Addu became a wartime fallback

Why was Addu Atoll developed when the Eastern Fleet arrived?

It provided a fallback source of fuel and stores after Singapore was lost and in case Ceylon came under attack.

Addu's value did not end when the original rapid-reinforcement plan failed. The Royal Navy needed a second supply point in case Ceylon or other established bases came under attack. Work at the atoll was already under way while the Eastern Fleet was forming and Singapore was expected to hold. Its later use shows how a preselected logistics site could be repurposed when the strategic geography changed.