Tanks developed out the experiences of World War I, whereby the internal combustion engine was combined with steel armor plate, caterpillar tracks, cannons, and machine guns to produce a vehicle that could defeat the stalemate of trench warfare. Military doctrine in the interwar period was dominated by the possibility of using masses of armored vehicles on the battlefield. The original idea was that tanks would operate on a broad front with infantry, using their cannons and machine guns to knock out enemy positions.