Logistics has been a strength of the US since WWII. There are very few armies in the world prepared to Go Someplace and Do Something. Most can't sustain big units far from their home base for very long. The US does that routinely.

D-Day was postponed to 1945 to allow accumulating enough resources to overcome any opposition. The fiascoes of the Dieppe raid and Dunkirk made it clear this was necessary. In a way, those disasters helped. Otherwise, there would probably have been a failed invasion in 1944.

Eisenhower was a logistics officer by training and background. Which is exactly what was needed. He insisted on having solutions to all the potential logistics problems before attempting the invasion. These included some exotic schemes, such as prefabricated temporary ports and a temporary fuel pipeline across the English Channel, both of which were built and used. It included much special equipment, such as "flail tanks" that could thrash a minefield and get across a hostile beach. More than that, the backup was in place to sustain the follow-up behind the invasion. Very thorough backup, all the way down to prefabricated Coca-Cola bottling plants.