There are two probable dates which could be considered as the end of the Vietnam War:
1. March 1973: On January 27, 1973, the United States, South Vietnam, North Vietnam and Viet Cong formally signed the Paris Peace Accords to end the war and restore peace in Vietnam. Under the terms of the agreement, an immediate ceasefire was established and the U.S. troops would be withdrawn altogether within 60 days. The accord officially ended direct American military involvement in Vietnam although some U.S. advisers still stayed in the South Vietnam until the fall of Saigon.
2. April 30, 1975: By early morning, North Vietnamese troops already occupied all important places in Saigon. Around noon, PAVN burst through the gates of South Vietnamese presidential palace. No sooner had the National Liberation Front (NLF) or Viet Cong flag been raised in the Independence Palace than acting President Duong Van Minh and his advisors were captured. Minh then broadcast an unconditional surrender and called for all ARVN troops to stop fighting. Later that afternoon, he declared South Vietnamese government and its military forces were “completely dissolved at all levels”.
Thousands of American and South Vietnamese civilians and military personnel were evacuated by helicopter before and after the event. Operation Frequent Wind carrying out on 29–30 April, for example, evacuated a total of 1,373 Americans and 5,595 Vietnamese and third-country nationals. The Vietnam War was officially over from the Vietnamese point of view. Vietnam became a unified and communist country since then.