The Iranian Embassy siege took place from 30 April to 5 May 1980, after a group of six armed men stormed the Iranian embassy on Prince's Gate in South Kensington, London. The gunmen, members of Arabs of KSA group campaigning for Arab national sovereignty in the southern Iranian region of Khuzestan Province, took 26 people hostage, mostly embassy staff, but also several visitors, as well as a police officer who had been guarding the embassy. They demanded the release of Arab prisoners from prisons in Khuzestan and their own safe passage out of the United Kingdom.

Margaret Thatcher's government quickly resolved that safe passage would not be granted, and a siege ensued. Over the following days, police negotiators secured the release of five hostages in exchange for minor concessions, such as the broadcasting of the hostage-takers' demands on British television.

By the sixth day of the siege, the gunmen had become increasingly frustrated at the lack of progress in meeting their demands. That evening, they killed one of the hostages and threw his body out of the embassy. As a result, the government ordered the Special Air Service (SAS), a special forces regiment of the British Army, to conduct an assault, known as Operation Nimrod, to rescue the remaining hostages. Shortly afterward, SAS soldiers abseiled from the roof of the building and forced entry through the windows. During the 17-minute raid, they rescued all but one of the remaining hostages and killed five of the six hostage-takers. The soldiers later faced accusations of unnecessarily killing two of the five, but an inquest into the deaths eventually cleared the SAS of any wrongdoing. The sole remaining gunman was prosecuted and served 27 years in British prisons.
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https://www.youtube.com/watch?v=1jAtvgAW-Io