After his dismissal, Topal Osman served briefly as governor of the Trebizond Eyalet and of Tiflis, before being recalled and, as the Empire's most experienced soldier, appointed "serasker" of Anatolia in the Ottoman–Persian War of 1730–35. In July 1733 he dealt a decisive defeat on the Persians, who under Nader Shah had invaded Iraq and were besieging Baghdad, at a hard-fought battle just north of Baghdad. Aided by Topal Osman's clever stratagems, the Ottomans inflicted some 30,000 casualties on Nader Shah's army and forced it to withdraw, although they lost 20,000 in turn. It was the only time that Nader Shah ever lost a battle.