France and Germany were not in good relations at all, and the main reason for this was that the two countries had military conflicts, mostly because of the German territorial and economic ambitions. Being attacked by Germany and having lot of damage because of it, made France very angry to its neighbor, so it wanted revenge at the first opportunity it will get. And so it did, as France attacked Germany and got part of it, while also causing lot of damage, both military and economic to it, thus the justice was somewhat satisfied in the eyes of the French.