American helicopter companies, deployed to South Vietnam earlier in the month, flew South Vietnamese troops into combat for the first time in the growing conflict against Viet Cong insurgents. The missions represented a quiet but consequential deepening of US military involvement years before major American ground combat units arrived.
In December 1961, the United States had only a few thousand military advisors in South Vietnam, publicly described as trainers rather than combatants. But newly arrived US Army helicopter units, flying Piasecki H-21 'Flying Banana' transports, gave South Vietnamese forces something they had never had: rapid mobility over the Mekong Delta's flooded rice paddies and canals.
On missions in the days around December 23, American pilots ferried South Vietnamese infantry into positions to strike at Viet Cong units that had previously melted away into terrain government forces could not easily cross. The helicopters proved so effective that Viet Cong forces quickly adapted, developing anti-helicopter tactics that foreshadowed years of guerrilla warfare to come.
Washington insisted American personnel were not engaging in combat, technically flying the missions rather than fighting on the ground, but the distinction blurred quickly as American crews came under fire and occasionally returned it. These early helicopter operations set a pattern of American technological support that expanded steadily over the following decade, eventually growing into the massive air mobility operations that defined the American war in Vietnam.