French Military Planning During the First World War

During the 1920s there were serious concerns about the total number of Frenchmen available for military service, especially in comparison to Germany. The allure of a strong fixed defensive system is an understandable feeling. By providing the French army with strong permanent defensive works, less men could defend more territory. And what can justifiably be seen as a massive rejection of the overly optimistic French planning before the First World War?