Why did Diocletian’s tetrarchy collapse after his abdication?

Diocletian’s tetrarchy, a system of four-man rule designed to ensure stability and orderly succession, collapsed shortly after his abdication in 305 CE primarily because it failed to account for the powerful influence of hereditary claims.1

While Diocletian sought to replace natural succession with a meritocratic system where two senior Augusti would retire and be succeeded by their junior Caesars, he underestimated the attachment of both the military and the general population to the hereditary principle. When Constantius I died in 306 CE, his troops ignored the established tetrarchic rules and proclaimed his son, Constantine I, as Augustus. Simultaneously, Maxentius, the son of the retired Augustus Maximian, also claimed power, effectively triggering a period of civil war and confusion as multiple claimants vied for the title of Augustus.12

Ultimately, the system proved to be a transitory arrangement that could not survive the transition of power without the personal authority and statesmanship of Diocletian himself.1