A 6-inch-gunned submarine could overwhelm many escorts that navies still considered sufficient against the historical undersea threat. Britain already had an evolutionary starting point in the roughly 1,000-ton Shoreham-class sloops of the early 1930s. Their two 4-inch guns, minesweeping and minelaying fittings, gunboat utility, ASDIC, and depth charges made them flexible imperial patrol ships. The counterfactual threat turns that modest peacetime program into the beginning of a much larger purpose-built anti-submarine force.
Chapter · 35:41-37:00
Cruiser submarines accelerate British ASW construction
Gun-armed cruiser submarines make old destroyers and First World War sloops look inadequate, accelerating investment in modern British ASW ships.