Spain: American prisoners of war, presumably members of the Abraham Lincoln Brigade, released by Nationalist forces at Hendaya, Spain, 1938 The Abraham Lincoln Brigade was a group of volunteers from the United States who served in the Spanish Civil War as soldiers, technicians, medical personnel and aviators fighting for Spanish Republican forces as part of the International Brigades, against the Fascist forces of Francisco Franco and the Spanish Nationalists.<br ><br > Of the approximately 2,800 American volunteers, between 750 and 800 were killed in action or died of wounds or sickness.