Norfolk survived several 11-inch hits from Scharnhorst because the shells passed through lightly protected portions of the hull without exploding. The video argues that armour thick enough to resist eight-inch fire can create a different hazard by triggering much larger shells inside the ship. County protection therefore concentrated useful armour where vital systems needed defence while leaving other areas thin. The example turns apparent under-protection into a more complicated design compromise between stopping cruiser shells and limiting the damage from capital-ship hits.
Notable Point · 34:52-36:02
County-class armour and the danger of stopping too much
Norfolk's survival after Scharnhorst's 11-inch hits opens a useful explanation of why cruiser protection cannot simply be made thicker everywhere.