In Normandy, however, the US Army was transformed into an entirely different sort of animal... The Wehrmacht always prided itself on its superior prowess in maneuver and its dominance in fluid operations, but in Normandy they were surpassed, humiliated, and destroyed in a campaign which launched the United States into its era of military supremacy and unparalleled swagger.

We can broadly think of America’s operational conduct of the war against Germany as occurring in two distinct phases. The first phase, essentially comprising the campaign in North Africa and the early encounters in Italy, revolved around learning how to contend with the German panzer package...

In the second phase, the US Army emerged as a first class combined arms force in its own right, capable of moving like lightening when it wanted to.

At the outbreak of war, the USA was responsible for over half of the world’s oil production. As a result, American was a highly motorized society, with mass adoption of the private car and commercial trucking, and a correspondingly titanic automobile industry.

The upshot of all this was that uniquely among all the belligerent parties, the United States found it almost trivially easy to motorize its ground forces - churning out trucks, halftracks, recovery vehicles, and jeeps by the tens of thousands.