Population of France in 1914: 41 million, Germany 67 million -- a difference of over 50%. The French population only grew from 36 million to 41 million from 1870 to 1914, while in contrast, Germany's population grew from 24 million in 1870 to 67 million by 1914 (1910 census: 65 million).
Even then, the French held the German armies back at Verdun -- the Germans could have avoided a two-front war if they had renewed the Reinsurance treaty in 1890 and Russia would not have intervened -- remember that it was the German plan for this war.
A war between Germany (81 million) and France (67 million) is unthinkable and impossible now, but in the event of this now, the French have a far more active army (they keep getting involved in their pseudo colonies in West Africa) than the Germans so a straight fight would see a French victory right now.
“A war between Germany (81 million) and France (67 million) is unthinkable and impossible now”
I did not see us getting into a kinetic military action with Lybia two weeks ago.