Background and Congressional action
President Johnson as he signs the resolution on August 10, 1964
The USS Maddox, a U.S. destroyer, was conducting a DESOTO patrol in the waters of the Gulf of Tonkin on August 2, 1964, when it reported being attacked by three North Vietnamese Navy torpedo boats from the 135th Torpedo Squadron, which were attempting to close their range on Maddox for effective torpedo fire (1,000 yards was maximum effective range for the torpedoes) Maddox fired over 280 5-inch shells and the boats expended their 6 torpedoes (all misses) and some 14.5-mm machinegun fire. Breaking contact, the combatants commenced going their separate ways, when the three torpedo boats, T-333, T-336, and T-339 were then attacked by four USN F-8 Crusader jet fighter bombers from the aircraft carrier USS Ticonderoga. The Crusaders reported no hits with their Zuni rockets, but scored hits on all three torpedo boats with their 20-mm cannons, damaging all three boats.
Two days later on August 4, Maddox and the destroyer Turner Joy both reported to be under attack again, by North Vietnamese torpedo boats; during this alleged engagement, Turner Joy fired approximately 220 3-inch & 5-inch shells at radar controlled surface targets. Hanoi subsequently insisted that it had not launched a second attack. A later investigation by the Senate Foreign Relations Committee revealed that Maddox had been on an electronic intelligence (DESOTO) mission. It also learned that the U.S. Naval Communication Center in the Philippine Islands, in reviewing the ships' messages, had questioned whether any second attack had actually occurred. In 2005, an internal National Security Agency historical study was declassified; it concluded that Maddox had engaged the North Vietnamese Navy on August 2, but that there may not have been any North Vietnamese Naval vessels present during the engagement of August 4. The report stated:
It is not simply that there is a different story as to what happened; it is that no attack happened that night. ...
In truth, Hanoi's navy was engaged in nothing that night but the salvage of two of the boats damaged on August 2. In 1965, President Johnson commented privately: "For all I know, our Navy was shooting at whales out there."
Within hours, President Johnson ordered the launching of retaliatory air strikes (Operation Pierce Arrow) on the bases of the North Vietnamese torpedo boats and announced, in a television address to the American public that same evening, that U.S. naval forces had been attacked. Johnson requested approval of a resolution "expressing the unity and determination of the United States in supporting freedom and in protecting peace in southeast Asia", stating that the resolution should express support "for all necessary action to protect our Armed Forces", but repeated previous assurances that "the United States ... seeks no wider war". As the nation entered the final three months of political campaigning for the 1964 elections (in which Johnson was standing for election), the president contended that the resolution would help "hostile nations ... understand" that the United States was unified in its determination "to continue to protect its national interests".
On August 6, U.S. Secretary of Defense Robert S. McNamara testified before a joint session of the Senate Foreign Relations and Armed Services committees. He stated that Maddox had been "carrying out a routine mission of the type we carry out all over the world at all times" and denied that it had been in any way involved in South Vietnamese patrol boat raids on the offshore islands of Hon Me and Hon Nieu on the nights of July 30 and July 31. The administration did not, however, disclose that the island raids, although separate from the mission of Maddox, had been part of a program of clandestine attacks on North Vietnamese installations called Operation Plan 34A. These operations were carried out by U.S.-trained South Vietnamese commandos under the control of a special operations unit of the U.S. Military Assistance Command, Vietnam called the Studies and Operations Group.
After fewer than nine hours of committee consideration and floor debate, Congress voted, on August 10, 1964, on a joint resolution authorizing the president "to take all necessary steps, including the use of armed force, to assist any member or protocol state of the Southeast Asia Collective Defense Treaty requesting assistance in defense of its freedom". (H.J. RES 1145 1964) The unanimous affirmative vote in the House of Representatives was 416–0. (However, Republican Congressman Eugene Siler of Kentucky, who was not present but opposed the measure, was "paired" with another member who favored the resolution—i.e., his opposition was not counted, but the vote in favor was one less than it would have been.) The Senate conferred its approval by a vote of 88–2. Some members expressed misgivings about the measure, but in the end, Democratic Senators Wayne Morse of Oregon and Ernest Gruening of Alaska cast the only nay votes. At the time, Senator Morse warned that "I believe this resolution to be a historic mistake."