The Gulf of Tonkin Resolution gave Johnson the authority to launch the first major military strikes on Vietnam and began a ten-year period of abject shame for the United States.
The Gulf of Tonkin Resolution was passed unanimously in the House of Representatives, but it was opposed in the Senate by two men, both were Democrats which mean they broke with their party in voting their consciences. Those Senators were Wayne Morse (Oregon) and Ernest Gruening (Alaska). During the debate on the Resolution, Senator Gruening told the Senate that he opposed "sending our American boys into combat in a war in which we have no business, which is not our war, into which we have been misguidedly drawn, which is steadily being escalated". He was, of course, 100% right in taking that stand.
Morse and Gruening opposed the Resolution for the most honourable of reasons, they believe that the war dishonoured America and, as it turned out, they were both right about that. They didn't do it to garner votes, or to go along with their political party and its leaders, or to gain the approval of their peers. Moral courage being defined as "the courage to take action for moral reasons despite the risk of adverse consequences," I regard those two votes as acts of courage; extremely rare among political leaders at the time. Rare even today.
Both men died in 1974, just after the Vietnam war ended. I am glad they saw their act of courage vindicated by events. We aren't all so fortunate.