An insurgency, or guerrilla insurgency, is the antithesis of conventional warfare, Whereas regular armies aim to concentrate force to achieve a decision with maximum speed, guerrilla forces disperse and conduct small-scale operations over an indefinite period of time. The strength of this form of warfare is its resilience; its weakness is the inability of small forces to confront regular armies directly.
In Vietnam, the United States faced a guerilla insurgency over many years beginning in 1954. Although, the insurgency could not defeat the U.S. in traditional military terms, the long-term psychological affects on American political and military leaders as well as the public were sufficient to force a U.S. withdrawal and, ultimately, victory for the guerilla fighters.