- suffered extensive destruction and/or over-exploitation in the case of mines and factories, reducing their output. Prime agricultural land had been ruined and livestock lost. 27% of young men between the ages of 18 and 27 were killed, with a consequent negative impact on marriages and births which would impact the labor force in the 1930s. Fertility rates sharply declined during the First World War, with the deficit of births estimated to be 1.4 million. Combined with an equivalent number of casualties, the French population was 2.8 million people smaller than it otherwise would have been due to the war. At the Paris Peace Conference, 1919, vengeance against defeated Germany was the main French theme. France demanded full payment by Germany of the damages it imposed in the German-occupied areas. It also wanted the full cost of postwar veterans benefits. Prime Minister Clemenceau was largely effective against the moderating influences of the British and Americans. France obtained large (but unspecified) reparations, regained Alsace-Lorraine and obtained mandates to rule parts of former German colonies in Africa. In January 1923 as a response to the failure of the German to ship enough coal as part of its reparations, France (and Belgium) occupied the industrial region of the Ruhr. Germany responded with passive resistance including printing vast amounts of marks to pay for the occupation, thereby causing runaway inflation. Inflation heavily damaged the German middle class (because their bank accounts became worthless) but it also damaged the French franc. France fomented a separatist movement pointing to an independent buffer state, but it collapsed after some bloodshed. The intervention was a failure, and in summer 1924 France accepted the American solution to the reparations issues, as expressed in the Dawes Plan. Industrial productivity returned to pre-war levels by 1924 and by 1929 it was 40% above 1913 levels. The French government eased immigration rules to offset the manpower shortage - some 2 million workers arrived in France as a result. Inflation was a serious problem, fueled by high government borrowing and a huge increase in the amount of money in circulation (37,900 million francs were in circulation at the end of 1920, compared to 6000 million in 1914). Consumer prices doubled between 1922 and 1926, and the franc suffered continual devaluation (in 1914 one British Pound was worth 25 francs, by July 1926 one Pound was worth 243 francs). The devaluation of the franc