This may seem an odd ritual, but whatever else one might say about the nature of monolithic Communism, it remains that Russians are patriotic, too, and when it comes to World War II (the Great Patriotic War, in regional usage), they have good reason. In 1985, in Leningrad, it had been only a little more than four decades since the end of the city's 900-day siege, during which a half-million people dies, most of them civilians.
By contrast, Chicago experienced no such privation during the war. I'll merely note that a fairly dispassionate explanation of the Soviet wartime experience can be found here.
Why am I offering this information today? Primarily as a corrective to the jingoism and chest-thumping that accompany the July 4 holiday. History isn't that simple, and while WWII is now a distant memory, and vast chunks of the American populace knows little about it and will not consider the historical record on a day devoted to eating, drinking and varied debaucheries, it still matters to me. Russians paid a very high price to bleed the Nazis dry on the steppes.We shouldn't forget that, Putin or otherwise.
The successful 70-year campaign to convince people the USA and not the USSR beat Hitler, by Dylan Matthews (Vox)
... Assessing the "biggest contributor to victory" in a rigorous way is exceptionally difficult. They tend to devolve into comparisons of counterfactuals, and the truth is that nobody has any strong idea how the war would have turned out absent US involvement, or if the German-Soviet non-aggression pact had held, etc. But the case is pretty strong that the Soviet Union's successful resistance of Nazi invasion and subsequent reclamation of Eastern Europe was the most important of many crucial factors in defeating Germany.