Piorun accompanied Vian's flotilla when it left convoy duty to search for Bismarck. By day she could attack alongside the other destroyers, but at night she acted as a loose safety outside the four Tribals' rehearsed box. One destroyer made real or dummy torpedo runs and gun attacks while the others held their positions; if Bismarck turned to engage the attacker at close range, the others could attack her. This depended on training and reading radar without continuous communication, and Piorun had not yet practiced enough with the group to join safely. A mistaken movement could expose her to friendly torpedoes. Accepting that limit showed respect for the Tribals' professional judgment, in this interpretation. Accounts differ over Bismarck's response to Piorun's signal, "I am a Pole." Piorun later delayed her fuel-related withdrawal by an hour, a decision that Vian appears to have tolerated while she could still get home.
Chapter · 1:05:18-1:11:26
ORP Piorun and the destroyer box around Bismarck
Piorun joined the pursuit of Bismarck but stayed outside the Tribals' rehearsed night box, where coordinated dummy and live attacks kept the battleship under pressure.