21st replacement detachment

The 21st Replacement Detachment was a U.S. Army unit tasked with receiving, processing, and assigning incoming personnel to various combat and support units during times of conflict. Most notably active during the Vietnam War, the detachment operated as part of the Army’s broader personnel replacement system, ensuring a steady flow of well-prepared soldiers to sustain operational effectiveness. Stationed primarily at major in-country replacement depots, the 21st Replacement Detachment managed administrative tasks, conducted briefings, and provided orientation for new arrivals. Through its efforts, the unit played a vital behind-the-scenes role in maintaining the strength and readiness of U.S. forces in theater.