The Iranian Revolution was a revolution that replaced a monarchy with a theocracy which is a system of government that use religion to create their rules and rights. The last Shah (Mohhamad Reza Pahlavi) was overthrown and was replaced by an Islamic Republic because he wanted to westernize and modernize Iran. His strong policy of westernization resulted in Iranian's opposing against him because they wanted Iran to be as cultural as it was. Some of the main causes of the revolution were defeat at war, peasant rebellion, national debt, and dissatisfied military.