Assadollah Hosseinpour () was born in 1882 or 1883 in Tehran, Iran. He was one of Ahad Agha Shirvani's three sons, and grandson of Moustafa Khan Shirvani, governor of the Shirvan Khanate), a descendant of the Shirvan Shah who fought against Shah Esmaeil from the Persian Safavid dynasty. Following the defeat of the Shirvan Shah, the Khanate of Shirvan was annexed to Persia, but Mustafa Khan retained the governorship of Shirvan. Hosseinpour's grandfather Mustafa Khan was a powerful landowner and a senior military commander in Shirvan. He married a Georgian princess while the khanates of Shirvan and Georgia were both parts of Persia. Georgia, Shirvan, and 15 other provinces or territories were later annexed to Russia, after three Russo-Persian Wars, during the Qajar dynasty, upon which the commanders of their armies, refusing to serve under the new Russian leadership, left their command posts and immigrated with their families to Persia, remaining loyal to the Shah of Persia. Military career Hosseinpour graduated in 1910 from the academy of the Persian Cossack Brigade, as one of its fourth graduating class. He was a classmate of the future General Fazllollah Zahedi (who became Prime Minister under Shah Mohammad Reza Shah Pahlavi in 1953) and Colonel Mehdi Gholi Tajbakhsh. On graduation from the academy, he performed his military duties under Rouhoullah Mirza for about two years and was then appointed Commander to the armies of the Iranian provinces of Azerbaijan and Kurdistan. He was later transferred to the Cavalry Division of the Persian Cossack Army and took part in World War I, during which he held the rank of lieutenant. At the end of the war, he was promoted to major. Along with a number of other Cossack commanders, Hosseinpour was a founding member of the new Imperial Iranian Armed Forces during the reign of Reza Shah Pahlavi. He headed the Cavalry Division in the February 21, 1921, coup headed by Reza Shah. He was one of a number of officers who reached and secured Tehran. Tehran was completely surrounded by a huge canal for protection against potential military invasion and robbers. A tall wall also encircled the city, with twelve huge metal gates that were locked at night and protected by military guards. The military force headed by the coup officers left Karaj, a town about 40 km from Tehran, and arrived at the Ghazvin Gate (close to the present Mehrabad International Airport).