The Battle of Chrysopolis is fought on September 18, 324 at Chrysopolis (modern Üsküdar), near Chalcedon (modern Kadıköy), between the two Roman emperors Constantine I and Licinius.

The battle is the final encounter between the two emperors.

After his navy's defeat in the Battle of the Hellespont, Licinius withdraws his forces from the city of Byzantium across the Bosporus to Chalcedon in Bithynia.

Constantine follows, and wins the subsequent battle.

This leaves Constantine as the sole emperor, ending the period of the Tetrarchy.