Reza Kahn (latter known as: Reza Shah), was an officer in Iran's only military force before the first world war "The Cossack Brigade". He'd use his troops to support a military coup against the Qajar dynasty. He'd become the emperor of Iran for the next 20 years.
Reza Shah would be forced to abdicate in exile from Iran in 1941 due to the Anglo-Soviet invasion. This would lead to his son Reza Pahlavi to become the new monarch of Iran.
Reza Pahlavi after 1941, went and put Iran on the map ( visited U.S a cup load of times and shakes hands with people ), and makes the Iranian government more promenent and out of the shadows by the end of the cold war (until 1980 that is).