Well France tried to avoid confrontation and the U.K. was trying to hold on to its empire and contain the German threat, but also had many business interstate in Germany. The allies thought they could diplomatically outmaneuver Hitler.
France and the U.K. then caved to Hitler's demands repeatedly and essentially sold Czechoslovakia and Poland down the river to Hitler at Munich 1938, and during the "phoney war". France was then surprised by the swiftness of the German attack but capitulated very quickly. Her armies were still mostly intact when France fell.
It must also be remembered that the extent of collaboration in France under occupation was very great and the French resistance was always very small.
