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The United States, recognizing the Viet Minh as a Communist menace, increases military aid to France in support of its anti-Viet Minh operations. Truman dispatches the Indochina Military Assistance Advisory Group to assist the French in Vietnam. They were not dispatched as combat forces, according to the President.
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In a speech, US President Dwight D. Eisenhower warns that the communist takeover of French Indochina could have a "domino" impact throughout Southeast Asia. For the following decade, the United States' views on Vietnam will be guided by the so-called domino theory.
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The French garrison at Dien Bien Phu, near the Vietnamese border with Laos, was overrun by Vietnamese troops led by General Vo Nguyen Giap. Vietnamese communist and nationalist forces have won a surprising victory, ending more than 70 years of French colonial domination in Indochina.
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In South Vietnam, the US starts a covert psychological warfare and paramilitary campaign. The operation is aimed at opponents of South Vietnam's newly installed Prime Minister, Ngo Dinh Diem. The Vietnam War officially begins on this date.
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At the 17th parallel, the Geneva Accords effectively divide Vietnam in half. Despite the fact that the accords clearly stipulate that the 17th parallel "shall not be regarded in any way as creating a political or territorial boundary," the 17th parallel immediately becomes a dividing line.
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Ngo Dinh Diem, a Catholic nationalist with US backing, becomes the leader of South Vietnam, while Ho Chi Minh controls the communist state to the north.
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In an effort to support guerrilla attacks against Diem's government in the south, North Vietnamese soldiers begin to create a supply route through Laos and Cambodia to South Vietnam. During the Vietnam War, the path becomes known as the Ho Chi Minh Trail, and it is considerably expanded and improved.
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Ngo Dinh Diem is assassinated by his own generals after the United States withdraws its support for him. Approximately 16,000 US military soldiers are now stationed in Vietnam, with 200 killed.
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The US destroyers Maddox and Turner Joy in the Gulf of Tonkin were assaulted by North Vietnamese torpedo boats, according to American leadership. The Gulf of Tonkin Resolution is passed by Congress, allowing President Lyndon B. Johnson to "take all necessary means to resist any armed attack against the United States forces."
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President Lyndon B. Johnson was empowered by the Gulf of Tonkin Resolution to "take all necessary measures to repel any armed attack against the forces of the United States and to prevent subsequent aggression" by North Vietnam's communist regime.
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In the hamlet of My Lai, U.S. Army troops massacre up to 500 defenseless people. Attempts to conceal the massacre begin almost as soon as the gunshots cease. In connection with My Lai, just one American, Lieutenant William Calley, will be found guilty of any wrongdoing.