Although it may not qualify, exactly, as a “World War I movie”, the 1926 film, ‘Tell it to the Marines’, starring Lon Chaney (in his only starring role where he didn’t wear sophisticated makeup), is truly a great movie. I got to watch it on TCM last summer and was floored.
By the way, Lon Chaney was a huge star a real long time ago but is, hands down, one of the greatest actors of all time. He pioneered the art of makeup and starred in many of the most enduring movies of the era (’The Phantom of the Opera’ and ‘The Hunchback of Notre Dame’, for example). He was a very private family man who once proclaimed, “Between movies, there is no Lon Chaney.” He built a cabin high in the Sierra Nevada wilderness as a retreat. A read of his Wiki bio is highly recommended if you are not familiar with the great Lon Chaney. He died young, in 1930, at age 47.
(Yes, Chaney’s son, Lon Chaney, Jr. later found fame as ‘The Wolfman’, Larry Talbot.)
Chaney's character was the prototype for all the "tough marine seargeants" that came after. I understand that he was made an honorary Marine for his performance.