Group 559 was a transportation and logistical unit of the People's Army of Vietnam. Established on 19 May 1959 to move troops, weapons, and materiel from North Vietnam to Vietcong paramilitary units in South Vietnam, the unit created and maintained the Ho Chi Minh Trail, the supply line that helped the North win the Vietnam War. The purpose of these activities was the support of Vietcong in their struggle to topple the southern regime of President Ngo Dinh Diem. This task was made more difficult by the presence of a demilitarized zone (DMZ) on the border separating the two countries, though the North Vietnamese did send some supplies across the DMZ, their major infrastructure went around it. Group 559 developed road lines through Laos and Cambodia that fed into various areas of northern and western South Vietnam. This system of roads became known as the Ho Chi Minh Trail and was used under the supervision of Group 559 to infiltrate weapons, ammunition, and cadres into the South. Subordinate to the Rear Services General Directorate, the troop consisted of two transportation battalions. In 1960, Group 559 is upgraded to division-level, and established the 70th Regiment. In 1961, the 71st Regiment was set up. By 1962, the group had 6,000 troops organized into two regiments equipped with bicycles and a few trucks. Within one year the force level grew to 24,000 troops and six motorized transport battalions plus engineering, anti-aircraft, and security elements. After the commitment of U.S. and allied forces to the Vietnam War in 1965, Group 559 moved a volume of supplies nearly equal to the total volume of the preceding five years. Increasing North Vietnamese involvement, including the introduction of large ground units, in the southern war and U.S. interdiction of PAVN's logistical system at sea sharply increased the group's overland route. On April 3, 1965, Group 559 acquired the corps-level status of a Military Region reporting directly to the Military Affairs Party Committee and the General Staff, with three subordinate commands for the supply corridors through Laos. Preparations for large-scale main force offensives, both during and after the U.S. withdrawal sharply increased logistical requirements. In July 1973 the group, redesignated the Truong Son Command, converted sectoral and way station forces into divisions or regiments and established five additional regiments. By late 1974, forces under its command included Anti-Aircraft Division 377, Infantry Division 968, the 5 regional commands (division-level):