You could heat coffee or hot chocolate in them. Canteens are made of plastic. You can't heat anything in them and they always taste like plastic. 1945- Officers were professional soldiers first. They commanded respect.
Officers are politicians first.
They beg not to be given a wedgie. They collected enemy intelligence and analyzed it. They collect our pee and analyze it. If you don't act right, the commander might put you in the stockade till you straighten up. If you don't act right, they start a paper trail that follows you forever.