Shells fired at extreme range descend steeply toward the target. They are therefore more likely to strike the deck, turret roof, or upper structure than the side belt. A thick belt does not describe a battleship's protection at every fighting distance. Engagement range determines which parts of the armour scheme receive the greatest test.
Notable Point · 5:45-6:19
Why long-range fire tests deck armour
At extreme range, steeply descending shells make deck and turret-roof protection more relevant than the main belt.