That is well worth a read, tho it is a start-not the end of the point the author is making. One of the persons posting a comment on that site asked about a similar study of the US naval contribution, the same would apply to the air power contribution. If a USAAF aircraft Wing is the equivalent of a ground combat division in firepower and logistics draw then the equation or balance changes noticeably, the US had considerable air forces in combat from mid 1942.
One of the questions I did not see asked or answered in that essay is where the balance of the eight million US soldiers in uniform to 1944 were. In terms of ground combat and ground service they were not doing much more than training in the US, A few others were idle in Iceland (5th Infantry Div) or the UK (29th Inf). But the balance, over fifty divisions spent 1943 in North America either training, or splitting off cadres for the last of the new divisions. Nearly half the ground combat forces the US formed had completed their first training cycle by early 1942, those which did move overseas completed a second training cycle at or before the end of 1943. Some actually went through a third before they entered combat in 1944. Part of the training was necessitated by large scale removal of cadres for new units, part from removal of trained men for casualty replacements, and part because of the extensive reorganization of the ground combat units in 1941-42. The change from the square to triangular division required recycling through training for several months to asorb the changes in material and doctrine.
In any case there were in any particular month between 25 & 35 divisions in the US that had completed or were near completion of their first or second training cycle. Also a dozen plus independant infantry regiments that had been split from the square divisions & not assigned to a new infantry division. The usual first claim for these not being sent into combat was the problem with Allied cargo shipping. There were serious problems with allocating cargo ships, and a real shortage of ships vs needs, but there was also the factor of questionable allocations. MacArthurs South Pacific offensives of 1943 placed requirement for cargo ships that had been entirely absent from planning in 1942. The reduction of the Bolero operation in 1943 only partially offset that. Neither was the extended campaign in Italy from October 1943 anticipated, and the necessity to provide the south italian population with grain and coal for the winter of 1943 anticipated. There is still some evidence that had Marshal been willing several more US corps could have been sent to the Mediterranean. There is also some suspicion he & his supporters simply did not do so in order to preserve that for what he regarded as the only campaign of decisive value against Germany.
Regardless of accusations made to Marshals decisions the fact remains that there were a large number of trained US ground combat units available for use in Europe in 1943.
