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a type of military action using small mobile irregular forces to carry out surprise tactics against hostile regular forces
Spanish 'skirmishing' + warfare
Wars fought with hit-and-run tactics by small groups against an invader or against an established government. (See counterinsurgency.)
type of warfare fought by irregulars in fast-moving, small-scale actions against orthodox military and police forces and, on occasion, against rival insurgent forces, either independently or in conjunction with a larger political-military strategy. The word guerrilla (the diminutive of Spanish guerra, "war") stems from the duke of Wellington's campaigns during the Peninsular War (1808-14), in which Spanish and Portuguese irregulars, or guerrilleros, helped drive the French from the Iberian Peninsula. Over the centuries the practitioners of guerrilla warfare have been called rebels, irregulars, insurgents, partisans, and mercenaries. Frustrated military commanders have consistently damned them as barbarians, savages, terrorists, brigands, outlaws, and bandits.