneously, Maxentius seized power in Rome, leading to a period where seven different individuals claimed the title of Augustus.13
* Systemic Breakdown: The tetrarchy’s attempt to replace hereditary succession with a meritocratic appointment process proved unsustainable, as the military and the populace remained deeply attached to the dynastic principle.2
* Successive Eliminations: The resulting confusion led to a series of civil wars as various claimants sought to consolidate power, ultimately leaving Constantine to defeat his rivals—including Maxentius at the Milvian Bridge—and eventually Licinius to become the sole emperor.134