Steve Nelson ( activist ) Stjepan Mesaros , best known as Steve Nelson ( 1903 – 1993 ) was a Croatian - born American political activist . Nelson achieved public notoriety as the political commissar of the Abraham Lincoln Brigade in the Spanish Civil War and a leading functionary of the Communist Party , USA . Nelson is best remembered for having been prosecuted and convicted under the Smith Act in 1953 . Biography . Stjepan Mesaros ( " Stephen Mesarosh " ) was born in Subocka , Croatia on January 1 , 1903 of ethnic Hungarian extraction . The Communist Party of the United States would later claim he was born in Steelton , Pennsylvania . Mesaros emigrated to the United States of America with his mother and three sisters 1919 . He started working in a Pittsburgh , Pennsylvania slaughterhouse and meat - packing plant . A succession of blue - collar jobs followed . Political career . In 1923 , by now using the Americanized name " Steve Nelson , " he joined the youth section of the American Communist Party , the Young Workers League . He went on to join the adult Workers ( Communist ) Party in 1925 . He met Margaret Yaeger , a typist in the Pittsburgh office of the Party . They married and went to Detroit in 1925 , where he worked in the auto industry as an assembly line worker and union organizer . In 1928 the Nelsons moved to New York City . Nelson studied Marxism at the New York Workers School and afterwards , with the onset of the Great Depression , the Nelsons worked for the Communist Party full - time . Nelson organized the International Unemployment Day demonstration on March 6 , 1930 , at which he , Joe Dallet and Oliver Law were beaten up and arrested . Two weeks he was among the 75 , 000 demonstrators to demand unemployment insurance . Nelson and his wife were sent to Moscow in 1931 , he visited the International Lenin School for two years . He was a courier for the " Communist International ( Comintern ) " , delivering documents and funds to Germany , Switzerland and China . On return to the United States in 1933 , they settled in Wilkes - Barre . In 1937 he immediately tried to join the Abraham Lincoln Brigade , but had to stay in Pennsylvania where he agitated coal miners . After the severe setback at Jarama , Nelson , Joe Dallet and 23 others were allowed to fight in Spain . At first arrested by the French , they reached Spain climbing the Pyrenees mountains and met the International Brigades at Albacete in May 1937 . Nelson started the war as political commissar of the Lincoln Battalion . After heavy loses at Brunete the Abraham Lincoln Battalion and the George Washington Battalion were merged into the Lincoln – Washington Battalion . Mirko Markovicz , a Yugoslav - American , was appointed as commander of the Lincoln – Washington Battalion and Nelson became his political commissar . In August 1937 the American forces were reorganized . Nelson was promoted to brigade commissar and Robert Hale Merriman became brigade chief of staff . Hans Amlie became commander of the Lincoln – Washington Battalion . In the fighting at Belchite , which started very bad , only two soldiers of twenty - two survived a first attempt to take the church of the town . Nelson then led his men in a successful diversionary attack and Amlie ' s men could enter the fortified town . Nelson was shot in the face and leg , Merriman and Amlie received head wounds . After recovering in Valencia , Nelson was given the task to escort prominent visitors like John Bernard , Dorothy Parker and Ernest Hemingway . In the 1940s , Nelson rose to the top ranks of the communist party . After years on the West Coast , the Nelsons returned east , when he was elected to the National Board of the party . He settled in Pittsburgh as District Secretary of Western Pennsylvania . Legal difficulties . In August 1950 , after a raid on the Pittsburgh Party Headquarters , Nelson and two local party leaders were arrested and charged under the 1919 Pennsylvania Sedition Act for attempting to overthrow the state and federal government . Nelson initially received a 20 - year prison sentence , $ 10 , 000 in fines and $ 13 , 000 in prosecution costs . He was jailed in Pittsburgh for seven months and then released on bail pending his appeal . In 1953 he and five others were indicted under the Federal Smith Act . This time the fine was 5 years and $ 10 , 000 . All six were granted bail . In 1956 in Pennsylvania v . Nelson , the United States Supreme Court overturned the Pennsylvania Sedition Act , saying that the Federal Smith Act superseded this and all similar state laws . In the same year testimony at the first trial was found to have been perjured and a new trial was granted . In 1957 the government dropped all charges against the defendants . Later years . Nelson left the Communist Party in 1957 after Nikita Khrushchev ' s revelations about Stalin . In 1963 he became the National Commander of the Veterans of the Abraham Lincoln Brigade ( VALB ) . In 1975 he retired with his wife of 60 years to a home he had built in Truro , Massachusetts on Cape Cod . Death and legacy . Nelson died in December 1993 at the age of 90 .