Replies

The main reason we were against Germany is because we were aligned with Britain and the treaty they had with Japan.

. . . and you can throw in the fact that Hitler declared war on the US a few days after Pearl Harbor.

America provided 450,000 trucks - which is THE thing that enabled the Red Army to supply its forces more than just very short distances from their supply bases. This was Germany’s single biggest weakness. They had to rely on horses which are slower, can’t carry as much and require far more manpower. The heavy American Studebaker trucks were what the Russians mounted their iconic Katyusha rockets on.

The list goes on and on. Everything you can imagine - especially industrial equipment. The Russians supplied the Manpower and paid a high price in blood - but there’s no way they survive without America’s vast supplies feeding and equipping them. — FLT-bird

The reality of the situation in December, 1941 is that it was exactly 1½ years after the Fall of France in June 1940.

Freedom's Forge:
How American Business Produced Victory in World War II
Arthur Herman
explains why that is significant. It is well known that the British did a major technology transfer to the US, but far less well known exactly when that happened. The Fall of France was a huge wake-up call for people who assumed until then that France, being a nation of similar size/population and similar technological/military base, would be able to fight Germany competently. France punched far below its weight class in 1940. The problem being that Colonel Charles de Gaulle was not commander in chief. He wrote presciently about the vulnerability of static defenses in the era of the tank and airplane - and the Germans proved him right. The French fought valiantly but, with the leadership they were saddled with, futilely. Lots of “dying for your country,” and not enough “making the other poor SOB die for his country.”
The Roosevelt Administration was alarmed that Britain too might fall, and take the Royal Navy over to Hitler’s side in a Vichy-like deal. Here I have to give FDR his due - although he was the reason the US economy didn’t recover in the 1930s from the fiasco which was the Hoover Administration, FDR did throw his weight behind Britain when it was necessary, and unpopular, to do so. After Dunkirk Britain’s army was practically denuded of weaponry - to the extent that Americans were sending their old guns over to Britain for their Home Guard. And FDR sent over all the WWI surplus weaponry he could scrounge up.
But back to the “eighteen months after the Fall of France” time. FDR was the original “pen and phone” man. He was able, by hook and by crook, to mobilize the US economy for military production without much help from Congress. Having been in the Navy Department during WWI, FDR knew that US military production had not amounted to a hill of beans by the time the Armistice was signed. So he called on financier Bernard Baruch to ramrod the mobilization in advance of critical need. Baruch declined the job on account of his age, and recommended “three names: Bill Knudsen, Bill Knudsen, or Bill Knudsen.”
Knudsen had lost a power struggle to be Henry Ford’s right hand man, quit, and took a job with a small competitor called, “General Motors.” You get the idea. Knudsen was a production expert, and he had the respect of industrial America. He immediately undertook to line up the long poles in the tent: factory facilities and especially machine tools. Others, such as Henry Kaiser, went to work on shipbuilding facilities. So for a long time, the watchword was not production per se, but production of the means of production. Of course ramping up the ability to produce included actual production - but it was not retained in America but shipped off to Britain (or, after Hitler's June 22 1941 invasion of the USSR, Russia).
Hence the paradox - upon America’s (official, up-front) entry into WWII, the US had very sparse military inventories - but that changed seemingly overnight. Most all of the production of the means of production was accomplished, and from then on it was just a matter of priorities how much of what got produced.