This is ignoring the secret protocol in which the USSR and Nazi Germany carved up eastern Europe into spheres of influence: https://avalon.law.yale.edu/20th_century/addsepro.asp And yes it does mention carving up Poland, it describes what the border should be if Poland is invaded (wink wink) and then declares that leaving a Polish rump state or not will be decided later. It also in no uncertain terms states that the Soviets can take Bessarabia.

It is the only non-aggression pact with such a protocol. The western powers did not sign such a deal with the Nazis in which third-parties are carved up.

Negotiations between the west and the USSR broke down for several reasons, notably:

Deep mutual mistrust, in part due to the mass terror and the purges in the USSR, and notably France failing to make good on an earlier promise for a military agreement. Both sides believed the other might abuse a pact to draw them into war with Germany.
Disagreement over the Baltics; the USSR believed Hitler would attack through those states, but the west did not want to commit to security guarantees to states that did not want them (Estonia and Latvia rejected them, fearing it would incense the Germans).
Once the west finally yielded on guaranteeing the Baltics, the USSR refused to do the same for the Netherlands, Luxembourg and Switzerland.
The USSR demanded that in case of war, the Red Army would be given free passage through Poland and Romania. The west told the USSR that they'd have to negotiate that with those countries themselves, and they could not unilaterally allow it without having either country agree.
There was disagreement over what would constitute "indirect aggression", eg what the Nazis did to anschluss Austria.
The USSR kept hammering on immediate, unconditional action in case of war with Germany. The west wanted consultations first, as they were worried the USSR would do something in the Baltics to trigger war with Germany, drawing the west in for a cause they might not support.
The west had little motivation to push for a pact, as it had already provided security guarantees to Poland and Romania. The only other land access route was through Memel into Lithuania, but Lithuania had ceded Memel and signed a non-aggression pact with the Germans, so the west did not think an attack over the Baltics was as likely as the Soviets believed it was.

Ultimately the security guarantee on Poland brought the west into war with Germany. The USSR, despite hammering on immediate action against Germany during negotiations before, instead opted for the annexation of the Baltics, Bessarabia and eastern Poland, and an attack on Finland. It took nearly two years for the USSR to begin fighting the Nazis, and only because the Nazis invaded them first.

No notes on Churchill being a dickhead though.

[–] Edie@lemmy.ml 4 points 3 hours ago

the Red Army would be given free passage through Poland and Romania

Poland makes sense, but why Romania?

[–] Cowbee@lemmy.ml 3 points 3 hours ago

The Soviet Union did not agree to invade Poland with the Nazis, it was about spheres of influence and red lines the Nazis should not cross in Poland. Spheres of influence were not agreements to jointly work together. When the USSR went into Poland, it stayed mostly to areas Poland had invaded and annexed a few decades prior. Should the Soviets have let Poland get entirely taken over by the Nazis, standing idle? The West made it clear that they were never going to help anyone against the Nazis until it was their turn to be targeted.

Further, you're ignoring the Munich Agreement, where Czechoslovakia was given to the Nazis by the west. Not only was the west on good terms with the Nazis, signing many non-aggression pacts, they fostered healthy relationships. Finally, the Soviets were reasonably highly suspicious that Britain and Germany would ally. This was not unfounded, both were friendly enough until the outbreak of war. The Soviets desperately needed to make sure that the British and Germans would not ally, which reasonably would have happened had the Soviet Union taken unilateral action against the Nazis, rather than waiting to be attacked first.

Stalin was said to have "obsessed over quantitative and qualitative" improvements in arms in the years leading up to World War II, and had soldiers stationed on high alert, preparing for a German attack. Despite the insistence of many Generals to muster forces on the German border, it was Stalin's insistence that forces not be so concentrated that prevented the Nazis from totally routing the Red Army, enabling the greatest counteroffensive in history.

Hitler himself was quite honest at times, to himself at least:

How can such a primitive people manage such technical achievements in such a short time!

...

The fact that Stalin has raised the Russian standard of living is unquestionable. People don’t go hungry [at the moment when Operation Barbarossa was launched]. In general, it’s necessary to recognize that they have built factories of similar importance to Hermann Goering Reichswerke where two years ago nothing but unknown villages existed. We come across railway lines that aren’t even marked on our maps.

The Soviets expected and planned for it, they were never allies with the Nazis.