An early Vanguard reshapes the Bismarck chase and Force Z

A Vanguard laid down with Duke of York might have finished around the same time as Prince of Wales because its established 15-inch guns required fewer trials. It could then have been available at Scapa Flow when Bismarck sailed, giving the Home Fleet another fast battleship while Hood's machinery was worn. Its effect on Force Z depends on which historical ship it replaces. Replacing Prince of Wales with Vanguard would let the formation use more of Repulse's speed; in the proposed scenario, the Japanese scout would reach their historical position after the ships had moved farther towards Singapore. Replacing Repulse instead would leave the formation limited by Prince of Wales's speed. Vanguard's stronger anti-aircraft armament and torpedo protection would then give it a better chance of surviving the attack, especially with only a finite number of Japanese torpedoes available. That second scenario does not automatically save Prince of Wales, whose stern hit remains potentially fatal unless Vanguard's fire disrupts the attack.