FDR and Churchill let Stalin take eastern Europe, restraining Patton and his idea to rearm the Germans and attack the Russians and drive them back to Russia. I wonder why this outcome to the war was acceptable to them yet Hitler doing much the same as Stalin was bad and wrong and worth fighting over.
The Germans had real combat experience with their new combined arms blitzkrieg tactic in France and Poland, they knew how best to use what they had from real world experience. Nothing Poland had was up to the task as far as war materials save in sheer numbers, the Poles still had and used cavalry against German tanks and machine gunners with the expected results, Poland had similar numbers of men in the field but it just swelled prisoner of war camps. The Poles flew biplanes against ME109s and were slaughtered, of course the same happened to Russia early in the campaign. The Russians were stockpiling armor just across their new border with Germany at the time Germany attacked, and this armor would be suitable to take on men and lightly armored vehicles as one might find at the end of a long drawn out war between France, England, and Germany, but not against the armor the Germans (and French) had then, much less an answer to German tactics. The Russians lost thousands of tanks and planes in the first few days, this likely added to Stalin's initial depression as the numbers of men and machines destroyed were really fantastic and hard to accept, so many destroyed tanks and planes had been claimed by German forces that Hitler himself had to investigate weather it was true.
This is a link to Hitler and Mannerheim discussing what Germany found inside Russia, note the commentary regarding 35k tanks and a tank factory that had shifts of 60k workers;
https://www.youtube.com/watch?v=oET1WaG5sFkStalin was up to something but was undone by another megalomaniac.
This 100 kilometers a day tank advance common in the initial days in the Russian campaign wasn't the case in the west when Germany invaded France, the top tank in western Europe was the French Char B, much thicker armor than any German tank in the field and superior to anything Russia then fielded. One of the problems for France was Germany had infiltrated their intelligence guys into France just before the attack and were using French telephone networks against the French. What this resulted in was fake reports being accepted as fact by civilian and military authorities and the encouragement of French civilians to flee and clog the roads for miles, hindering French military response to a fantastic degree. This communications trickery never gets mentioned as a deciding factor in the defeat of France, but how France used their superior tanks should take the blame. If the French had employed their tanks as the Germans did theirs, there's a good chance France would have rolled the Germans back over the borders, but instead of combining their tanks in an army they allotted them out in little packets here and there where their presence didn't really amount to much. When the French decided to mass their armor it was too late, but their one massed armor attack severely hindered the German supply train, the focus of the attack.
Here's a link to a book by a guy who was present in German signals intelligence in ww1 and ww2, if you're into this stuff it makes great reading. The author wrote his experiences a few years after ww2 and the US Gov/future nsa bought the rights to it as it revealed some methods used against the Russians the allies wanted to remain secret. For a few years you could hardly find these works anywhere and only in print, and one day I found nsa had released them entirely as pdfs on their own webpage but now apparently the nsa has decided to no longer host them so here's an external link;
https://cryptome.org/2015/04/nsa-war-secrets-in-the-ether-p1-p2.pdfhttps://cryptome.org/2015/04/nsa-war-secrets-in-the-ether-p3.pdfWhat all this combat experience in Poland and France added up to is the Germans exacted 11 Russians for every German casualty. Apparently for the western allies the Germans inflicted twice as many casualties as they took. Better training, better tactics, in some cases superior arms. Tyrants like Stalin and Zhukov had no issue ordering masses of men to their deaths to attempt to take an objective, they had the men to dispose of as they wished. Germany had some 70 million population, Russia has 189 million people in 1939 so you can see Russia had cannon fodder to spare. America was similar in some respects to Russia as we had no shortage of manpower or materials so our generals were willing to risk their men as if it was nothing, while the Brits used tactics and superior firepower to reduce the Germans obstructing them as the Brits at home would not stand mass casualties that barely rated notice in the US and was laughed at in Russia.
Some asides;
When Germany invaded Poland, France invaded Germany.
The French crossed the border and took some barely defended towns/villages and met little opposition, then they retreated back to France! This put Hitler and his general staff in a panic as almost all his forces were inside Poland and nowhere near the French border, they knew they couldn't stop the French. The way was clear all the way to Berlin, and the French retreated, and instead of French Poilus parading past the Brandenburg Gate (in Berlin) in Triomphe over Nazi Germany, Hitler's landsers paraded in Paris every day.
This folly was followed by one of Germany's making. After Dunkirk, England had no armor or artillery to speak of, it was all abandoned on the shores of France. Hitler had most all his forces, forces with fresh combat experience, within visible distance of the cliffs of Dover. If Hitler had made the effort, England likely would have been his. Then he could have focused on Russia.
The next folly was Germany's too. When Goering had RAF fighter command on the ropes with bombing their bases and shooting down Brit fighters, he changed course mid stream and bombed cities instead of RAF bases, apparently a Brit bomber formation had bombed a German city and so the Germans wanted to exact vengeance. Once again Hitler snatched defeat out of the jaws of victory.
Another folly was Hitler divided his forces and sent them off the road to victory when Moscow was in sight, as in his soldiers could actually see Moscow. He sent some armies down south to take oil wells in the Caucasus, and some up north to take Stalingrad and so on. Lost at Stalingrad, never set foot in Moscow. Never saw the several divisions of arctic trained Soviet troops with their new T34 tanks that worked at -60f, unlike German tanks, that were about to snap shut the jaws of a steel trap around the 7th Army until it was too late.
Sorry, I'm a huge ww2 nerd and being able to vent is cathartic.