Following Feb.22nd 1920 coup, the forth term of Majlis, most members of which were led by Modarres began its work; Modarres was a strong opponent to the minister of war, Reza Khan’s power seeking policies. Through some actions including the suppression of nomadic tribes of the country, the Jungle movement, Sheikh Khazal, Simitqu, Aboulqassem Lahuti and formation of an army with 40000 forces, Reza Khan established his political and military position. In November 1923, Ahmad Shah was appointed the prime minister. Having the support of Majlis members in his bill for the change of Iran’s regime to republic regime, the Shah cabled a telegram to him announcing his not having trust in him, he resigned from all his offices and left for Bumehen in protest. However, the organized demonstration of soldiers and the planned protest of the press ended in his coming back to Tehran.
At this time, Majlis agreed to Reza Khan’s request to command the army, and subsequent to some intrigues and moves by Reza Khan and the positive public opinion, the Majlis members ratified the overthrow of Qajar dynasty, and until the formation of Constituent Assembly they deposited the administration of the country with Reza Khan. The Constituent Assembly conceded the rule of Iran to Reza Khan in Nov. 21st 1925 and he became the Shah of Iran in May 1926.
iichs.ir/vdcj.yetfuqema29zu.html