Range, speed, and armor in a battlecruiser duel

The battlecruiser stays near the edge of its 21-kilometre gun range and holds 25 knots, the preferred speed for accuracy. The opponent reaches about 20 kilometres and makes roughly 22 to 23 knots, leaving only a small margin in range and speed. Closing would bring the thinner ship within a battleship's effective reach: the French vessel has 17.4 inches of armour against roughly 12 inches on the battlecruiser, a proportion described as historically plausible. Mobility works here by preserving separation, and the small speed advantage cannot erase the large protection disadvantage.