During the late 1950s and early 1960s, US Army planners sought to increase the Army's helicopter force. The Army developed new tactical doctrine using helicopters; the airmobile concept, which was based largely on air cavalry units. Such units were descendants of the US Cavalry, which had operated as light, horse-mounted infantry. Air Cavalry troopers were, in essence, horse soldiers, and helicopters were their steeds. True to their proud and colorful...