SMS Derfflinger was a battlecruiser of the German Kaiserliche Marine (Imperial Navy) built in the early 1910s during the Anglo-German naval arms race. She was the lead ship of her class of three ships; her sister ships were Lützow and Hindenburg. The Derfflinger-class battlecruisers were larger and featured significant improvements over the previous German battlecruisers, carrying larger guns in a more efficient superfiring arrangement. Derfflinger was armed with a main battery of eight 30.5 cm (12 in) guns, compared to the 28 cm (11 in) guns of earlier battlecruisers. She had a top speed of 26.5 knots (49.1 km/h; 30.5 mph) and carried heavy protection, including a 30-centimeter (11.8 in) thick armored belt.