On November 4, 1979, thousands of Iranian protesters overran the US embassy in Tehran and took dozens of Americans hostage, marking the start of a lengthy crisis that came to define Jimmy Carter's single term as president.
Events leading up to the storming of the embassy had been decades in the making and were rooted in long-standing US support for Mohammed Reza Pahlavi, Shah of Iran.
Many Iranians condemned Washington's support of the autocratic shah and his “westernising” of the country.
In 1979, the shah was overthrown following years of brutality and corruption, and hardline Islamist Ayatollah Ruhollah Khomeini took power.
Mr Carter's administration permitted the shah to enter the US so he could undergo cancer treatment in New York - a decision that only exacerbated anti-American sentiments in Iran.
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Resentment boiled over on November 4, 1979, as throngs of militarised Iranian students broke into the US embassy and took 66 people hostage. Fourteen people were released over the following weeks and months, but 52 remained in detention.
With the 1980 presidential election looming, Mr Carter's administration was under intense pressure to secure the release of the hostages.
US news programmes beamed the crisis into American living room each night and kept a running tally of the number of days the hostages were detained.
The US cut diplomatic relations with Iran in 1980 after negotiations to secure the release of the hostages broke down, and a rescue mission authorised by the president failed and led to the deaths of eight American commandos.
It was a political disaster for Mr Carter, as Americans lost confidence in the Democratic president. He lost his re-election bid exactly one year after the crisis started, to California governor Ronald Reagan.
Mr Carter would later write in his memoir that the final weeks of his presidency were marked by a manic effort to secure their release.
On January 20, 1981, on the 444th day of the hostage crisis, Mr Carter was waiting for Iran to release the hostages as the US awaited the inauguration of Mr Reagan.
Mr Carter was informed after the inauguration that planes carrying the remaining US detainees had departed Tehran.
For Mr Reagan, who received word of their release not longer after he was inaugurated, it would be the first announcement he made as president.
