Yazdegerd III
After the death of his brother, Farrukhzad succeeded him as the "spahbed" of Khorasan and Adurbadagan, and as the new leader of the Ispahbudhan family and the "Pahlav" faction. He then raised an army at Adurbadagan, and went to Ctesiphon, where he was appointed as its commander by Yazdegerd III, who fled to Hulwan with his property, family and 1,000 servants. Farrukhzad, however, also fled to Hulwan after a small and disheartening clash with the Arabs. In 637, Ctesiphon was captured by the Arabs. Meanwhile, Farrukhzad, along with Yazdegerd III, the Mihranid officer Mihran Razi, Piruz Khosrow, and Hormuzan, left Hulwan for Adurbadagan, but while they were moving to the place, they were ambushed by an Arab army at Jalula, where they were defeated. Mihran Razi was killed during the battle, while Hormuzan had fled to Khuzestan and Piruz Khosrow to Nahavand. In 642, the Arabs captured Nahavand and Spahan, killing Piruz Khosrow including other Sasanian officers such as Shahrvaraz Jadhuyih and Mardanshah. During the same year (or in 643), Farrukhzad raised another army with his son Isfandyadh and the Dailamite general Muta. They were, however, defeated at Waj Rudh, a village in Hamadan. Meanwhile, Yazdegerd III fled to southern Iran and stayed there until 648. It is not known if Farrukhzad was with Yazdegerd III during his stay in southern Iran.