In 1964, the USS Maddox was an intelligence-gathering naval ship stationed off the coast of North Vietnam for the purpose of gathering information about the ongoing conflict between North Vietnam and South Vietnam. The borders between the two sides were in dispute, and the United States was less up to date on changes in these borders than the two belligerents. In the process, the USS Maddox accidentally crossed over into North Vietnamese shores, and when the ship was sighted by North Vietnamese naval units, they attacked the Maddox on August 2, 1964.

Though no Americans were hurt, naval crews were on heightened alert as the Maddox retreated to South Vietnam, where it was met by the USS Turner Joy. Two days later, the Maddox and Turner Joy, both with crews already on edge as a result of the events of August 2, were certain they were being followed by hostile North Vietnamese boats, and both fired at targets popping up on their radar.

The fighting on August 2, can be verified through a variety of sources and an accounting of materials expended. However, the mystery of the Gulf of Tonkin begins with what the Maddox's Captain John J. Herrick believed was a second attack that spanned August 4 and into the following morning. He reported to officials that there was such an attack despite lack of visual confirmation. The Ticonderoga passed along the report of an August 4 attack, with some visual evidence gathered by sailors and officers.