Many thanks to CptdeS35. I didn't really know all that. As it is stated even French people might be unaware of it, so thank you for that information. I assume that the invasion of Netherlands and Belgium broght a critical change to the assumptions on which the Allied defensive plans were build before the war.
Many thanks to vonMudra too, for the information about how the Polish defence worked. This makes the passive attitude of the allies even more regrettable.
Poland and Romania had signed several treaties ending in the "Treaty on Mutual Assistance against Aggression and on Military Aid".
http://en.wikipedia.org/wiki/Polish-Romanian_AllianceThere were even ucrainian territories occupied mainly by Poland (before the war) to make up a border with Romania. There was a worst case plan: the Romanian Bridgehead, but after the russian Invasion it was no longer used.
http://en.wikipedia.org/wiki/Polish-Romanian_Alliance#Outbreak_of_World_War_II Instead 120 000 Polish troops were evacuated from there to Western Europe. Romania also helped hide a big amount of the Polish treasury from the Reich and later the SU until it could be returned to Poland.
The passive stance of the allies made Romania choose to join Axis, which I regret, but while Poland lost 6 Mio. civilians, the loses in Romania were comparable with other nations so it was the "right" decision as well as the French one to avoid the war. Though as I said, France was not threatended on two fronts like the eastern european states.