From the Outbreak of the War to the Fall of France (September 1939-July 1940)
The German High Command's (OKH) operational orders for the attack on Poland, codenamed 'Plan White', were finalized on 15 June 1939. Although Hitler was confident that Britain and France posed no serious threat, mistakenly believing that their attitude had not changed since Munich and that they would continue to prevaricate and appease, the Wehrmacht was less optimistic. For this reason the plan called for a swift campaign so that troops could be withdrawn to make up for the deficiencies of the 'West Wall', a defensive system which had not yet been completed and which was only lightly manned. A rapid campaign would also make it possible to crush the Polish army before it had time to complete its mobilization and before it could be fully deployed to the west of the Vistula and the Narew.
The plan called for a two-pronged attack centred on Warsaw: Army Group North swooping down from Pomerania and East Prussia, and Army Group South advancing from Silesia and Galicia. Only a handful of troops were ordered to take Danzig. The major problem for the planners was that Army Group North had both to secure the Polish Corridor and to advance towards Warsaw. Forces had also to be ready to encircle Polish units able to escape this massive pincer movement by moving to the east of the capital. For this purpose, tanks were ideal.
To give the political leadership maximum freedom of action, mobilization had to be swift and secret and thus could not include industry and the civilian population. Hitler ordered a 'mobilization without a public announcement' to take effect on 28 August, by which time the army had been increased by three million men. A series of manoeuvres and exercises was carried out from the end of