Congress overwhelmingly passes the Gulf of Tonkin Resolution (only 2 “no” Votes in the Senate; it passed the House unanimously), after U.S. boats were torpedoed in the Gulf of Tonkin (also known as the USS Maddox Incident) on August 2 and again on August 4. This gave Pres. Johnson, in his first year in office, almost unlimited power and “the right to take all necessary measures to repel any armed attack against the forces of the United States and to prevent further aggression."
Johnson used this resolution as his authority to escalate U.S. military involvement in the Vietnam War, and saw his popularity soar due to his “restrained handling of the crisis.” The Johnson Administration used this Resolution as their green light to begin heavy bombing and increase troops in Vietnam.
During the Nixon administration, the resolution was repealed, over Nixon’s objections. Realizing the need to restore limits on presidential authority to engage in war activity, Congress passed the War Powers Resolution in 1973 which requires the president to consult with Congress before engaging U.S. forces in hostile actions.