An old maritime tradition holds that the captain is the last to leave if a ship is evacuated. If a country evacuates an embassy in a country where the security situation has rapidly deteriorated or a hostile regime has taken over, and repatriate any other nationals willing and able to leave, does there exist any similar tradition or custom? Is the ambassador the last to leave the embassy / country in a case of evacuation?
In the evacuation of the American Embassy in Vietnam, 30th April 1975, The Ambassador was among the last civilians to be evacuated. But a contingent of Marines remained, to provide security as the Ambassador left.
The Ambassador evacuated at 4:58am, and the marines were evacuated at 7:53am of the same day.
Generally an ambassador is responsible for the organisation of matters in their embassy, and so for operational reasons the ambassador would be one of the last to leave. But the "last helicopter" will likely be carrying military, not civillians.