Choosing between four-, five-, and six-inch secondaries

How should designers weigh four-, five-, and six-inch secondary batteries?

The choice balances rapid engagement, shell effect, mounting availability, expected targets, and whether a navy can afford specialised weapons.

A lighter gun can enter action quickly, while a six-inch weapon does more damage. Four-inch guns suit light threats, and six-inch weapons are more useful against larger or more survivable surface targets. Navies with enough ships and a home-water focus can afford specialised armaments instead of demanding one universal calibre. British practice separated lighter weapons from heavier surface targets, while American ships also used different five-inch types for surface and anti-aircraft work.