1. THE END OF THE TETRARCHY

1. Stage 1

• 305 Maximian and Diocletian retire (die 310 and 312 respectively)
• Private life after being emperor was unprecedented 
• Diocletian’s retirement seems to have been willing - possible pressure from Galerius?
• Constantius and Galerius promoted to Augusti
• 2 new Caesares promoted: Maximin Daia and Severus
• Both close to Galerius: lends support to the Christian viewpoint that Galerius is the controlling agent
• Constantius and Maximian both have adult sons: Constantius and Maxentius
• Both overlooked: unusual for a biological son to be ignored in the succession
• cf. Adoptive principle only worked in 2nd century because emperors had no biological sons
• One of the only points in history where there was a genuine attempt to introduce a succession plan that overlooked biology in favour of merit 
• Vision only lasts for one generation; passing on of power falls apart after one generation
• Roman world cannot cope with biological sons being omitted/biological sons cannot cope with being omitted

• 306 Constantius, now Augustus in the West, dies; his troops proclaim Constantine as Augustus
• Difficult to reconstruct the narrative of events; first Christian emperor, Christian sources dominate late antiquity, therefore the narrative is unanimously pro-Constantine 
• Acclamation engineered by Constantius; recognised by Galerius
• Severus elevated to Augustus in the west
• Constantine acclaimed as Caesar 
• This leads Maximian’s son Maxentius aggrieved… revolts
• Maximian comes out of retirement to join sons’ revolt against Severus
• Severus’ troops refuse to fight, Severus imprisoned

• 307 Constantine allies himself with Maximian and Maxentius
• Married daughter of Maximian 

• 308 Diocletian comes out of retirement to form new tetrarchy 
• Licinius appointed by Galerius as Augustus
• Maximinus and Augustus named Caesar - junior position
• Maximinus and Constantine demand elevation to Augustus
• End up in situation with 4 co-emperors, rather than 2 senior and 2 junior 

• Diocletian’s system stabilises constant usurpation 
• Attempts to put down a stable succession falls apart almost immediately 
• Attempt to provide stability works for a generation but is a failure due to the inability to fix the main problem of the empire: the issue of succession 

1. Stage 2 

• 310 Maximian comes out of retirement… AGAIN (against own son)
• Tells troops that Constantine is dead and retreats to Marseille… commits suicide
• Problem for Constantine; draws his legitimacy from Maximian
• Constantine has to look for a new basis/claim to legitimacy 
• New narrative: appropriation of Claudius Gothicus 
• Claim to imperial authority based on his father having been an emperor, and Claudius Gothicus
• ‘third ruler after two rulers of your line’ based on familial dynasty rather than the tetrarchic system
• No other tetrarchic rulers can make this claim

• 311 Galerius dies - seems to have been holding things in check
• When Galerius dies, things fall apart… possibility of civil war
• Constantine and Licinus become allies and then each pick off another member of the tetrarchic college
• Licinius goes agains Maximin Daia
• Constantien goes against Maxentius

• 312 Constantine defeats Maxentius 
• Night before the battle, Constantine converts to Christianity and is thus victorious 

• 313 Maximinus Daia defeated by Licintus 
• Both battles report having been aided by religious aid 

• Now 2 Augusti.. but no Caesars. Indication both emperors are looking to dynastic rule, and probably both have ambition for sole rule

• 316 Fausta, Constantine’s second wife, daughter of Maximian, gives birth to Constantinus; catalyst for accelerating conflict between Licinus and Constantine

• Christian sources recall this as having been motivated by Constantine’s desire to stop Licinus persecuting Christians in eastern provinces
• More likely this is Constantine’s ambitions for dynastic rule being given a positive spin by later Christian authors

• 317 Uneasy peace, 2 Augusti and 3 Caesars 
• Pretence of alliance continues 

• 324 Constantine defeats Licinus, surrenders and executed
• Rome returns to having a single ruler 

• Political instability of the third century seems to have been ended temporarily by Diocletian’s tetrarchic reforms. 
• Constantine manages to rule the whole empire on his own, which no other emperor was able to due during the third century 

• Could be argued that he only managed to do this because the empire had been stabilised by the reforms of Diocletian
• How successful actually was Constantine’s rule? Based entirely on later Christian sources - bias

II. THE START OF A CHRISTIAN EMPIRE?

• Constantine takes an interest in church politics 
• Constantine calls church councils, first in 325