What did Germany's decision to emphasise submarines convince Britain to do?
Short answerIt reinforced the view that containment was working while also suggesting that the future war might not be decided by a traditional grand fleet battle.
NotesThe answer reads the German submarine turn as confirmation that British pressure had constrained the surface fleet. Britain continued with Renown and Repulse, the Admiral-class battlecruisers, and then the G3 concept. At the same time, German behaviour suggested that a future conflict might not culminate in the expected decisive fleet action. The watch point links enemy adaptation to Britain's continued but evolving capital-ship programme.