Rapid fire, radar, and enough escorts counter E-boats

Schnellboote were dangerous, but they were not a revolution because navies had already confronted fast torpedo craft and developed the torpedo-boat destroyer in response. Motor gun boats renewed that counter with rapid-firing weapons suited to lightly protected targets. Radar gave crews the decisive opportunity to find an opponent first, but they still had to close to very short range and shoot accurately in darkness. Mines, aircraft, and E-boats together accounted for forty percent of British shipping losses in coastal waters, especially early in the war. Doctrine and tactics only became consistently effective when Britain built enough escorts to maintain patrols across the much larger defensive burden created by the fall of France and Norway.