Art and practice of concealment and visual deception in war. Its goal is to prevent enemy observation of installations, personnel, equipment, and activities. Camouflage came into wide use in World War I in response to air warfare. Aerial reconnaissance (and later aerial bombardment) required concealment of troops and equipment. By World War II, long-range bombing threatened warring countries in their entirety, and almost everything of military significance was hidden to some degree, using mottled, dull-coloured paint patterns (green, gray, or brown), cloth garnishing, netting, and natural foliage. Dummies and decoys, including fake vehicles and airfields, tricked enemy planes into bombing harmless targets. It remained an important technique after World War II, used with notable success by communist guerrilla units in the Vietnam War.