[sharpneli]

The thing is that a battleship is huge. You can kill a tank with a modern subcaliber penetrator because a tank is literally an armored box. Penetrate that and the splinters etc will kill anything inside.

Shoot something like it to a battleship and you make a tiny hole and maybe break a laundry machine. Sure with enough shells you could disable it but that requires a ton and more of shells.

To damage a ship you don’t only need to penetrate the armor you also need to deliver substantial amount of explosives inside said armor.

Don’t get me wrong. The fleet would be wiped out. But against a BB puny 4.5” does nothing, except maybe when delivering incendiaries to the superstructure. Modern fire control allows it to absolutely wreck all destroyers and smaller though combined with autoloaders.

EDIT: More importantly in order to even have that reasonable penetration chance with 4.5” gun you need to be within few kilometers. And at that distance the 1918 RN is really dangerous. Ideally stay farther than maybe 20km.