May 1961: President John F. Kennedy sends helicopters and 400 Green Berets to South Vietnam and authorizes secret operations against the Viet Cong.
November 1963: President Kennedy is assassinated in Dallas, Texas. Lyndon B. Johnson becomes president.
February 1965: President Johnson orders the bombing of targets in North Vietnam in Operation Flaming Dart in retaliation for a Viet Cong raid at the U.S. base in the city of Pleiku and at a nearby helicopter base at Camp Holloway.
July 1965: President Johnson calls for 50,000 more ground troops to be sent to Vietnam, increasing the draft to 35,000 each month.
1966: U.S. troop numbers in Vietnam rise to 400,000. 1967: U.S. troop numbers stationed in Vietnam increase to 500,000.
February 1967: U.S. aircraft bomb Haiphong Harbor and North Vietnamese airfields.
March 1968: President Johnson halts bombing in Vietnam north of the 20th parallel.
November 1968: Republican Richard M. Nixon wins the U.S. presidential elections on the campaign promises to restore “law and order” and to end the draft.
December 1972: President Nixon orders the launch of the most intense air offense of the war in Operation Linebacker.
