 During hearings in 1947 , Jack Warner included Rossen among the many openly leftist writers whom his studio , Warner Bros. , had hired as the earliest and most openly anti @-@ Nazi studios in Hollywood ( Warner Bros had made " Confessions of a Nazi Spy ' in 1939 and were attacked by GOP forces for this at the time ) . Warner reportedly accused Rossen of incorporating Communist propaganda in scripts and claimed this was why he had fired him , though in fact the real reason for Warner 's enmity with Rossen were his writer 's union activities . 
