From an article I found about William Wyler's wartime service:
Wyler joined the USAAF to ‘see if I could make a film that would help the war effort in some small way.’ He made a film which focussed on the final, 25th mission of one aircraft and crew – Captain Robert Morgan’s B-17 ‘Memphis Belle’. Wyler recalled the difficulty of filming the live action: ‘things happen so fast… Messerschmitts and Focke-Wulfs coming at you and you would try to get all this on film. You forget that they’re shooting at you at the same time!’ When President Roosevelt saw the finished film, he said to Wyler: ‘This has to be shown, right away. Everywhere.’