Had Vian's force not been pulled into convoy duty after the Norway losses, it likely would have accompanied Hood. The magazine hit could still have occurred. An aggressive torpedo attack would then have forced Bismarck and Prinz Eugen to split attention among Hood, Prince of Wales, cruisers, and the destroyers. Even limited torpedo damage could have ended Bismarck's freedom to operate, so the counterfactual concerns force composition rather than a certain British victory.
Notable Point · 29:42-33:29
What destroyers might have changed at Denmark Strait
A bounded counterfactual asks how five fuelled, torpedo-armed destroyers might have divided German fire and constrained Bismarck after Hood's loss.