Plan West

After German annexation of parts of Czechoslovakia and changes of borders, Polish planners revised the plan with the expectation that a main thrust would originate from Silesia through Piotrków and Łódź towards Warsaw and Kraków.

[5] The western regions were also the most densely populated ones and had major industrial centres, which were crucial for mobilization and any continued military production of equipment and supply for the Polish Army.

[1] The plan assumed that Polish forces would be able to hold for several months but would be pushed back by the German numerical and technical superiority, which was estimated to be two or three to one.

[2] When the Germans attacked, however, the second and further defensive lines and related items were not fully defined by the plan, and none of its aspects had been subject to a military exercise.

[2][7] When Germany invaded Poland on 1 September 1939, Polish forces were dealt a significant defeat at the Battle of the Border, just as critics of the plan had predicted.