Answer:
The ouster of South Vietnamese President Ngo Dinh Diem in November 1963 had a significant negative impact on the South Vietnamese government and its ability to maintain stability and fight against the communist insurgency.
Firstly, Diem was a symbol of stability and continuity in the South Vietnamese government. His ouster by a military coup caused a power vacuum and a period of political instability, as a series of military and civilian leaders tried to fill the void left by his absence. This weakened the government's ability to make decisions and coordinate military and civilian efforts against the Viet Cong insurgency.
Secondly, Diem had established a strong personalistic regime, in which he controlled key positions in the government and military. His removal resulted in the dismantling of his political network and the loss of experienced and loyal officials, which undermined the government's effectiveness and further contributed to the political instability.
Thirdly, Diem was also a key figure in South Vietnam's alliance with the United States. The US had supported Diem's regime with financial and military aid, and his removal raised questions about the US commitment to South Vietnam's survival. This had a demoralizing effect on the South Vietnamese military and undermined their confidence in the government's ability to resist the communist insurgency.
Overall, the ouster of Diem had a negative impact on the South Vietnamese government and its ability to maintain stability and resist the communist insurgency. The political instability and loss of experienced officials weakened the government's effectiveness, while the loss of US support further demoralized the South Vietnamese military. This contributed to the eventual collapse of the South Vietnamese government and the fall of Saigon to the communists in 1975.