Polish Blitzkrieg
It is easy for us to make decisions. We have nothing to lose; we have everything to gain. Because of our restrictions [Einschränkungen] our economic situation is such that we can only hold out for a few more years. Göring can confirm this. We have no other choice, we must act. Our opponents will be risking a great deal and can gain only a little. Britain's stake in a war is inconceivably great. Our enemies have leaders who are below the average. No personalities. No masters, no men of action.
--Adolf Hitler
So it was war. The Poles refused to surrender the Free City of Danzig to the Germans. Hitler, now, faced the first real roadblock to his authority.
Germany had faced worse odds before and been triumph. The Polish, with their cavalry and their antiquated army were not ready for a war in 1939. Nineteen years earlier had the Poles been tested against the nascent Soviet Union and had been victorious. But now, the Polish Army, weakened by infighting and a parasitic officer class, would not be prepared for the onslaught of German steel. Nazi Germanys command structure was cutting edge and while their army possessed less manpower than the Poles, they made up for it with their powerful Luftwaffe air force and motorized units.
But success was not guaranteed. The British and the French jumped at this violation of Polish sovereignty to declare war on Nazi Germany. The German people despaired at the prospect of a long, drawn out conflict with the Western powers.
Hitler, however, was not worried about such prospects. His tanks, under the oversight of Heinz Guderian, thundered across the Polish frontier. Within a couple of days, Danzig surrendered. Followed by Warsaw.
Followed by Warsaw.
Followed by Krakow
The Soviets honoured their part of the Non-Aggression pact; Poland completely surrendered by early October.
With such an astounding victory in such a short time and the Western Allies barely equipped for modern warfare, the stage was set for the most epic and bloodiest war in history.