One reviewer commented that he didn't know how this film ever got released during World War II. It almost didn't.
First, you need to know that Hollywood actors, directors and producers were heavily recruited by the War and Navy Departments (the Defense Dept. is a post war innovation). These celebrities got to know a lot of the senior military personnel through their activities in Stage Door Canteens, the USO, recruiting and bond drives. Few were closer to the military top brass than Orson Welles, a close friend of Houston's.
Welles told this story on, I believe, a Dick Cavett Show in the late 1960s or very early 1970s. I repeat it as I remember it.
According to Welles the War Department censors did not want San Pietro released. They felt that the film was too graphic and that it might have an adverse effect on support for the war. Through Welles' personal friendship with General George C. Marshall he and Houston arranged a private screening at the Pentagon for Marshall, his staff and the censors. Following the screening Gen. Marshall stood up and ordered that the film be released. He said that it was an accurate depiction and that war was horrible. He felt that the American people needed to know that horror lest they romanticize war and become fond of a monstrous act of inhumanity.
So San Pietro was released. If Welles exaggerated his role, I can't say. Certainly Houston didn't contradict him. If I have misremembered the tale in some particular, it does not change the fact that San Pietro owed its release to the intervention of Marshall.
Even today San Pietro is worth seeing. As has already been suggested, it is a good complement to Lewis Milestone's All Quiet on the Western Front. I would suggest that it also ranks with two other great movies whose subject is World War I. Those movies are Jean Renoir's Grand Illusion and Stanley Kubrick's Paths of Glory. And, although it doesn't quiet rank with the three films already mentioned, Philippe de Broca's King of Hearts belongs in the insanity of war film festival we seem to be constructing here. Finally, I would point out that earlier wars are often stand ins for the more recent one as in M.A.S.H. Korea stood in for Vietnam.