SMS Derfflinger as she was when she surrendered in 1918. SMS Derfflinger was a battlecruiser of the German Kaiserliche Marine (Imperial Navy) built in the early 1910s during the Anglo-German naval arms race. Derfflinger was completed shortly after the outbreak of World War I in 1914; after entering service, she joined the other German battlecruisers in I Scouting Group of the High Seas Fleet, where she served for the duration of the conflict. The fleet conducted one final operation in April 1918 in an unsuccessful attempt to intercept a British convoy to Norway.