Reliable early-war weapons can compound across a campaign

What changes if the early American wartime torpedoes work properly from the start?

They score more early kills, and removing scarce ships sooner can compound into different fleet availability and operational choices later in the war.

Functioning American Mark 13, 14, 15, and 18 torpedoes would have produced more successful early attacks. Navies fight much of a war with the ships and weapons already available at the start because new construction often only replaces losses. Early success against a capital ship can therefore change several later deployments rather than merely adding one vessel to a loss table. The compounding logic is illustrated through British carrier availability, Taranto, Cape Matapan, the Mediterranean balance, and the possibility that different ships might then have been available against Bismarck.