The Royal Navy's costliest Second World War mistakes

What was the Royal Navy's biggest blunder during the Second World War?

Clarke selects Courageous and Glorious for their long-term cost; other panelists argue for Royal Oak or the avoidable cruiser losses off Crete.

One answer chooses the losses of Courageous and Glorious because two additional carriers could have materially strengthened the fleet in 1941, possibly including Force Z. Other panelists argue for Royal Oak, where known defenses at Scapa Flow remained incomplete, and for the decision to send ammunition-depleted cruisers back into the Crete evacuation, losing Fiji and Gloucester. The cases measure different kinds of failure: long-term strategic cost, preventable security weakness, and a dangerous mismatch between orders and ship condition. The Crete example also exposes a service culture whose determination to support the Army could override operational limits.