My Flemisch grandad was in the second WW. Back then all official things in Belgium were in French. Can you imagine a Flemisch farmer getting French instructions? Must have been real chaos I suppose.
So many nationalities served in so many armies with officers that didn't speak their own language (think of the USSR, the Italian colonies, the French colonies, the British colonies, the French enlisted in the RAF in WW2...). It isn't so hard to understand military orders when you're doing it on a daily basis.
