An improved Warrior as a doctrine of overmatch

Which Royal Navy construction decision from the past would be worth changing?

Build four larger, two-deck Warriors to establish overwhelming superiority as the standard for later Royal Navy designs.

The proposed intervention is to choose the larger two-deck version of Warrior and order four ships rather than two. Its immediate purpose would be overwhelming superiority over Gloire. That success is imagined as a precedent for more ambitious Dreadnought and Queen Elizabeth designs. Warrior's seagoing speed would also make a poor match for Monitor's specialized inshore role, with Monitor expected to struggle even to reach an open-ocean engagement. A separate counterfactual judgment is that Virginia might have cracked Monitor's armour if supplied with solid shot.