I think he flew 25 missions over Germany. If I'm not mistaken that was the number of missions a bomber pilot or crewman had to complete before he could go back to the states. I think Clark Gable also flew on quite a few missions over Germany. I say "flew on" missions because I don't think he was an actual pilot or co-pilot. Stewart, Gable, Fonda, and quite a few of the WWII era Hollywood actors were involved in combat or some other type of actual military service during WWII instead of just using their celebrity status for things like making film clips and public appearances urging Americans to buy war bonds.
Interestingly, John Wayne, who during and after the war starred in many war movies as a heroic fighting man, was classified 3-A by his draft board on the request of his film studio. A 3-A classification amounted to a draft deferral during that war, and he never served in any branch of the military.
For those of you who’ve never seen Bareback Mountin’, I can tell you that Heath Ledger gives the best depiction of a real cowboy (he starts out with sheep, later moving to steers) I have seen in years. Jake Gyllenhal, on the other hand, looked and acted like the grand marshal of a gay pride parade.