X1 and the case for a cruiser submarine

X1 was conceived partly as an experiment for understanding and countering an enemy submarine commerce raider and partly for possible operations against Japanese trade. An Anglo-American war presented a different problem: British bases and control of Atlantic approaches made a conventional blockade more plausible than distant submarine commerce raiding. Its twin 5.2-inch mountings promised many more attacks on merchant ships than a limited torpedo outfit could provide. In practice the ammunition hoists rarely achieved their intended rate, machinery was troublesome, accommodation was cramped, and ventilation and humidity were poor. The design combined strategic range and impressive gun size with the practical weakness of asking a submarine to conduct prolonged surface combat.