Photos and text to accompany two versions of the Gulf of Tonkin Incident.

1. The Tonkin Gulf Incident

3. USS Maddox On Sunday Aug. 2, 1964 , three North Vietnamese torpedo boats attacked the American destroyer the USS Maddox in Southeast Asia's Gulf of Tonkin . Defense Secretary Robert McNamara told President Lyndon B. Johnson that a covert strike against North Vietnam two days earlier likely provoked the attack upon the Maddox.

4. Maddox Under Attack The three attacking North Vietnamese torpedo boats, as seen from the Maddox. The U.S. destroyer damaged two of the boats and sank the third. Retaliation by the Americans was limited to attacking those boats that day. The Maddox and another destroyer, the Turner Joy, were then deliberately positioned to draw a second attack.

5. Defense Secretary Robert McNamara Two days later, on Aug. 4 , McNamara reported to Johnson that an American destroyer in the region was under torpedo attack by the North Vietnamese . That brief conversation was the tipping point for the entire Vietnam War. Johnson ordered American forces to openly attack the North, and he asked Congress to pass a resolution pre-approving any military actions the president would take.

6. President Johnson Johnson on Aug. 4, 1964, announcing that the U.S. will retaliate against North Vietnam for two attacks on American destroyers in the Gulf of Tonkin. Later, Johnson and others would learn the second attack, which propelled the president and Congress to enter the Vietnam War, never happened.