sentences:  Principal photography for "The Purple Heart" began on October 11, 1943 and continued to mid-January 1944.Zanuck and a team of writers endeavoured to ensure that the story was based on documentation and unofficial collaboration of the torture suffered by the prisoners, and "... should be almost documentary in its honesty ..." The United States Office of War Information (OWI) reviewed the script and was able to suggest some changes to strengthen the role of the Chinese civilians who had helped the Doolittle Raiders.