The M9 Bayonet is a multi-purpose knife and bayonet officially adopted in 1984 by the U.S. Army. It has a 7-inch blade and is issued with a sheath designed to double as a wire cutter. The M9 ...

How did the 15 inch sized bayonets of the 17th century evolve by the 21st Century into a combat gadget the size of a pocket knife, that is still in widespread use today with armies across the world?

An electronic or optical connector that is designed similar to the way a bayonet (knife) is mounted onto the end of a rifle. The plug is pushed into the socket and turned to make a tight connection.