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| 1921, Jan. 18 |
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| Beginning of British evacuation from northern Iran. Later that year in the south, the Iranian government oversaw the disbandment of the South Persia Rifles, assembled by Britain in 1916 as its special military force within the country. | 1 |
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| Feb. 21 |
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| Overthrow of the government by Riza Khan. The new regime included the prominent reformer Zia ud-Din as prime minister and Riza Khan himself as commander of the army. In his new post, Riza Khan assembled the first unified national army in Iran's history. The number of soldiers grew to approximately 127,000 by 1941. | 2 |
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| Feb. 26 |
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| Iranian-Soviet Treaty, which eliminated all tsarist concessions and Capitulations. The two countries further cemented their relations with a nonaggression pact on Oct. 1, 1927. | 3 |
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