Why the fall of Singapore was a combined-operations blunder

Was the fall of Singapore in early 1942 an epic naval blunder?

It belongs under combined operations because the army, navy, and wider command structure all contributed to the epic blunder.

The fall of Singapore was an epic blunder spanning several services. The army, navy, and wider command problem make combined operations the better category. That distinction shifts the question from which service failed to how Britain organized the defense across services. This brief answer does not assign responsibility more finely.