Operation Ranch Hand was a part of the Vietnam War, lasting from 1962 until 1971.
It involved 18 million gallons (68,000 m³) of defoliate being dropped on South Vietnam in an attempt to destroy Viet Cong hiding places. The defoliate of choice, which contained dioxin, was an herbicide better known as Agent Orange.
RanchHand crews developed special tactics to avoid ground fire, a constant threat since they had to fly slowly and close to the ground for these missions.
RanchHand pilots flew missions in formations of two or three ships in the early days and as many as 10 in the latter stages of the program.
RanchHand crews were sent to Vietnam on temporary duty, and this became the preferred practice for years.