The Royal Navy could protect a critical convoy from Scharnhorst and Gneisenau with one older battleship while holding a stronger reaction group nearby. Adding Bismarck would have changed the arithmetic: escorts and hunting groups would need more capital ships, potentially delaying convoys altogether. The German choice to sortie in ones and twos therefore reduced the strategic pressure their fleet could exert. Concentration mattered less as a promise of immediate battle than as a way to strip escorts from the convoy system.
Chapter · 45:29-56:28
Capital-ship concentration changes the convoy problem
Two German battleships could be deterred by one old British battleship, while three or four concentrated raiders would have forced a far more disruptive response.