This was an interesting book, up to a point. However, it did seem to talk a lot about the British effort for a book supposedly about France. There was also almost nothing about campaigns outside the Western Front, which I'm sure the French were involved in. However, it was interesting to see a little bit more about the Battle of Verdun which is almost always mentioned with regard to the Somme, but rarely gets much more than that. However, it does chart the progress and setbacks of the French Army well. The French did bear the brunt of the fighting in the First World War, but nobody seems to think about them...
The major problem the French faced at the start was their emphasis on the offensive. Even though the Germans were attacking and sweeping in through Belgium, the French had other ideas which blatantly ignored enemy action until it couldn't be ignored any longer. They launched their own offensive into Alsace-Lorraine, which was a major reason for the tension leading up to WWI as it had been taken at the end of the Franco-Prussian War. They had some success at first, but the troops had to be taken away from there and sent to defend France where the Germans had actually broken in. But the trouble was, the French were determined to counter-attack constantly, and to not give up any land. They were still wearing very bright uniforms (which the British had replaced before the Boer War in 1989 and further adapted after the experiences then which pointed out that shiny bits were not such a great idea), making them brilliant targets, and so when they counter-attacked they were decimated. This meant the army lost a large portion of its experienced men, particularly the officers as they tended to lead from in front.
Conscription had been part of the French military for a while, and in theory gave a sort of national unity. In practice, mixing up men from different areas of the country caused problems due to accent differences. It also destroyed the unity within the different regiments, who had originally been all part of the same community (like the Pals regiments), which Anthony Clayton suggests played a part in the French collapse of morale in 1917. This too is well portrayed, along with the way in which the army was pulled back into action.
At the end of the book, he suggests that the experiences of the First World War--a pyrrhic victory for the French in the end--was what led the French to collapse so fast in the Second. I don't particularly agree on that point. For one thing, although it would have permeated the social consciousness, they weren't the same people who were fighting again. Many people admired Hitler's style of government, and, as demonstrated by the creation of Vichy France, they were mostly okay to live under it (the Resistance, according to Churchill's Wizards did not really play much of a part in the ultimate downfall of Hitler and was never much more than a nuisance). In fact, even Gandhi thought Hitler was a decent enough chap at first. I have seen it argued that Britain shouldn't have fought Hitler at all, and certainly the French stood little chance of standing up to Hitler--half because of the lack of political unity, the lack of decisions, and the fact that their army had been run down. Further, there were a few blunders, which left them in an untenable position. It was pretty logical to surrender in that position, rather than attempting to sustain a resistance that could not have served any particular point.