Derfflinger and the design triangle

Germany sacrificed some potential battlecruiser speed to obtain protection for supporting its battle line and attempting a North Sea breakout. Derfflinger replaced the preceding ten 11-inch guns with eight 12-inch guns, removing a turret and reducing the number of shells in each broadside. The larger calibre is judged insufficient to compensate fully for that reduction. Stronger protection and a more survivable arrangement came with a 26.5-knot limit, making the design an approach toward the fast battleship from the battlecruiser side. Independently cruising battlecruisers were also more likely than battleships to meet a counterpart alone, making protection against rival battlecruisers increasingly relevant. Germany consequently faced pressure from faster British battlecruisers and from Queen Elizabeth-class battleships whose speed left little room to escape.