Vertical dive attacks and interwar destroyer AA lessons

How well were warships protected against aircraft diving almost vertically onto them?

Many guns could elevate to roughly 85 degrees, but interwar exercises understated the danger to destroyers and delayed adoption of better high-angle weapons.

Many naval guns could elevate to about 85 degrees, while some mounts reached 87 degrees and smaller weapons could approach a full 90 degrees. Guns positioned away from the centerline or toward the ends of a ship could sometimes engage an aircraft diving toward another part of the hull. Interwar exercises created a separate problem because pilots faced little danger and preferred prestigious capital-ship targets. Their apparent avoidance of destroyers encouraged requirements for lower-angle guns. Former carrier commanders challenged that conclusion, with the Royal Navy's change dated here to about 1935 and some other navies following in 1936-37. Henderson had recognized the problem earlier but could not secure the mounts in time for designs such as the Tribal class. In a hypothetical war delayed until 1942, higher-angle 4.5-inch guns replacing 4.7-inch weapons could have improved British destroyer defence, although aircraft would also have become more capable.