Sounds a bit like Sergeant York, except that the hero is an American boxer who rejects violence outside the ring. He gets called up, and, once in the trenches - guess what?
Anyway, the point is that this still shows an FT17 (probably an M1917) so there must be some reasonably authentic battle scenes. The only other still I can find is this group of stock characters, including the customary lumpy-faced big bloke at the back, as seen in most cinematic portrayals of American forces, beginning with the 7th Cavalry. You know the one.
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Acc to IMDB several of the cast are credited as "Tank Crew", which suggests that Tanks feature to some extent in the film. I expect they will be M1917s.
Haven't managed to find this on DVD or anything, although it does appear to have been screened at film festivals, etc.
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"Sometimes things that are not true are included in Wikipedia. While at first glance that may appear like a very great problem for Wikipedia, in reality is it not. In fact, it's a good thing." - Wikipedia.