Originally Posted by pj67coll

To be blunt. They weren't that stupid. They knew perfectly well that they would not be able to beat Germany on their own. They needed Russia to do their fighting for them. This was clearly not going ot happen if they went to war with the Russians at the same time as with the Germans. Remember, the French even had a defence pact with the Russians prior to the German attack on Poland. Dont forget also that both their governments were shot thru with commie deputies and sympathisers prior to the war.