Battle of Jalula was fought between Sassanid Empire and Rashidun Caliphate soon after conquest of Ctesiphon. After the capture of Ctesiphon, several detachments 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 theTigris 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, Khurasanand 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 CaliphUmar, Saad ibn Abi Waqqas reported all the matter to Umar. The Caliph decided to deal with Jalula first; his plan was first to clear the way north before any decisive action against Tikrit and Mosul. Umar appointed Hashim ibn Uthba to the expedition to Jalula. Some time in April 637, Hashim marched at the head of 12,000 troops from Ctesiphon and after defeating the Persians at the Battle of Jalula, laid siege to Jalula for seven months, until it surrendered on the usual terms of Jizya.[2]