Complex sentence: Begun as the independent organ in response to the Workers Party of America take over of "The Liberator", by the late 1930s it strongly backed the Communist Party USA's Popular Front movement as a response to the rise of fascism and the Spanish Civil War.
Split into simpler sentences: Begun as the independent organ in response to the Workers Party of America take over of "The Liberator". By the late 1930s, it strongly backed the Communist Party USA's Popular Front movement as a response to the rise of fascism and the Spanish Civil War.