How a submarine-only German fleet would change British deployments

A hypothetical German fleet built entirely around submarines is used to explain the effect of having several different naval capabilities. In the counterfactual, Germany could not undertake the Norwegian operation as described, and Britain could concentrate its Atlantic response on anti-submarine warfare. Sloops and Flower-class corvettes would receive that emphasis while larger surface ships could shift toward the Mediterranean against Italy. Fleet-carrier anti-submarine patrols provide a related caution: early British use is described as contrary to the intended doctrine, undertaken because too few other carriers were available, and followed by a carrier loss. The example returns to the distinction between a single problem an opponent can concentrate on solving and several capabilities that impose competing demands.