Surprisingly the Third Reich's film studios produced fewer than twenty pictures that dealt directly with combat during World War 2. Five war films were issued in 1941. The finest of them, U-Boote westwärts, was directed by Günther Rittau, one of cinema's most celebrated cinematographers, who shot four of the greatest motion pictures ever made: Siegfried, Kriemhild's Revenge, Metropolis, and The Blue Angel. It was shot on location in and near Kiel, one of Germany's largest naval ports. It used real U-boats, and its cast featured many real U-boat crewmen, which gave the picture much of its authenticity. The film set two cinematic firsts. It was the first feature film to be shot inside a real U-boat, which necessitated the construction of special cameras; and it was also the first picture to mount a camera on the outside of a U-boat so as to capture the dramatic vantage points of diving and rising.