What happen when diem was overthrown

South Vietnam's President Diem (which is who I'm assuming you're talking about) was overthrown in a military coup. Following the overthrow of his government by South Vietnamese military forces, President Ngo Dinh Diem and his brother are captured and killed by a group of soldiers. The death of Diemcaused celebration among many people in South Vietnam, but also lead to political chaos in the nation.