November 7, 1979
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US President Jimmy Carter sends former Attorney General Ramsey Clark and Senate Intelligence Committee staff director William Miller to Iran to negotiate the release of the hostages. Ayatollah Khomeini refuses to meet with them.
https://www.cnn.com/2013/09/15/world/meast/iran-hostage-crisis-fast-facts/index.html
Sorry for the CNN sauce but it's the date that's important. Iran hostage situation.