Final answer:
The Gulf of Tonkin Resolution passed after reports of attacks on USS Maddox and USS Turner Joy, was the congressional authority used by President Johnson to escalate the Vietnam War. It was enacted on August 7, 1964, and granted president broad military powers without formal war declaration.
Step-by-step explanation:
The resolution passed by Congress, granting President Lyndon Johnson the authority to escalate U.S. military involvement in Vietnam following reported engagements with North Vietnamese forces, was the Gulf of Tonkin Resolution. This resolution, enacted on August 7, 1964, came after disputed incidents involving the USS Maddox and the USS Turner Joy in the Gulf of Tonkin.
The North Vietnamese attacks were used as justifications for a significant expansion of the U.S. role in the Vietnam War, despite later revelations that the August 4 attack likely never occurred. Nevertheless, Congress's nearly unanimous vote provided President Johnson with nearly unchecked power to combat perceived Communist threats without the necessity of a formal declaration of war.
The public was largely uninformed about the complexities of the incidents and the covert operations involved. The aftermath of the Gulf of Tonkin Resolution led to aggressive military actions, including aerial bombings and a significant troop deployment, which escalated the conflict into a full-scale war.