KM is short for Kriegsmarine, and IDs a ship as a German naval vessel in the same way HMS, USS, and the like do. Why remove it?
(see Battleship/Talk (I think))
Re MtG: I don't know anything about whether there are national championships outside the U.S.
I do know that the original author did mentioned the (presumed U.S.) national championship. I do not believe this was because the author thought the U.S. was "more worth metioning than other countires", but rather because the author was not well-informed about championships in other countries. If there are indeed national championships in other countries, they should be mentioned, either individually or collectively. Actually, it is quite possible that the original text may have been intended as a collective reference to national championships in many countries. It was your assumption that it was a reference to a U.S. championship which I followed in adding the clarification. - Hank Ramsey
(See Hank Ramsey/Talk)