In 1971, while U.S. ground forces were prohibited from crossing the Laotian border, a South Vietnamese Army corps, with U.S. air support, launched the largest airmobile operation in the history of warfare, Lam Son 719. The objective: to sever the North Vietnamese Army's main logistical artery, the Ho Chi Minh Trail, at its hub, Tchepone in Laos, an operation that, according to General Creighton Abrams, could have been the decisive battle of the war, hastening the withdrawal of U.S. forces and ensuring the survival of South Vietnam. The outcome: defeat of the South Vietnamese Army and heavy losses of U.S. helicopters and aircrews, but a successful preemptive strike that met President Nixon's near-term political objectives.

Johnson's war -- The truck hunters -- Nixon's war -- 1970: the Cambodian incursion -- Planning Lam Son 719 -- Dewy Canyon 2 -- The first week in Laos -- The second week in Laos: the attack stalls -- Collapse on the northern flank -- Onward to Tchepone -- The retreat from Laos -- After Lam Son 719.