By the time I got to page four, all my choices were already posted...sniff...
However, no one mentioned
Zepellin starring George Peppard. Corny in places, but great footage anyway.
Also a Rock Hudson comedy-romance with him as an American WWI pilot,
Darling Lily. Full of stars, and surprisingly good combat scenes.You have to love the guy who always flies drunk.
Not sure about the time frame, but I seem to remember an old black-and-white about Browning and the BAR.
Funny the stuff that didn't get into the movies, like the raids on Zeebrugge or Ostende. There is a book called
Sixty Minutes For St. George that would be a terrific movie. Also a book called The Lion At Sea, same thing.
Lots of good stuff that would make great WWI movies, but no studio takers, I guess. Too bad. An almost forgotten era for most people.