In August 1964, the Johnson Administration claimed that the North Vietnamese military had attacked two U.S. destroyers in international waters. Within a week, Congress authorized the use of military force in Vietnam. While the resolution pointed to the Gulf of Tonkin incident as the reason for military action, other government documents show that President Johnson and military officials had been discussing military action in Vietnam before the event. In this lesson plan, students investigate whether or not the Johnson administration had been planning to go to war prior to the attacks.