Soviet Invasion Of Khorasan
While the Soviets had attacked along their western border with Iran, their eastern border had remained silent. No orders had been received from Tehran, but the commanders of the Iranian 9th and 10th Divisions had taken proactive steps to protect their areas of responsibility to the best of their abilities. The 10th Division from Gorgan was probably the weakest Iranian Command, tasked with covering the expansive and largely deserted Golestan frontier. With a long featureless border squads of troops had been spread thin, to keep watch over the frontier along the Atrak River. The commander of the 9th Division, Major General Mohtashemi, deeper in country at Mashhad had considerably more men and resources at his disposal and was able to form two mobile strike groups and still leave two regiments of cavalry to defend Bojnurd in his northwest and Torbat-e Jam in his southeast.
Before dawn on the 11th September, the Soviet 53rd Army extended the conflict to the eastern shores of the Caspian Sea, crossing the frontier of the Atrak River at the border post of Ashk Tappeh. Iranian border guards offered no resistance, but were able to relay word of the advance to Gorgan, but the 10th Division’s troops in their tiny pockets offered minimal resistance to the opposing force and fled. Soviet armoured cars rapidly crossed the barren country side and captured Gorgan and Gonbad-e Qabus, taking control of the Plains of Gorgan up to the Alborz Mountains.
When news of the Soviet advance reached Mashhad, Mohtashemi dispatched one of his mobile columns east to defend the strategic Mazdavand Pass against a potential Soviet advance through Sarakhs, while the other was sent northwest, with orders to engage any Soviet force advancing south from Ashkhabad, requisitioning civilian vehicles to carry troops. The quiet in Mashhad did not last long though, as Soviet bombers from Ashkhabad soon struck at the Mashhad air base in force. The Iranian 3rd Air Regiment was not able to get any aircraft into the airborne, and the force was crippled on the ground. Hangars and facilities were destroyed and Iranian air power in the east was knocked out, although fierce anti-aircraft fire brought down several Soviet bombers.
With complete air superiority Soviet aircraft ranged unmolested over northeastern Iran, and caught the east-bound mobile group on the dirt road in transit to Mazdavand. Soviet Polikarpov I-16 fighters swooped down strafing the packed trucks and buses. In short order the Iranian column was smashed, and the battered survivors turned tail and struggled back to Mashhad.
The northern column ran into the Soviet 238th Rifle Division who had already passed though the Kopet Dagh and taken the town of Quchan. Under heavy artillery fire this column also turned and fell back to Mashhad, during which most of its officers and many men deserted and disappeared from the battle zone.
Finally by evening orders came through from Tehran, ordering a withdrawal of troops for a defence of the capital. Severely depleted now by desertions and having lost most of its motorised transport Mohtashemi gathered the remains of the 9th Division and started a night march westwards towards Tehran. In Golestan the sole remaining active unit of the 10th Division, the Iranian 23rd Cavalry Regiment, also received the pullback order and evacuated their fallback position along the Gorgan Gulf to join the defence of the capital.