On August 23, 1968, an NVA/VC sapper attack was launched on a SOG compound in Da Nang, FOB (forward operating base) 4. Seventeen Green Berets were killed during that attack—the single largest toll of Green Berets killed in Special Forces history.
The communist forces planned the attack for more than a year. When they attacked FOB 4, they did so shortly after midnight, at a time when the compound’s base population swelled with more than 100 Green Berets appearing before a promotion board. Additionally, the monthly SOG staff meeting of all six FOB commanders and S-2/S-3 personnel was held the day before. Last, but not least, the SOG Command and Control staff stationed near the Da Nang Air Base had been moved into FOB 4, and operated out of the headquarters office.
By August 1968, SOG’s secret war had been going on for four years. Unknown to SOG brass was just how deeply the communist forces in Vietnam had infiltrated SOG and its bases, including FOB 4, which was located south of Da Nang, nestled between Highway 1 on the west, the South China Sea on the east, and Marble Mountain (which was a series of five mountains of various sizes) to the south. A POW prison, a Special Forces C-Team camp, and other military branches were located to the north.