We don't celebrate the 4th July here in England, just like you guys in America don't celebrate the fall of Hanoi...
Just to keep history correct, Hanoi never fell. The Fall of Saigon (or Liberation of Saigon depending on your viewpoint) was the capture of Saigon, the capital of South Vietnam, by the People's Army of Vietnam and the National Liberation Front on April 30, 1975. The event marked the end of the Vietnam War and the start of a transition period leading to the formal reunification of Vietnam. Saigon is now formally known as Ho Chi Minh City.
BTW, Hanoi is now a brilliant travel destination, and a great place to shoot.