While the bayonet dates to the 17th century, it has evolved through technological innovations over the years. In 2003, the Marine Corps replaced its standard-issue bayonet with a longer, sharper model, the OKC-3S. The new model, designed by New York's Ontario Knife Co., was also more effective when brandished as a hand knife - not to mention more ergonomically correct. Perhaps more vitally, the blades were also better able to pierce body armor, a concern particular to modern warriors. More than 120,000 bayonets were commissioned to supply one to each Marine, at an estimated price of $36.35 each, or $4.36 million total.
In addition to potential use in hand-to-hand combat, bayonets are said to be useful for keeping prisoners under control and for "poking an enemy to see whether he is dead."
The Marines aren't the only branch of the military that equips its soldiers with bayonets. The Army issues the M9 bayonet knife, which has been in use since the 1980s, but troops have moved away from the detachable knives in recent years. In 2010, the Army began to scale back on bayonet drills in favor of calisthenics, perhaps a wise move given that the soldiers rarely carry bayonets on their rifles, and since the last U.S. bayonet charge was in 1951.
Others, however, have still found uses for the bayonet charge in recent years. Just last month, a British soldier was honored for a bayonet charge on the Taliban that he led in 2011. This charge was reminiscent of another British bayonet charge, in Basra, Iraq, in 2004. In 2011, Col. Moammar Gadhafi was reportedly killed by a bayonet stab to the rear.
While the use of bayonets is rare, the use of horses is even rarer. The military still maintains the historic First Cavalry Division out of Fort Hood, Texas, and the division's horse detachment still sometimes mounts up for the occasional charge. But these charges tend to take place only as part of parades, historical ceremonies, and fairs.
Forrest Wickman writes for Slate.