In any case, the bayonet isn't as important as it used to be. It's more usual now to go into the attack with hand-grenades and your entrenching tool. The sharpened spade is a lighter and more versatile weapon - not only can you get a man under the chin, but more to the point, you can strike a blow with a lot more force behind it. That's especially true if you can bring it down diagonally between the neck and the shoulder, because then you can split down as far as the chest. When you put a bayonet in, it can stick, and you have to give the other man a hefty kick in the guts to get it out.