Naval construction units, known as Seabees, were active in the Vietnam conflict from the very beginning of the American presence there. As early as 1954, the Amphibious Construction Battalion 1 was creating refugee camps in South Vietnam, and between 1962 and 1965 they built camps for the Fifth Special Forces Group. During that period, they were also engaged in civic action programs, building airstrips, bridges, dams, roads, housing, and schools. Naval Mobile Construction Battalions, each staffed with 24 officers and 738 enlisted men, began arriving at Da Nang in May 1965 as part of the 30th Naval Construction Regiment. The 3rd Naval Construction Brigade arrived in Vietnam on June 1, 1966. The 32nd Naval Construction Regiment was sent to Vietnam on August 1, 1967, to handle construction needs in the Hue-Phu Bai region. The majority of Seabee activities took place in I Corps, where they assembled waterfront facilities, storage areas, ammunition dumps, roads, and bridges. The Seabees were based at Da Nang, Chu Lai, Hue-Phu Bai, Dong Tam, and Quang Tri. At their peak strength in 1968, Seabees totaled more than 10,000 men. The last Seabee unit to leave Vietnam was the 3rd Naval Construction Brigade, which left on November 1, 1971.