This episode traces how the Gulf of Tonkin Resolution of 1964 became the legal basis for the Vietnam War. Lyndon B. Johnson wanted to protect his Great Society agenda and feared being branded soft on communism, as Democrats had been after China fell in 1949, while Barry Goldwater attacked the administration as weak. A formal declaration of war risked Chinese intervention, so in May 1964, months before any incident, officials including William Bundy and Walt Rostow drafted a resolution modeled on the 1955 Formosa Resolution. Offshore, South Vietnamese commandos ran Operation 34A raids under American support while DeSoto patrols such as the USS Maddox mapped the radar signals they provoked. On August 2, three North Vietnamese torpedo boats attacked the Maddox and were heavily damaged.

On the stormy night of August 4, sonar and radar operators on the Maddox and Turner Joy reported another attack, and the Turner Joy fired more than 200 shells while pilots overhead saw no enemy boats. Captain John Herrick cabled Washington urging caution, but Robert McNamara pressed for confirmation and told senators the Navy knew nothing of the commando raids. Johnson courted J. William Fulbright, who championed the measure on the Senate floor. It passed the House 416 to 0 and the Senate 88 to 2, with only Wayne Morse and Ernest Gruening opposed. Johnson used it to launch Operation Rolling Thunder in 1965, Congress repealed it in 1971, and the War Powers Resolution followed in 1973.

• Johnson later privately suggested the sailors may have been shooting at flying fish.
• Herrick concluded that propeller cavitation and weather effects likely produced false sonar and radar contacts.
• Johnson hinted that Fulbright could become his secretary of state after the 1964 election.
• Morse had been tipped off by a Pentagon source about the covert raids and called the resolution an unconstitutional transfer of war powers.
• Johnson called the resolution “grandma’s nightshirt” because it covered everything.