In 1954, the Vietnamese defeated the French forces, and the two sides agreed to a temporary, 2-year partition of Vietnam at the 17th parallel, with the French military forces retreating to the south before elections were held and a unified government could be established. The US government publicly supported that plan but privately provided funding and other support for the development of an independent, anticommunist, pro-American state in the south, the Republic of Vietnam. In the late 1950s, the government of North Vietnam, the Democratic Republic of Vietnam, ratcheted up its efforts to take over South Vietnam and merge the two countries; in 1960, it established the National Liberation Front (the NLF, commonly known to Americans as the Viet Cong) to fight against the South Vietnam government (Appy, 1993; Marolda, 1994). In August 1964, shots were allegedly fired at the American destroyer USS Maddox off the coast of North Vietnam in the Gulf of Tonkin, where it was conducting intelligence-gathering on behalf of the Republic of Vietnam. President Lyndon Johnson ordered retaliatory air strikes on North Vietnam, and Congress later passed the Gulf of Tonkin Resolution, sending large numbers of US troops to Vietnam. US troop levels in South Vietnam rapidly rose from 23,000 ground troops in 1964 to 185,000 in 1965 and peaked in 1968 with 536,000 ground troops (Appy, 1993).
In early 1968, the “Tet Offensive” campaign by the NLF and South Vietnamese irregulars began a period of intense fighting (Turley, 2009) and helped to turn an already disillusioned American public more sharply against the war. President Johnson ordered a slow withdrawal of American troops from Vietnam. American troop withdrawal began in 1969, and the transfer of military equipment and leadership responsibilities to the South Vietnamese government (known as the Vietnamization of the war effort) became a larger focus of the American military. American troop levels decreased rapidly thereafter, and in 1973 after the Paris Peace Accord, virtually all remaining American troops were withdrawn. Fighting continued between North Vietnam and South Vietnam, however, until April 30, 1975, when Saigon, the capitol of South Vietnam, was captured by the North Vietnamese, and the South Vietnamese army surrendered.
The Blue Water Navy commonly refers to ships designed for open-ocean sailing and by association to the sailors assigned to those ships.