Rate of fire against destroyers and torpedo boats

A destroyer can deliver a disproportionately dangerous torpedo attack while remaining hard to hit with a few large-calibre shots. Its small silhouette, speed, and ability to hide among waves reduce the chance that occasional heavy shells will connect before it launches. Multiple four-inch barrels instead put enough shells into the target area for a few hits to disable an unarmoured attacker. Triple mounts worked well against surface targets, but dual-purpose work demanded the elevation and tracking needed for aircraft. The move to twin 4.7-, 5.5-, and 5.25-inch arrangements sought useful surface fire and an anti-aircraft capability in the same mounting.