In his 1943 "State of the Union" Address, President Franklin Delano Roosevelt commented, "in Africa, we are shooting down two enemy planes to every one we lose, and in the Pacific and the Southwest Pacific we are shooting them down four to one."
Studies by Depuy and others have shown that on the ground, one American, British, or Soviet soldier was not the equal of one German soldier. And even with a large superiority in numbers and firepower, Allied forces had difficulty inflicting human casualties on the Germans at a rate much above one to one. The disparity in tank effectiveness was even more skewed in favor of the Germans, as they inflicted tank casualties on the allies at a multiple of their own.
What accounts for the relative U.S. superiority in the air? And is it fair to say that without air superiority, the U.S. and Allies would have had great difficulty beating the Germans? Or are there credible sources or studies that show that the Allies could have won only using overwhelming numbers and firepower on the ground, without superior airpower?