Fresh were memories of the Polish-Soviet War and the Battle of Warsaw, which saved Poland and the rest of Europe from the spread of the Bolshevik Revolution by force.
It was only after 1935, when anti-Polish propaganda in Germany increased, that the German threat became visible enough for army planners to begin drawing up Plan West.
The south, formerly a portion of the Galicia province of Austria-Hungary, was the most highly-developed area, with ita high density of rail lines, growing amount of industry (such as oil fields in Boryslaw) and well-developed agriculture of Podolia.
[5] Virtually all Polish industrial and urban centres were in the west and so a long-lasting defence was possible, as a Soviet force would have taken up to several weeks to reach Upper Silesia, Warsaw, Kraków or Poznań.
When they developed the plan, Polish planners assumed that co-operation and support would be forthcoming from Romania, which was Poland's main eastern ally.
The most famous one was the attack on Stolpce, which took place on the night of August 3–4, 1924, which prompted the creation of the Korpus Ochrony Pogranicza (Border Protection Corps).
Therefore, the main idea was to organize a so-called "resistance in motion" and to try to split Soviet forces south and north of the vast Polesie swamps.
Frontline armies, in the vicinity of the border, were to try to delay the advance of the aggressors and to bleed them, and reserves, mostly in the areas of Brześć nad Bugiem and Lublin, were intended to enter the conflict in its later stages.
Some military historians claim that Polish planners placed too many units close to the border, which would have resulted in their total destruction in the opening days of the conflict.
In August 1939, along the Polish border were likely as many as 173 Red Army infantry divisions (see Soviet order of battle for invasion of Poland in 1939).