I had this idea for WW2 scenario in 1939. So let's say the Molotov-Ribbentrop pact never happens or it fails and the Soviets align with the British and the French in a negotiation which did happen in OTL. So in this alternate scenario for heavens sake have Germany invade Poland in August 1939 but the Allies, along with the USSR, declare war on Germany. How would the war go? How would Poland react to letting its feared enemy into the territory for assistance? How powerful would the USSR be against Germany? What would happen to the Western front? What about Italy? How long would the war go? How would this change 20th century timeline?