Definetely worth the read, detailed and easy-to-read documenthttp://ibiblio.org/hyperwar/Germany/DA-Poland/DA-Poland.htmlWAR DEPARTMENT,
WASHINGTON, March 31, 1942.
Digests and Lessons of Recent Military Operations--The German Campaign in Poland, September 1 to October 5, 1939, is published for the information of all concerned.
This digest has been compiled from War Department reports and from other governmental and authentic professional military sources. [A. G. 062.11 (1-26-42).]
BY ORDER OF THE SECRETARY OF WAR:
G.C. MARSHALL,
Chief of Staff.
Introductory
Historical sketch
Strategy, initial dispositions, and missions
Operations
Lessons
Digests and Lessons of Recent Military Operations
The German Campaign in Poland
September 1 to October 5, 1939
1. Introductory.-The Army of the Third Reich was unleashed completely for the first time in the Polish campaign, which was a preview of German strategy, tactics, and technique. In 20 days of fighting the new German military machine annihilated the Polish armies; Warsaw capitulated after 27 days; and the last point of resistance was subdued in 35 days. Undoubtedly this swift victory was due in great measure to the overwhelming superiority of the German Army in both numbers and materiel, but of equal importance was the fact that the German High Command had learned vital lessons from the stalemates of position warfare in the first World War.
New German concepts of warfare that materialized fully on Polish battlefields started a new military era marked by the return of the war of movement. The mobility and speed made possible by extensive motorization, together with the increased fire power and shock force of armored corps and divisions, and the close support of bombardment aviation, restored to all ground arms the ability to maneuver. The need for more intensive and closely coordinated sup‚porting fire was filled by developing the air-infantry-artillery combat team to a new peak of efficiency. And air power demonstrated radi‚cally improved strategic as well as tactical capabilities.
While developing these factors of speed, fire power, air power, and the ability to maneuver to a degree of effectiveness never realized before, the German Army, in its training, had devoted itself intensively to the coordination of the separate arms. The German victory over Poland was achieved not by the shock action and penetrations of armored forces alone, nor by air power alone, but by the combined operations of all arms under unified command.
Finally, the German Army was indoctrinated with the idea of total war-the idea that all the resources of the nation must be concentrated ruthlessly and relentlessly against all important hostile means of resistance in order to win a swift and complete decision.