This has elements of a '30s-style aviation picture (e.g. Only Angels Have Wings) and a WWII air force morale booster. Before Pearl Harbor, a bunch of American civilian pilots in China operate their own squadron, flying for Chiang Kai-shek. Cowards redeem themselves, cynics see the light; sidearms are worn as routinely as in a Dodge City saloon, about the only detail that strikes one as authentic. Did this sort of thing boost morale? Did the sight of the Duke in his fake cockpit, smiling grimly at some interpolated newsreel carnage, really offer aid and comfort, except to schoolkids? Remarkable, if so.