Since the United States never officially declare war on North Vietnam, the start date of the Vietnam War is open to debate. When the war began usually depends on which events one refers to. There are some probable dates which could possibly mark the start of the war:
November 1, 1955: Establishment of MAAG, Vietnam
The Indochina Military Assistance Advisory Group (MAAG) first established in Saigon on September 27, 1950 under President Harry Truman to aid the French Army in the First Indochina War was reorganized into the specific MAAG, Vietnam who essentially took over the French responsibility to train South Vietnamese Forces. In 1988, the U.S. Department of Defense (DoD) chose that as the start date to list American deaths during the Vietnam War.
March 1959: People’s War Declaration
At the begining of 1959, Ho Chi Minh called for a “People’s War” to unite North and South Vietnam. In May, a supply network best known as Ho Chi Minh Trail was constructed. On July 8, Major Dale R. Buis and Master Sargeant Chester M. Ovnand became the first Americans non-combat deaths in a guerillas strike at Bien Hoa. From North Vietnamese people’s perspectives, the second Indochina war against the U.S. officially began.
December 22, 1961: First U.S. Military Deployment & Combat Death
On December 11, the first U.S. military deployment took place as its aircraft carrier with 33 helicopters and 400 crewmen arrived in Saigon. On December 22, the first combat death was reported. For many Americans, the death marked the beginning of the War.
August 7, 1964: Gulf of Tonkin Resolution
In response to the Guft of Tonkin incident, the U.S. Congress passed the “Gulf of Tonkin Resolution” enabling President Johnson to take all necessary steps including the use of armed force to repel any armed attacks against the U.S. In other words, the President was allowed to wage a war against North Vietnam without ever having to obtain a formal declaration of war from Congress. Many regard the resolution as the “declaration” of the war, even though there was no official war declaration at all.
March 8, 1965: First U.S. Combat Units Arrival
The first U.S. combat units arrived in South Vietnam joining around 23,000 U.S. military advisers already there. Some Americans view the arrival of American combat troop as the start of the war even though their advisers had been in Vietnam for more than 10 years.