I've lost the reference for a quote.  I believe it was from a British official
between WWI and WWII, to the effect that "Air power, oil, and shipping form the
basis of national power.  The oil powers the planes and the ships.  The ships
transport the oil and the planes.  And the planes protect the oil and the ships.
Britain is the greatest power precisely because it has the most of all three."

I wonder if it was Churchill.  He did propose that all British ships
run on oil, and was First Lord of the Admiralty for a time.