Essential cruisers, distorted by doctrine

Japanese heavy cruisers proved valuable in many battles and operations beyond their intended Kantai Kessen role, so they were worth building. Assigning essential reconnaissance to them also made aviation facilities dominate layouts, narrow hull choices, and influence unusual gun arrangements. British practice isolated aircraft installations in self-contained structures, while American designs placed them toward the end of the hull and away from other vital spaces. Japan instead had to build the cruiser around exposed aviation equipment because its scouts were central to the fleet's intelligence system. The need to operate aircraft at high speed also favored long, narrow hulls and made compact twin-gun mounts consequential for the rest of the design.