Why disabling the Normandie Dock mattered

The dock affected force allocation because a German capital ship based on France's Atlantic coast could threaten Biscay and mid-Atlantic routes. That possibility would draw British battleships away from Arctic convoys, Mediterranean operations, or Far Eastern duties even while the German ship remained in port. Because the raider chooses when to sortie, the defender may need several heavy ships in an area to ensure that one suitable counter is ready. Destroying the only dock capable of servicing such a ship therefore changes strategy by denying Germany an Atlantic repair base and releasing scarce British strength for other theaters.