sentences:  In 1941, Warner also produced the influential war film "Sergeant York".Contemporary reports that Jack Warner had banned the use of the German language throughout the company's studios were denied by studio representatives who indicated that this move would have prevented scores of studio employees from communicating with each other.After the American declaration of war against the Axis Powers, Jack Warner, like some other studio heads, was commissioned as a lieutenant colonel in the U.S. Army Air Corps.