Surface raiders forced Britain to reserve heavy ships and plan for more than one kind of attack on its convoys. As German surface activity declined, most convoy forces outside the Arctic routes could concentrate on U-boats above all else. That simplification also released Royal Navy ships for the Mediterranean and the Far East. A Type XXI might be more dangerous than an earlier submarine individually, but technical quality could not restore the strategic burden imposed by a fleet able to threaten convoys from several directions.
Chapter · 11:40-14:10
A submarine-only Kriegsmarine simplified Allied defence
Even an advanced Type XXI force would become easier to counter if Germany abandoned the surface-raider threat and let Allied escorts specialize against submarines.