Bismarck's use of 15-inch shells against the destroyers shows that their attacks were more than a minor nuisance. Cossack's operators could see shell patterns on radar, while the flotilla answered with torpedoes, 4.7-inch fire, and star shell. At intervals the four Tribals broadcast their positions like radio beacons so Admiral Tovey could home his battleships on the moving formation. Bismarck could keep sailing, but she could neither shake the cordon nor stop its radio reports from leading the final battle force toward her.
Notable Point · 23:34-25:51
How Vian's destroyers turned the chase into a moving cordon
Heavy gunfire, radar awareness, illumination, and deliberate radio position reports kept Bismarck boxed in while guiding Tovey's battleships to the target.