This is an Arnold tin clockwork submarine. Manufactured in 1938 for the German market it is obviously a U-Boat. Note the swastika on the conning tower. It is missing its key and guy wires but is otherwise functional. Post war the Arnold company made this same toy but with the swastika swapped for an American white star. This was sold to U.S. servicemen for their children. The Arnold company stopped making boats in 1950.