Cleveland's contribution to the war front began on May 25, 1917, with the Lakeside Hospital Unit becoming the first American detachment to land in Europe. On the home front, the war accelerated the growth of Cleveland, which became the fifth-largest city in the nation by the end of the decade. When war broke out, Cleveland's growing industries could no longer depend on the labor emigrating from Europe. At the same time, 40,000 Clevelanders would eventually leave the workforce and serve in the military. Women replaced them in jobs that were not available in the past. Scores of African Americans left the South, and this Great Migration led to significant economic, social, and political developments in the coming years. Cleveland's ethnic neighborhoods included many who had come from the nations and regions of the Central Powers. Americanization programs taught immigrants English and patriotism.