The rise in the use of semi-automatic and automatic firearms in the late 19th and early 20th century led to the demise of horse-mounted cavalry. It was only with the development of tanks, armored mobile attack vehicles equipped with high caliber guns, that a weapon was found which could once more be used to punch a hole through enemy field forces. Tanks were invented in World War I for use as armor-shielded assault vehicles that could cross the muddy, uneven terrain of the trench battle zone. Tanks first played a decisive role in World War I in the Battle of Cambrai (Nov. 20, 1917), when 474 British tanks broke through the German lines. The Allies in that war henceforth used tanks in increasing numbers. A tank is usually armed with a cannon mounted in a revolving turret and also has lighter automatic weapons. Tanks are the principal ground-assault weapon in modern mechanized warfare.