Royal Navy exercises had normally assigned anti-submarine carrier work to Hermes, Argus, and sometimes Eagle or Furious. At the start of the war, Ark Royal and Courageous were instead sent on those patrols despite being full fleet carriers. That choice departed from developed doctrine, and Ark Royal could have been hit instead. Courageous's loss shows how using scarce fleet carriers in a role intended for less valuable ships turned a known risk into a strategic loss.
Notable Point · 2:17-3:10
Courageous showed the cost of ignoring carrier ASW doctrine
British exercises had used older or smaller carriers for anti-submarine work, but the wartime decision to send Ark Royal and Courageous exposed fleet carriers in a role doctrine warned against.