There's an assumption on these boards that a scenario such as a failed D-Day, no American intervention in the European War, or white peace between Britain and Germany, would lead to the Red Army marching all the way into France. I wanted to test how plausible that assumption really is.
For example, the operational distance from the USSR to France is vast - would a war-weary Soviet Union, that has had to fight an even greater share of Nazi Germany's war resources than OTL, be able or willing to project force into France? The logistics of moving war materiel another 500 miles from Berlin to Paris, a 50% increase on the distance from Moscow to Berlin, would be difficult - even with the comparatively better infrastructure of Western Europe.
In addition, though the French Communist movement was a significant part of the underground (and strongly Soviet-aligned), and could arise to fill the power vacuum that resulted from a fallen Wehrmacht, there's no reason to assume that a British-sponsored government-in-exile would be completely incapable of doing the same. The same argument goes for governments in the Low Countries.
Would fighting even continue to the point where the Red Army would be near France and the Benelux at all? Geographically Berlin is closer to the east and would fall sooner than the rest of Germany. We know that Nazi Germany fought to the last inch of territory but would a fall of Berlin comparatively early in a Soviet conquest of Germany mean an earlier capitulation, perhaps without total subjugation of the territory? I concede it is likely that the Soviet Union may have to fight all the way to the Rhine, a task that could take them well into 1947 or further. But again, I am unsure that this would lead to a communist France beyond it.
While we are on the topic - is it really fair to assume that this would lead to a communist Italy as well? The Alps are a formidable natural barrier and it is questionable if fascist Italy would be willing to entertain a losing war with the Soviets to the point where it could be invaded. I would pair that possibility with the idea that a war-weary Soviet Union may well decide to make peace with a Petain-led, authoritarian Vichy France armed with impressed German weaponry, simply due to the logistical nightmare of fighting beyond the Rhine - and with grizzled troops unwilling to continue fighting when the Nazi menace has already been beaten.
The answer may well be 'yes, the above scenarios could plausibly lead to the Red Army on the Channel' - but I'm not convinced, and I'm curious to hear what the forum thinks.