Mossadegh was involved in the 1924 Constitutional Revolution that was supposed to have ended autocracy in Iran and replaced it with a democratic republic. Instead, Reza Khan (Shah Reza) replaced the Qejars as as monarch. Later, Mossadegh rose to power because of rising anger at colonial deal between AOIC and Iran. His nationalization of AOIC triggered a balance of payments crisis for the UK, and two years later he was ousted by Operation Ajax. After he was overthrown, Shah Muhammad Reza was a dictator, and dependent on the USA to remain in power.