Julian invaded the Sasanian Empire with a force of 95,000 men, hoping to secure the eastern frontier[2] and to replace Shah Shapur II with his brother Hormisdas.[3] He split his force in two, one under his cousin Procopius numbering 30,000 men,[4] which marched to northern Mesopotamia, and the other consisting of 65,000 men under his own leadership. Julian at first won a tactical victory outside Ctesiphon, but his army was too distracted with pillaging to take the city.[1] Julian burned the fleet which he had brought down the river to Ctesiphon,[1] and much of the baggage, leaving a bare three weeks supply. He then directed his march inland into the heart of Shapur's dominions, hoping to force a battle.