Selected Chronology of U.S. Interest in Iran, 1951 - 1980

1908 Oil was discovered in Iran
1941 Britain and the USSR invaded Iran to prevent Iran from allying with the Axis powers during WWII. The Allies occupied Iran, took control of Iran's petroleum infrastructure,
and forced the Shah to abdicate in favor of his son, Mohammad Reza Pahlavi.
1951 Nationalist politician, Dr. Mohammed Mossadegh rose to prominence by spearheading a parliamentary movement to nationalize the British owned Anglo-lranian Oil Company (AIOC).
1953 The CIA, with help from British intelligence, planned, funded and implemented a coup to overthrow Mossadegh and elevate the Shah of Iran as the nation’s leader. The joint U.S.-British operation ended Iran's drive to assert sovereign control over its own resources.
1954 The Iranian government completed a contract with an international consortium of oil companies. The British lost the exclusive rights they had enjoyed previously by being reduced to 40 percent; another 40 percent went to American oil firms; and the remainder went to other countries. The British received a generous compensation for their former property.
1953-1979 For the next 25 years, the Shah of Iran became the United States' closest ally in the “Third World” by placing his country at the disposal of US military and intelligence, by allowing the U.S. to set up Soviet Union-electronic listening and radar posts near the Soviet border, and by allowing American aircraft to use Iran as a base to launch surveillance flights over the USSR and espionage agents to infiltrate across the border.
1977 President Carter toasted the Shah at a state dinner in Tehran, calling him "an island of stability" in the troubled Middle East. But the president knew that the Shah was in serious trouble. At the same time that opposition to his government increased, the Shah's dreaded secret service began to crack down on dissenters, fueling still more resentment. Within weeks of Carter's visit, a series of anti-American and anti-Shah protests broke out throughout Iran. 
1979 On January 16, the Shah fled to Egypt and two weeks later, the Muslim cleric Ayatollah Khomeini, returned to Iran after 14 years in exile and declared Iran an Islamic republic.
On November 4, Khomeini followers invaded the U.S. embassy in Tehran and took 66 Americans hostages. The hostage takers demanded that the Shah be extradited to Iran. President Carter refused and froze all Iranian assets in the U.S.
13 women and African Americans. They released one more hostage in 1980.1980 On April 11, Carter approved a high-risk rescue operation called "Desert One." Unfortunately, President Carter’s April rescue attempt failed. It began when six transport planes set off to rendezvous with a group of nine helicopters at a remote desert airstrip, southeast of Tehran. Soon thereafter, two helicopters went down with engine trouble, and a third was diverted to help. Another helicopter was damaged as it landed on the airstrip, leaving only five workable helicopters. President Carter ordered the operation to abort. As the aircraft took off again, another helicopter crashed into one of the C130 aircraft and burst into flames. Eight soldiers died, and another four men suffered burns.
In July, the Shah died and negotiations for the hostages' return began. However, nothing was worked out during Carter's administration.
1981 After 444 days in captivity, the remaining 52 hostages were released on January 20th, moments after the inauguration of Ronald Reagan as President of the U.S.
