The Battle of Damghan () or Battle of Mehmandoost (Persian: ) was fought on September 29 to October 5, 1729, near the city of Damghan. It resulted in an overwhelming victory for Nader Shah and the Safavid cause he had taken up, though by itself it did not end Ashraf's rule in Iran, it was a significant triumph which led to further successes in the following engagements of the campaign to restore Tahmasp II to the throne. The battle was followed by another one in Murcheh-Khort, a village near Isfahan. Nader's forces were victorious in both battles, which led him to remove the Ghilzai Afghan dynasty from their short stay on the Persian throne. The Hotakis were forced back to their territory in what is now southern Afghanistan.
The battle of Damghan proved the supremacy of Nader's artillery-dependent military system in comparison to the old exclusively cavalry based system utilised by the Afghans. Although Ashraf sought to remedy this in the subsequent engagement at Murcheh-Khort - relying on guns and artillery-men from the Ottomans - he failed to construct an adequate military structure to hold up against Nader's army.
Background
Ashraf having come to power in the aftermath of a coup against his predecessor, Mahmud Hotaki, had achieved great success in the war with the Ottomans where with a much inferior force he overcame a superior Turkish army and agreed to a settlement which divided the west of the former Safavid Empire of Iran with his Ottoman adversary in the aftermath of which he secured Turkish support and acceptance as the legitimate ruler of Iran.
Meanwhile, Nader & Tahmasp had been campaigning in the north-east building up a base from which to challenge Ashraf's claim on his newly acquired dominion. Hearing of the Nader's march on Herat, Ashraf set out from Isfahan in August 1729 with a host 30,000 strong, in the hope of conquering Khorasan while Nader was waging war on the Abdali Afghans further to the east. Unfortunately for Ashraf, Nader subjugated Herat and returned to Mashad before Ashraf could invade Khorasan. Upon hearing of Ashraf's approach Nader gathered his fighting men to set out via Sabzevar on September 12, 1729.
By the time Ashraf reached and besieged Semnan his force had grown to 40,000 compared to Nader's estimated strength of 25,000. Leaving a token force behind to resume the siege of Semnan Ashraf marched east towards Shahroud sending a fraction of his command ahead to seek out and destroy Nader's artillery. The first clash of arms between the two side occurred in a small but savagely fought skirmish south-east of Shahroud in which 14 Afghans were made prisoners whom were taken to Nader for interrogation. Nader continued to press forward until dusk, whence he began to make camp east of an obscure village by the name of Mihmandoost. That night Tahmasp promised him his sister's hand in marriage if Nader gained victory in battle on the following day.
Battle
Deployments & pre-engagement manoeuvres
In the morning of September 29, Ashraf drew up his army in the traditional fashion in three separate formations making up the centre, left and right as opposed to the Persian army which Nader had formed up in four divisions. Ashraf was so confident of victory that he set aside two to three thousand of his horsemen to hunt down and capture Tahmasp and Nader after his victory.
A rearguard of a few thousand mounted troops covered Nader's ongoing deployment to the left, on the Tal hills. In a break with conventional deployment patterns in oriental armies of this period Nader placed his artillery pieces behind his line infantry, where from their elevated positions on the high ground they overlooked the compact formations of Persian Jazāyerchi (musketeers) at the base of the hills as well as the valley in front of them. The Afghan left which had come into contact with the Persian rearguard and instead of pursuing them fell back in line with the rest of Ashraf's army when the rearguard was withdrawn. Ashraf gave the order for an all out charge driving his cavalry army of 40,000 riders towards the Persians whom were now awaiting at the foot of the Tal hills. The terrifying horde of Afghan riders charged forward with incredible speed and impetus.