^ these answers should be pertinent.
I wouldn't call them 'incompetent.' For one thing, 'French' in WWII encompasses the Army of 1940 and the Free French Forces, and the latter fought very well in Italy, North Africa and Northwestern Europe. The Army in 1940 suffered from poor communications and some poor decision-making on the part of Paul Gamelin, who sent the 7th Army to aid the Dutch and thus left the Army with no strategic reserve if the Germans broke through, which they did in the Ardennes. The French Army went on to fight well along the Weygand and Maginot Lines, and there was fierce fighting in Belgium as well. Leadership wasn't spotless in 1914 either, but in 1940 a number of poor decisions made the difference.