The largest sustained operation inside the Demilitarized Zone (DMZ) opens when U.S. and South Vietnamese infantry and armored troops, supported by planes, artillery, and U.S. Navy ships, move two miles into the buffer zone to relieve enemy pressure on Allied bases along the 40-mile stretch of South Vietnam's northern frontier.
The operation was also meant to prevent an anticipated offensive by two North Vietnamese divisions thought to be currently operating within the DMZ. On September 17, an additional 2,000 U.S. Marines were airlifted into the area and B-52 bombers, striking for the first time in a month, hit targets on both sides of the Ben Hai River, part of the demarcation between North and South Vietnam. Ten days later, an additional 4,000 U.S. Marines attacked into the buffer zone in a coordinated pincer movement designed to trap remaining communist forces. The operation achieved the desired objectives and resulted in 742 North Vietnamese killed; U.S. losses were 65 killed and 77 wounded.