For a long time I have been curious about this.
French military [and the British for that matter] having gone to war in 1939 not pursuing a more aggressive combat status. French troops assuming a defensive posture and venturing east the Maginot Line but in a very tepid and uninspired manner.
FRENCH MILITARY THE OFFENSE "TEPID AND UNINSPIRING" EVEN WHILE POSSESSING A SIGNIFICANT AND PERHAPS OVERWHELMING ADVANTAGE SO IT WOULD SEEM. GERMAN TROOPS GUARDING THE WESTERN WALL [SIEGFRIED LINE] AND THE GERMAN BORDER WITH FRANCE OUTNUMBERED AND OUTGUNNED.
Herewith a Mark Felton You Tube video the French offensive of 1939 elaborated upon.
French troops their advance into German territory relatively minor [four miles slightly more than six kilometers]. Advance but then rather quick withdrawal. Back to the Maginot Line. And why was this? French manpower, artillery and armor far more than the German. A concerted action if pressed could have gone much further and greatly relieved the pressure on the Poles? French armor more numerous than the German counter-part and far [?] better, more or less impervious to German anti-tank weaponry.
Historical reasons for lack of French resolve in 1939 usually listed as:
1. French politicians hesitant for fear of excessive casualties.
2. Siegfried Line thought to be too heavily defended and too strong [it was not].
3. French lacking an adequate supply train to support and sustain further combat forward action.
4. The Soviet Union occupying half of Poland as had been agreed with Germany. The French perceived [?] further combat on behalf of Poland would have meant a possible tussle with the Soviet Union too?
The French archives from the period can be gleaned if they exist anymore and will tell us what we need to know? I am skeptical.