Prelude[edit]
After the capturing Ctesiphon, several detachments were immediately sent west to capture Qarqeesia and Heet, forts at the border of Byzantine empire. Strong Persian garrisons north-east of Ctesiphon at Jalula and north of Tigris at Tikrit and Mosul, were threat to Muslim invaders. The greatest threat of all was the Persian concentration at strategic fort of Jalula. The Persian forces at Jalula were commanded by general Mihran Razi. His deputy was General Farrukhzad a brother of General Rostam Farrokhzād, who commanded Persian forced at Battle of Qadisiyyah. Jalula was a town of great strategic importance, a bottle-neck to Northern Iraq. To have Jalula under the rule meant to have the gate to Northern Iraq. Persians therefore expected an attack on Jalula. Defense of Jalula was also very important for the strength of Empire and maintain order in the far flung frontiers of the Persian Empire. As instructed by the Caliph Umar, Saad ibn Abi Waqqas, Muslim commander in chief on Persian front, reported all the strategic situation to Umar. Who decided to deal with Jalula first, his plan was first to clear his rear before any decisive action further north against Tikrit and Mosul. Umar appointed Hashim ibn Uthba to the expedition of Jalula. Some time in April 637, Hashim marched at the head of 12,000 troops from Ctesiphon and made contact with Persians out side Jalula fort.[2]