Destroyer refits expose national gun-layout differences

Newly available twin turrets raise the destroyer's battery from three to six five-inch guns. The campaign has 293 destroyers, so even a straightforward design change becomes a large modernization programme. The gun arrangement resembles German or American practice more than a characteristically British layout. The final order places 94 destroyers and seven cruisers in refit, an expensive commitment that the campaign economy can still support.