What if the French fleet had been ordered to Scapa Flow before France fell and then served with the Royal Navy?
Short answerThe Allies gain fast battleships and stronger Atlantic and Mediterranean forces, with further advantages if French colonial authorities also choose to keep fighting.
NotesThe Royal Navy gains fast capital ships and a larger pool of destroyers and submarines by bringing the French fleet into the Allied war effort. Unfinished French battleships could go to American yards for completion, while older ships reinforce convoy escorts and the Mediterranean Fleet. Force H could concentrate more consistently on the western Mediterranean because other units would be available for Atlantic operations. French North Africa becomes a further advantage if its army and colonial authorities also choose to continue fighting, although that alignment is an additional condition. Italy would then face pressure from both directions in North Africa and stronger submarine opposition at sea. The short crossing between Sicily and Tunisia would still depend on moving supplies from northern Italy through limited transport infrastructure. A stronger Mediterranean position could free British carriers for operations against Bismarck and for the Far East.