I don’t know if you have ever noticed this or it never was something that caught your eye. If you look at a lot of photos and footage from WW2 up through Vietnam, you will see the practice shown above. I’m talking about the knife or bayonet directly behind the holster for the sidearm. The idea of having your knife right where you are used to drawing your side arm from is a good idea.
A lot of people have speculated on how this was pulled off. Well. you can see below.