A land mine, according to a war department field manual, is an encased charge of explosive fitted with one or more detonating devices designed to be activated by vehicles or personnel. There are two common types: antitank and antipersonnel. Antipersonnel mines produce casualties to personnel on foot and are ineffective against armored vehicles. Used to protect other mines or obstacles, to enhance local security, or to harass and delay enemy troops, they have an explosive charge anywhere from one-quarter of a pound to four pounds. Mines and standard booby traps are fitted with one or more safety devices, usually a pin. To disarm one, a man locates the hole from which the pin has been withdrawn. A mine field consists of several mine belts, which are designed to break up and canalize an enemy’s attack formation and restrict his movements to areas covered by defensive fires, particularly those of antitank and automatic weapons.