Guerrilla warfare is a form of irregular warfare in which small groups of combatants, typically armed civilians or irregular soldiers, use military tactics such as ambushes, sabotage, raids, and hit-and-run attacks to harass and disrupt a larger, more conventional military force.
The term "guerrilla" originates from the Spanish word "guerra" (war), and specifically refers to the tactics used by Spanish peasants who fought against French forces during the Peninsular War (1808-1814). These peasant fighters, known as guerrilleros, would ambush French troops and then disappear into the surrounding countryside, making it difficult for the French to track and defeat them.
The concept of guerrilla warfare has since spread throughout the world and has been employed in many different conflicts.