User blog comment:Disturbedfan1100/Diplomatic talk and stuff/@comment-5593482-20131210172853

Just to clarify, Poland never officially helped the USSR. Sure Polish soldiers fought on the Eastern front, but those were mostly drafts from Eastern Poland which the Soviets annexed. Poland tried to revolt and liberate itself from the Germans on its own. This attempt is known as the Warsaw uprising. It didn't succeed because the Soviets failed to give any support to the Poles fighting. They let the Poles and Germans bleed eachother out and then rushed to exploit the German setback after the uprising failed.

Weather Barbarossa could succeed at all is debatable. But if Barbarossa was not launched, we can be certain that the Soviets would launch their own invasion.