A series of political and military setbacks starting as early as 1962 had been gradually eroding the combat effectiveness of the ARVN forces, originally more than a match for the VC with their United States supplied helicopters and armored personnel carriers.

The VC forces had been left to train in relative safety and had developed new tactics and been supplied with new weapons that upset the balance of power.

They set about building up a fortified area on a nearby hill and were joined by the POW intelligence team, 120 ARVN, and several light tanks manned by local militiamen.

At 01:45 on May 10, the VC 761st and 763rd Regiments consisting of 2,500 infantry attacked the city from multiple directions, first using mortar barrages and then rushing in their forces.

Attempts to evacuate casualties by helicopter were repeatedly driven off by 50-caliber machine guns, until these were suppressed by F-4 Phantoms using cluster munitions.