Hyde Parker's recall signal at Copenhagen was framed to protect Nelson if he needed to withdraw. Nelson could disregard it if he remained able and willing to continue the attack, while a retreat under the signal would not carry the same blame. Captain Edward Riou in HMS Amazon withdrew because he said he could not see Nelson's contrary signal, whereas the rest of the attacking force pressed on. The episode shows a Royal Navy accepting the risks of fighting a mixed fleet and shore defences while leaving room for judgment at the point of action.
Chapter · 1:36:08-1:38:38
Copenhagen: when a recall signal protected initiative
Hyde Parker's recall signal offered Nelson a blameless exit if the attack was failing without forcing him to abandon a battle he believed he could win.