This is the largest battleship Keystone produced at 21″. It combines two of Keystone ships into one. However, none of the other battleships look quite like this one. This one has the box. The box itself is not particularly valuable but is extremely rare as most wartime boxes were recycled for the war effort. Interestingly, and not surprisingly, this is the only Keystone toy that I purchased from the original owner. Production was from 1941 to 1942.
From my private collection.