17 September 19411941
British and Soviet forces occupied Tehran.

Three weeks after the start of the Allied invasion of Iran, British and Soviet forces entered Tehran. Iran had declared neutrality in World War II, but Britain and the Soviet Union had attacked the country from the north and south on the 3rd of Shahrivar 1320 (August 25, 1941).
The entry of Allied forces into the capital brought the pressure on Reza Shah's government to its final point.
One day later, Reza Shah abdicated, and Mohammad Reza Pahlavi succeeded him.