4 September – On this day

In South Vietnam the U.S. 1st Marine Division launches Operation SWIFT, a search and destroy operation in I Corps Tactical Zone (the region south of the Demilitarized Zone).

A fierce four-day battle ensued in the Que Son Valley, 25 miles south of Da Nang. During the course of the battle, 114 men of the U.S. 5th Marine Regiment were killed while the North Vietnamese forces suffered 376 casualties.