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Rail

Source: TW

Dunkirk evac wouldn’t have been possible without rail.
Bulk of freight & troop movement in US was rail.
Rail was so imp in USSR that Stalin created special medals for rail workers.
Even today rail is very imp for Rus military efforts, the Russian military maintain what are called Railway troops who specialize in building, restoring, & operating rail during war.

In WW2 US produced 6 of 7 billion barrels of oil consumed by allies & had domestic oil production 700 times Japan’s.
Last I checked almost all light & heavy road vehicles run on diesel or gas while trains can run on coal or electricity.