For four long years, from 1914 to 1918, the war had created vast movements of displaced populations, civilians who had to flee ahead of invading troops, or who were driven out by force during military occupations on both the Western and Eastern fronts. From 1918 to 1922, large numbers of refugees continued to be on the move in Europe. The collapse of the vast multi-ethnic Austro-Hungarian, Russian, and Ottoman Empires had given birth to smaller nation-states that often forced ethnic minorities to leave. The refugee groups included many people driven from their homes by war, religious persecution, or poverty. Several hundred thousand Magyars were expelled from Romania, Czechoslovakia, and Yugoslavia, and migrated to Hungary. After the war, when Alsace-Lorraine returned to French control, the government classified its population into four categories and deported thousands of ethnic Germans during the winter of 1918–19, even if they no longer had any contact with or ties to Germany. Russian refugees fled from oppression, poverty, and hunger. After the genocide of 1915, in which over a million Armenians died, survivors fled to Soviet Armenia, Syria, and other countries.