By 1914, copper had become an essential component of every weapon, vehicle, and piece of equipment used on the battlefield. Its ability to conduct electricity, withstand water, and transmit heat made it ideal for many different applications, as did its malleability and durability. Engineers used copper to improve weapons and develop machines that were far more deadly than those used in previous conflicts, including armored tanks and airplanes. Submarines had increased capacity and range; rifles and machine guns were more accurate than ever before