Seydlitz: armour without tactical dominance

Seydlitz carried thicker armour at its strongest points than Queen Mary, but she paired it with 11-inch guns and about 26.5 knots. Even 88,500 shaft horsepower could not close the roughly one-and-a-half-knot speed gap to the British battlecruiser, which also carried 13.5-inch guns. British battleships combined those heavier guns with much thicker protection. That left Seydlitz poorly placed between roles: a modern battleship outgunned and outarmoured her, while a faster battlecruiser could avoid the stand-up engagement where her armour mattered most. Her wing-turret arrangement also limited forward fire during a chase and risked blast damage during cross-deck firing. The usefulness of her thicker armour depended on whether she could force the kind of fight in which it mattered.