Although gunpowder was introduced into Europe in the 14 century, it had already been in use for many centuries in China. During the 14th and 15 centuries, European nations used gunpowder and metal working techniques to develop larger and larger siege weapons, which came to be called Bombards. Invaders now had a weapon that was capable of smashing down city and castle walls. The largest Bombard was the Russian's Tsar Cannon, which weighed in at almost 40 tons (36,360 kilograms) and had a 36-inch (91-centimter) bore. These large, heavy weapons were very cumbersome to use. Thus, Bombards were only used against large cities, castle walls, and heavy fortifications - all of which became obsolete by the end of the 15th century.
