Franklin Roosevelt was a great war-leader in many respects. One of them is that he had developed a politically and technologically sophisticated understanding of what wins wars and during World War II he was not afraid to tell the US Army to back off to get his way. The US Army, looking at war from its single service perspective, started lobbying for a gargantuan expansion as soon as the Japanese attacked Pearl Harbor. The size of the force they wanted was immense. In early 1942, George Marshall asked for the Army to be raised to 212 divisions—a massive force that would have required so much manpower it would have weakened the other services and deprived the USA of much of its industrial workforce.
FDR, however, eventually put Marshall firmly in his place. Though Marshall nurtured his big army ideas for the next year and a half, Roosevelt ended up telling him to construct something very different. Roosevelt wanted to preserve much of America’s industrial workforce, saw a large army as a vehicle for mass casualties as much as anything else, and prioritized air and sea power in the defeat of Germany and Japan. In the end, the Army was kept to a level more than half below what George Marshall wanted—the famous 90-division gamble.
The result was that the US fought a machine intensive, infantry light war, which crushed the life out of the Axis at a historically small number of American casualties—approximately 400,000 deaths in all theatres and all services. It was a number that represented less than 5 percent of the combined military deaths of the Germans and Japanese, and probably less than 2 percent of Soviet deaths.
Fighting wars with machines and fewer soldiers is both strategically and politically (and ethically) a far more effective method than packing out a front line with soldiers. Its also another example of why the western analytic community and US government fails constantly in understanding the best way to fight wars.