France was invaded by Germany and defended by Great Britain to start World War I in August 1914.  A rich industrial area in the northeast was occupied. France and the Allies emerged victorious against the Central Powers at a tremendous human and material cost. World War I left 1.4 million French soldiers dead, 4% of its population. Between 27 and 30% of soldiers conscripted from 1912 to 1915 were killed. The interbellum years were marked by intense international tensions and a variety of social reforms introduced by the Popular Front government (annual leave, eight-hour workdays, women in government).