Ngo Dinh Diem Assassination
South Vietnam
1963, Nov 02
President was arrested and assassinated in a CIA-backed coup.
After assassination, South Vietnam was unable to establish a stable government and several coups took place.
Sources
New Light in a Dark Corner: Evidence on the Diem Coup in South Vietnam
https://nsarchive.gwu.edu/briefing-book/vietnam/2020-11-01/new-light-dark-corner-evidence-diem-coup-november-1963
Books
Ember of War: The Fall of an Empire and the Making of America's Vietnam
by Fredrik Logevall