 The American historian William Keylor wrote that given the diplomatic conditions of 1929 and likely trends – with the United States isolationist and Britain unwilling to make the "continental commitment" – the decision to build the Maginot Line was not irrational and stupid, as building the Maginot Line was a sensible response to the problems that would be created by the coming French withdrawal from the Rhineland in 1930.Part of the rationale for the Maginot Line stemmed from the severe French losses during the First World War, and their effect on the French population.The drop in the birth rate during and after the war, resulting in a national shortage of young men, created an "echo" effect in the generation that provided the French conscript army in the mid-1930s.