Carrier submarines compete with patrol range and regional specialization

I-400-like boats can develop without World War II, but their aircraft are effectively expendable because recovering them exposes the submarine on the surface. The concept resembles an early guided-missile submarine: a long-range boat that delivers a strategic payload rather than a conventional patrol aircraft. Lessons from the Spanish Civil War instead emphasize how long submarines can remain on station and how far they can travel, encouraging larger ocean boats. The Royal Navy may retain small, medium, and large types because the North Sea, Mediterranean, Atlantic, Indian Ocean, and Pacific impose different requirements. Spectacular special-purpose designs therefore compete with the geostrategic logic behind a balanced submarine force.