If you have unknown troops in front of you and you want to find out who they are, fire a few rounds in their direction.
If you are met with precision machine gun fire, they’re German.
If you are met by a volley of precision rifle fire, they are British.
If they surrender, they’re Italian.
If there is a mass wave of infantry and tanks, they’re Russian.
If there is a bayonet and sword charge, they’re Japanese.
If everything is quiet for a minute or two, and suddenly you are in the middle of a massive artillery barrage and air strikes, they are American.