The U.S. Embassy in Tehran was overrun twice.1st overran, a group of heavily-armed the Iranian Revolutionary Marxists the Fedayeen-e Khalq,invaded the U.S. Embassy compound in central Tehran in a hail of gunfire and held the staffers hostage for few hours. only four days after the overthrow of the Mohammad Reza Pahlavi, the shah of Iran, on Valentine’s Day, February 14,1979. It was carried out by hundreds of militants clambered over the walls and poured through the breached gate of the large compound on Takht-e Jamshid Street (now called Taleghani Street).
On November 4,1979. 2en overrun, a group of Iranian students, belonging to the Muslim Student Followers of the Imam's Line, who were supporting the Iranian Revolution, stormed the U.S. Embassy in Tehran and took 52 American American diplomats hostage.
The hostages would be released only when the Shah came back to Iran to stand trial for crimes committed against the Iranian people.The Iranians held the American diplomats hostage for 444 days.