German members of the International Brigades; Madrid, Spain - November 1936 Photo by Robert Capa The majority of those participating had communist or socialist backgrounds and were of the working class. Some men who left Nazi Germany to fight among the Republican forces against the Nationalists were World War I veterans who had experience fighting in paramilitary organizations during the years of the Weimar Republic.
Battle of Teruel, Aragón front. Spain. Loyalist soldiers carrying away the wounded during the battle for this strategically located hilltop town on one of the major routes to Barcelona. By Robert Capa, (December 1937-January 1938)