Battle of Jalula
637 CE.
Shown on the map at 34.283°, 45.167°.
The Battle of Jalula was fought between the Sasanian Empire and the Rashidun Caliphate soon after the conquest of Ctesiphon by the latter. After Ctesiphon fell following a siege, several detachments of the Muslim army were immediately sent to the west to capture Qarqeesia and Heet, the forts at the border of the Byzantine Empire. Several strong Persian armies were still active north-east of Ctesiphon at Jalula and north of the Tigris at Tikrit and Mosul. The greatest threat of all was the Persian concentration at Jalula. After withdrawal from Ctesiphon, the Persian armies gathered at Jalula north-east of Ctesiphon, a place of strategic importance from where routes led to Iraq, Khurasan and Azerbaijan. The Persian forces at Jalula were commanded by General Mihran. His deputy was General Farrukhzad, a brother of General Rostam Farrokhzād, who had commanded the Persian forces at the Battle of Qadisiyyah. As instructed by the Caliph Umar, Saad ibn Abi Waqqas reported everything to Umar. The Caliph decided to deal with Jalula first; his plan was first to clear the way north before taking any decisive action against Tikrit and Mosul.
Text from the Wikipedia article Battle of Jalula, licensed CC BY-SA 4.0.