A ship's armour thickness reveals the range at which designers expected it to fight. At that intended range, the belt might stop the first comparable shell, though another hit on the same area could penetrate. Internal subdivision and organisation then determined whether the ship survived the resulting damage. Armour schemes therefore express a tactical calculation among gun power, range, and acceptable risk.
Notable Point · 9:22-11:49
Armour as a clue to battle range
A dreadnought was not invulnerable; its armour was designed to resist an initial equivalent-gun hit around an intended engagement range.