The first, the Oscar-nominated Report from the Aleutians, was released in 1943 and is "a cinematic record of US military operations on the Aleutian Island of Adak to retake Japanese-occupied Kiska." It's available HERE.
The second, The Battle of San Pietro, was released in 1945 and "gives an account of the nine month battle in the area of San Pietro, Italy." (Well, "released" might not be quite the right word, since the Army realized that its harrowing bluntness rendered it essentially useless as a propagandic tool and were less than enthusiastic in their support.) It's available HERE.
The third (and best and hardest to watch) is Let There Be Light. Made in 1946, it "follows 75 U.S. soldiers who sustained debilitating emotional trauma and depression. A series of scenes chronicle their entry into a psychiatric hospital, their treatment and eventual recovery." It's a tough and valuable film, but its subject matter is so demoralizing that was banned by the Army for some 30+ years before finally being released in December, 1980. It's available online now, though, courtesy of the U.S. Army. And it's also available via Netflix, HERE.