The Association for Diplomatic Studies and Training at the Foreign Service Institute just published an interesting account titled "When the Sudanese Autocrat Met President Reagan and Lost his Job" based on an oral history by William Pierce, political officer at the U.S. embassy in Khartoum at the time.
President Gaafar Muhammad Nimeiry had departed Khartoum for the United States for a meeting with President Ronald Reagan. Ambassador Hume Horan had also gone to Washington to participate in the meeting. I was charge d'affaires in Khartoum in the absence of the ambassador. Nimeiry was removed from power during his absence and did not return to Sudan until many years later.