3 – Battle of Chrysopolis (AD 324)
This was the final battle between Emperor Constantine I and Emperor Licinius and took place on 18 September AD 324 in the city of Chrysopolis in what is now modern day Turkey. To the combatants, it probably appeared as if this was a battle of religions as Licinius had displays of Rome’s pagan gods in his battle lines whereas Constantine fought under the Christian standard.
Licinius was already on the back foot in the Second Civil War after suffering defeats at Adrianople and Hellespont. The Battle of Chrysopolis was a complete rout in favor of Constantine as he totally outwitted his opponent. Licinius is said to have lost up to 30,000 men in the battle and thousands more fled the battlefield.
The retreating Licinius knew he had no hope of victory and elected to throw himself at the mercy of his rival. Initially, Constantine showed mercy; perhaps because his enemy was married to his half-sister. However, he broke his solemn oath and executed Licinius a few months after Chrysopolis; presumably because he didn’t want any further rivals to his crown. To this end, he also had Licinius’ son executed the following year.
The battle had a major impact on the Roman Empire going forward. Constantine became the first sole emperor of Rome since AD 286 and soon after his victory, he decided to give the Eastern part of the Empire its own capital. The Emperor chose the city of Byzantium as the capital in the East which was renamed Constantinopolis. This city was to become the capital not only of the Roman Empire in the East but also of the brief Latin empire of the 13th century and the Ottoman Empire which followed the fall of Rome in the East.