On this date the United States began Operation Rolling Thunder, a sustained bombing campaign against North Vietnam. Although not a ground operation, it signaled a major U.S. escalation and helped set conditions for the rapid introduction and expansion of American ground combat forces in South Vietnam.
About 3,500 U.S. Marines landed at Da Nang to protect a key air base. Their arrival marked the start of sustained U.S. ground combat involvement and the beginning of a fast troop buildup that would reshape the war in South Vietnam.
U.S. Marines carried out Operation Starlite near Van Tuong as a combined air, ground, and amphibious assault against Viet Cong forces threatening the Chu Lai area. It is widely described as the first major offensive action conducted by a purely U.S. unit, setting a pattern for later large “search and destroy” operations.
U.S. Army and North Vietnamese forces fought the Battle of Ia Drang in the Central Highlands. The battle highlighted the power of helicopters and air support, but it also showed that U.S. units could face well-organized North Vietnamese regular forces, not only guerrillas.
Operation Masher/White Wing brought U.S. and allied forces into major fighting in Bình Định Province. It was described as the largest search-and-destroy mission up to that point, reflecting how U.S. strategy had shifted toward sweeping operations meant to find and fix enemy main forces.
In Operation Hastings, U.S. Marines and allied forces fought near the Vietnamese Demilitarized Zone (DMZ). The operation reflected growing concern about North Vietnamese units crossing or operating near the DMZ area and helped drive further U.S. focus on border-region battles.
Operation Attleboro began as sweeps around Tay Ninh and grew into a large, multi-division fight in War Zone C. It showed how quickly small probes could escalate into major engagements when U.S. units encountered organized enemy forces and large supply areas.
During Operation Cedar Falls, U.S. forces conducted a major operation in the Iron Triangle area northwest of Saigon. The goal was to disrupt Viet Cong control, uncover base areas, and deny the area’s use; it also involved large-scale civilian displacement, illustrating the human impact of this operational approach.
Operation Junction City ran for months and was one of the largest U.S.-led operations of the war, focused again on War Zone C near the Cambodian border. It aimed to damage Viet Cong/North Vietnamese forces and their infrastructure, demonstrating the scale U.S. ground operations had reached by 1967.
The Battle of Dak To in the Central Highlands involved prolonged combat in rugged terrain near the border. It reflected an attrition-style struggle in which U.S. units sought to engage enemy main forces, while North Vietnamese units used difficult terrain and prepared positions to impose heavy costs.
In late January 1968, North Vietnamese and Viet Cong forces launched coordinated attacks across South Vietnam during the Tet holiday period. Although many attacks were eventually repelled, the scale and surprise of Tet strongly affected U.S. perceptions of the war and intensified debate over strategy and costs.
U.S. Army soldiers killed large numbers of unarmed Vietnamese civilians at Sơn Mỹ (My Lai). When the massacre later became public, it fueled outrage and deepened mistrust of official claims about U.S. operations, becoming a lasting symbol of moral and operational breakdown in the ground war.
Operation Dewey Canyon was a major U.S. Marine sweep in the A Shau Valley region. It is often described as the last major offensive by the 3rd Marine Division, reflecting how U.S. ground operations were beginning to shift from peak escalation toward changing roles and eventual drawdown.
U.S. forces in Vietnam reached their highest level in April 1969 (about 543,000), marking the peak of the buildup phase. The peak underscored both the scale of the U.S. ground commitment and the growing challenge of sustaining a large war amid rising costs and public controversy.
U.S. and ARVN forces fought a costly battle for Hill 937 (“Hamburger Hill”) in May 1969 during Operation Apache Snow. The intense fighting and the decision to later abandon the position made the battle a major controversy, helping accelerate pressures to reduce high-casualty U.S. ground offensives.
In mid-1969, President Richard Nixon announced an initial withdrawal of 25,000 U.S. troops, to be completed by the end of August. This decision signaled a clear shift away from the 1965–1969 buildup toward a new phase in which U.S. ground forces would gradually shrink and more responsibility would shift to South Vietnamese forces.
U.S. ground troop buildup and major operations in Vietnam (1965–1969)