Bayonet is a dagger or knife that fits on the barrel of a gun. Soldiers use the bayonet in hand-to-hand fighting. The first bayonet appeared about 1640 and was probably a French invention. Early bayonets were short spears fitted to a plug that was inserted into the gun barrel. The name bayonet comes from Bayonne, France. Today’s bayonets are fastened to one side of the barrel. But the usefulness of bayonets has become limited with the development of automatic weapons.