British destroyer gun and torpedo fits for different escort roles

O-class armament varied with the intended balance between surface fighting and air defence. A 4.7-inch fit emphasized surface gunfire, while four high-angle 4-inch guns provided an alternative focused on air defence. The 4-inch arrangement could retain two quadruple torpedo mountings, whereas the surface-gun configuration described here carried one quadruple mounting with an additional 4-inch anti-aircraft gun. Larger destroyers also combined twin gun mountings with substantial torpedo batteries. Most also carried roughly forty to sixty depth charges. Mine rails, or provision for fitting them, allowed many Royal Navy destroyers to take on minelaying duties.