In late 1967, Giap concentrated some 40,000 soldiers in the hills of northwest South Vietnam and orchestrated a series of assaults on a string of American combat bases in the highlands, not far from a Marine base called Khe Sanh, which the North besieged in January 1968. Giap later called these attacks a “diversion” to trick the Americans into moving forces from the populated areas to defensive positions in the hinterland. Most American leaders fell for it; one of the few who didn’t, Adm. U. S. Grant Sharp,