A type of military action using small mobile irregular forces to carry out surprise tactics against hostile regular forces.
Guerilla Warfare was used for the first time in the Madrid Dos de Mayo Uprising (May 2, 1808). This tactic was widely used by the Viet Cong and North Vietnam Army in the Vietnam War. “Guerrilla warfare is the unconventional warfare and combat with which a small group of combatants use mobile tactics (ambushes, raids, etc.) to combat a larger and less mobile formal army. The guerrilla army uses ambush (draw enemy forces to terrain unsuited to them) and mobility (advantage and surprise) in attacking vulnerable targets in enemy territory.” http://en.wikipedia.org/wiki/Guerrilla_warfare
The Vietnamese Communists, or Vietcong, were the military branch of the National Liberation Front (NLF), and were commanded by the Central Office for South Vietnam, which was located near the Cambodian border. For arms, ammunition and special equipment, the Vietcong depended on the Ho Chi Minh trail. Other needs were met inside South Vietnam.
Main force Vietcong units were uniformed, full-time soldiers, and were used to launch large scale offensives over a wide area. Regional forces were also full-time, but operated only within their own districts. When necessary, small regional units would unite for large scale attacks. If enemy pressure became too great, they would break down into smaller units and scatter.
In December 1965, Ho Chi Minh and the North Vietnamese leadership ordered a change in a way the war in the South was to be fought. From now on, the Vietcong would avoid pitched battles with the Americans unless the odds were clearly in their favor. There would be more hit and run attacks and ambushes. To counter the American build-up, Vietcong recruitment would be stepped up and more North Vietnamese Army troops would be infiltrated into South Vietnam. The Vietcong, following the example of Chinese guerillas before them, had always given the highest priority to creating safe base areas. They were training grounds, logistics centers and headquarters. They also offered secure sanctuaries for times when the war might go badly. Hiding the base areas had always been a high priority for the Vietcong. Now, with American spotter planes everywhere, it was more vital than ever to protect them. In remote swamps or forests, there were few problems, but nearer the capital, it was much more difficult. The answer was to build enormous systems of underground tunnels. The orders coming from NLF headquarters were absolutely clear. Tunnels were not to be treated as mere shelters. They were fighting bases capable of providing continuous support for troops. Even if a village was in enemy hands, the NLF beneath were still able to conduct offensive operations. There were complexes big and small scattered across the country. Each villager in a NLF area had to dig three feet of tunnel a day. There was even a standard handbook specifying how tunnels were to be built. The biggest tunnel systems were in the Iron Triangle and the Cu Chi District, only 20 miles from Saigon.