January 12, 1962
In Operation Chopper, helicopters flown by U.S. Army pilots ferry 1,000 South Vietnamese soldiers to sweep a NLF stronghold near Saigon. It marks America's first combat missions against the Vietcong.

Early 1962
Operation Ranchhand begins. The goal of Ranchhand is to clear vegetation alongside highways, making it more difficult for the Vietcong to conceal themselves for ambushes. As the war continues, the scope of Ranchhand increases. Vast tracts of forest are sprayed with "Agent Orange," an herbicide containing the deadly chemical Dioxin. Guerrilla trails and base areas are exposed, and crops that might feed Vietcong units are destroyed.

April - June 1964
American air power in Southeast Asia is massively reinforced. Two aircraft carriers arrive off the Vietnamese coast prompted by a North Vietnamese offensive in Laos.

August 7, 1964
The U.S. congress passes the Gulf of Tonkin Resolution, giving President Johnson the power to take whatever actions he sees necessary to defend Southeast Asia.

February 13, 1965
President Johnson authorizes Operation Rolling Thunder, a limited but long lasting bombing offensive. Its aim is to force North Vietnam to stop supporting Vietcong guerrillas in the South.

April 3, 1965
An American campaign against North Vietnam's transport system begins. In a month-long offensive, Navy and Air Force planes hit bridges, road and rail junctions, truck parks and supply depots.

April 7, 1965
The U.S. offers North Vietnam economic aid in exchange for peace, but the offer is summarily rejected. Two weeks later, President Johnson raises America's combat strength in Vietnam to more than 60,000 troops. Allied forces from Korea and Australia are added as a sign of international support.

April - May 1966
In Operation Birmingham, more than 5,000 U.S. troops, backed by huge numbers of helicopters and armored vehicles, sweep the area around north of Saigon. There are small scale actions between both armies, but over a three week period, only 100 Vietcong are killed. Most battles are dictated by the Vietcong, who prove elusive.

Late May - June 1966
In late May 1966, the North Vietnamese 324B Division crosses the Demilitarized Zone (DMZ) and encounters a Marine battalion. The NVA holds their ground and the largest battle of the war to date breaks out near Dong Ha. Most of the 3rd Marine Division, some 5,000 men in five battalions, heads north. In Operation Hastings, the Marines backed by South Vietnamese Army troops, the heavy guns of U.S. warships and their artillery and air power drive the NVA back over the DMZ in three weeks.

June 30, 1966
On Route 13, which links Vietnam to the Cambodian border, American forces are brutally assaulted by the Vietcong. Only American air and artillery support prevents a complete disaster.