A battering ram is a weapon that uses blunt force to destroy or break open a wall, door or fortification. Rams vary in size, depending on historical context. Ancient battering rams were often very large, carried and swung by entire teams of men. This was because of the nature of fortifications at the time - opening a gate or breaking down a wall allowed entry into a town and would often lead to victory. Up until the Renaissance, these rams consisted of huge wooden logs or stakes, usually hung by a series of ropes, allowed to swing back and forth. A team of men would then swing the ram back and forth, using the momentum to break the defense. The advent of cannon and firearms rendered these large rams obsolete, because a cannonball was much more effective. Modern-day rams are often used by police or military forces to break down barriers or doors. These rams are small but heavy, operated by one or two people. Swung against the door, the force breaks it and allows entry.