In 1742, news of Nadir Shah's victories in India caused alarm in the Ottoman Empire. In April of 1742, commanders along the frontier of Persia were alerted to the possibilities of a coming war. Nadir countered with demands of partial control of the Holy Cities, a demand that was completely unacceptable to the Sunni population. Mahmut I, heard of some military set backs for the Persians in the Daghistan region. He decided to place heavy tolls on Persian merchants; also, the Persian official assigned to escort Persians making the pilgrimage to Mecca was tortured and sent back to Persia.

Nadir decided that war was unavoidable and so he assembled an army estimated at 325,000 men. The Sultan Mahmut responded by issuing a fatwa, making it legal to kill all Persians whose religion was contrary to Islam (meaning death to all Shia). Mahmut also meddled in Persian internal politics by supporting one of two pretenders to the Persian throne, who came forward at this time.

Nadir decided to attack the city of Mosol first (located north of Baghdad, on the Tigris River). He razed every village along his invasion route, killing or enslaving all inhabitants regardless of their religious affiliation. Nadir established siege lines around Mosol by September 27 and commenced a bombardment of the city. The Persians had accumulated 160 cannons and 230 mortars to shell the city. The bombardment continued for eight days and there were numerous mining and counter-mining operations conducted during this period. Seven Persian assaults on the city were repulsed.

During this siege, Nadir received news that China was contemplating a declaration of war on Persia. Also, the two pretenders to the Persian throne began to pick up support and they threatened Nadir's hold on Persia. His invasion of Iraq in 1743 had accomplished nothing more than a devastating loss of lives in his attacks on Baghdad, Mosol and Kirkuk. Nadir now moved to the Caucasus and with the help of the local Anatolians he was able to usurp Ottoman rule in this region.

In August of 1745, the battle of Murad Tappa was fought, near the city of Qars. Nadir routed the Ottoman army of 150,000 men when he led an Abdalis contingent of his army, which numbered about 40,000, into the flank of the Ottomans. This attack resulted in the death of Yegen Pashan and all of the Ottoman artillery and baggage was lost. Nadir felt that he could now get favorable peace terms from the Ottomans. The general feeling in Persia was that they had suffered long enough and since all of the former Persian territory had been recovered through war, the hostilities should not continue.

Although they had suffered devastating losses of territory and manpower, the Ottomans refused to come to terms unless Nadir dropped his demands for the protection of Shias living in Ottoman territories. Nadir finally dropped these demands and a treaty was signed on September 4, 1746. Kasr-i-Sirn was once again the boundary.

More Ottoman Empire in the 18th Century

War With Persia 1723-1736
War With Austria and Russia 1736-1739
Resumption of the war with Persia 1742-1746
Russian War of 1768-1774