The combined German and Russian invasions of Poland in September 1939 were disastrous for the Polish people. The Germans invaded on September 2, and the Poles fell back before the onslaught at first. (The Germans did not actually practice blitzkrieg in Poland, but the invasion was still a swift one.) The Poles ceded some territory, and fell back to defensive positions further east…
…and then, on the 17th of September, and without any formal declaration of war, the Soviets invaded from the east. Caught between two armies, either of which by itself was numerically superior to the Polish army, there was little chance of victory. Although Britain, France and their respective allies had entered the war on the Polish side, they could not deploy in time to give any assistance to their beleagured ally. The Poles fought hard, and inflicted great casualties on the Germans and Russians, but the result was never truly in doubt.
Although some units fought on, the war in Poland largely came to an end with the fall of Warsaw on September 27, 1939, and the Polish government in exile was officially formed on the following day.
To Be Or Not To Be (The Hitler Rap) – Mel Brooks