How many active American film directors have served in the military? Clint Eastwood, Oliver Stone ... if there are others, they've kept it a pretty good secret. Does it make any difference? The only answer one can take away from Five Came Back, a somewhat choppy but unavoidably fascinating documentary about five major Hollywood directors who, after Pearl Harbor, left house and home and handsome salaries to spend several years in uniform making documentaries for the U.S. war effort, is yes. The effect World War II had on Frank Capra, John Ford, John Huston, George Stevens and William Wyler was profound, changing the nature of the films they made, and this three-part, three-hour Netflix presentation is intimately in tune with its subjects and the work they did.

Mark Harris' popular 2014 book, Five Came Back: A Story of Hollywood and the Second World War, is unquestionably the most absorbing and thorough account of Hollywood's unprecedented and often bumpy relationship with the government in creating and distributing these propaganda films. The advantage the book has over the documentary is its ability to delve deeply into the disputes, delays, compromises and practical challenges involved in making the Hollywood/D.C. collaboration work (which it sometimes didn't), as well as to explore the thoughts and turbulent emotions of the formidable personalities involved.

But the advantage the documentary has over the book is that it's able to show off the films themselves, as well as a good deal of related footage that brings the war, and the filmmakers themselves, to life. Director Laurent Bouzereau, who is best known for his innumerable “making of” documentaries, most notably those about Steven Spielberg films, is right at home with this sort of material and has uncovered a treasure trove of unfamiliar footage of wartime Hollywood.

He's also engaged five leading contemporary directors — Spielberg, Francis Ford Coppola, Lawrence Kasdan, Paul Greengrass and Guillermo del Toro — to bring diverse filmmaking perspectives to the subject. Each modern helmer was assigned one of the five veterans, a ploy that succeeds more often than not by virtue of the professional expertise and personal sympathy brought to bear on what their forerunners went through.

Part One is the patchiest of the threesome, in that Bouzereau has to toss so many balls in the air and try to keep them there. He must properly introduce his stars: Sicilian immigrant (and Mussolini fan) Capra, the populist director of heartfelt comedy/dramas such as It Happened One Night and Mr. Smith Goes to Washington and already the winner of two Oscars; Ford, at 46 the oldest of the bunch when the U.S. entered the war and also a double Oscar winner at a career peak after The Grapes of Wrath and How Green Was My Valley; Huston, the untamed son of prominent actor Walter Huston who has just made the grade in Hollywood with his directorial debut, The Maltese Falcon; Stevens, the taciturn master of smart comedy who had just switched gears with the popular Gunga Din; and Wyler, a German-born Jew brought to Hollywood by a relative, Universal boss Carl Laemmle, and recently risen to great heights with Wuthering Heights and The Little Foxes.

A very strong argument could be made that Harris' book, and thus the film, should actually have been called Six Came Back, based on the unfairly unheralded contributions to the cinematic war effort of another quickly rising European emigre of the moment, Anatole Litvak. The Russian native had already built a formidable career in Europe (Mayerling) before arriving in Hollywood and directing, in 1939, the provocative Confessions of a Nazi Spy, the first Hollywood film to raise an alarm about the soon-to-be enemy threat on native soil. Once in the U.S. Army film unit, Litvak directed the best of the Why We Fight entries, The Battle of Russia (Capra, also listed as director, in fact just supervised), whereupon he went to the Soviet Union to present the film to the Russian general staff, translating as it was shown, and was personally decorated by an approving Stalin. He played a leading role in filming D-Day and directed one of the strongest post-war dramatic films shot in the rubble of Europe, Decision Before Dawn. While Litvak is not as well known as the “five,” he was a formidable figure, a very close friend of Huston and Wyler, and his contributions were on a level that merited far more than the passing mention he receives in both the book and film.

Ford was the first out of the gate with an important documentary, The Battle of Midway, which depicted the first American victory of the war. Of the five contemporary directors on hand to speak about the elders, the British Greengrass somewhat surprisingly seems to have the most intuitive and passionate understanding of his subject, the far more formal and ostentatiously Irish-American Ford. Expanding upon Harris' astute insights into Ford's complicated character, Greengrass shrewdly takes the measure of the man's sometimes devious motivations and methods; here was a director who feigned disdain for the Oscars by never showing up for the ceremonies but was actually “a glory hound.”

Kasdan offers more intellectual and informational perspectives, opening Part Two by posing the question all the enlisted directors faced: “What should these movies be?” Capra, who is mostly assessed by fellow immigrant del Toro, spent most of his time in Washington overseeing the Why We Fight series, which was meant to explain the necessity of the war to the American public, to variable results. But he also conceived a series of war-related cartoons, Hey, Soldier!, which alerted new recruits to the dangers of such hazards as reckless gossip and venereal disease, were sometimes quite raunchy and employed the services of Theodor S. Geisel (the future Dr. Seuss), Chuck Jones, Mel Blanc, Bob Clampett, Frank Tashlin and Munro Leaf.

After making the almost hauntingly uneventful Report From the Aleutians, Huston spent months living the high life in New York City before reporting to Italy once the Allies landed. His San Pietro offers a chilling account of an Allied assault on an enemy-held small town — the camerawork is often unsteady, deaths mount up — but it was, in fact, a staged re-creation enacted several days after the actual events. It was a fiction even Huston himself perpetuated for decades thereafter.

Spoken about with strong feeling by Spielberg, Wyler, who became instantly celebrated in London upon the release of his drama of British wartime resolve, Mrs. Miniver, arguably made the best straight-up combat documentary, The Memphis Belle: The Story of a Flying Fortress, which featured great color footage of B-17s on bombing runs over Germany.

But the big stuff is delivered in Part Three, which opens with Ford and Stevens being assigned by Supreme Allied Commander Eisenhower to film D-Day, which involved hundreds of cameras. Footage of the invasion was on American theater screens within days, but the reactions of the two American directors in charge were telling; after the overwhelming violence of the first day, Ford went on a bender that got him sent back to the U.S., while Stevens persevered. Filming in vivid color, he kept moving with the troops and made a point of documenting everything: the G.I.s' welcomes in small French villages, the Allies' tumultuous welcome in Paris, the surrender of a Nazi general to de Gaulle, which Stevens requested the French general to restage outdoors for better lighting.

After the Battle of the Bulge, Stevens moved on — to Dachau. Assuming it was a normal prison camp, the Allies were entirely unprepared for what they saw — the corpses, the skeletal survivors, the overwhelming proof of extermination on an unimaginable scale. Rather than turning away from the horror, Stevens just kept filming and filming, his mission now changed to that of accumulating evidence for future legal proceedings as well as history. He spared nothing, no matter how awful. One of the two documentaries he put together, Nazi Concentration Camps, was used at the Nuremberg trials.

As Coppola recounts, Huston made one more documentary before hanging up his uniform. Let There Be Light takes a close-up look at returning soldiers suffering from extreme psychological trauma. Gentle, empathetic and astutely modulated, it is by far the most emotionally affecting of any film its director ever made, but it was banned by the Army for 30 years; the film was too honest about the non-physical side effects of battle.

In their own ways, all the filmmakers were changed by their wartime experiences. Least altered, arguably, was Huston, who, once back in Hollywood, got right back to work on a project he had left behind three years earlier, The Treasure of the Sierra Madre. Ford, after making his superb, but commercially disappointing, Pacific war drama They Were Expendable, turned increasingly to the past and, specifically, to the American West for subject matter.

Seeking independence from studio bosses, Capra, Stevens and Wyler formed their own company, Liberty Films, which made exactly one picture, Capra's It's A Wonderful Life. Now widely considered a classic and perhaps its director's best, the costly film received mild reviews and its box-office under-performance dashed the enterprise right out of the gate. For the final stretch of his career, Capra was basically a director for hire.

Stevens was simply numb, unable to stir himself to engagement with any material, least of all comedy, which had been his forte. Eventually, he got back to work, enjoying great success and awards with films that became increasingly heavy and long.

Profoundly depressed upon his return and fearing he'd never work again due to a near-total hearing loss on his final aerial expedition in Europe, Wyler was ultimately the one who made his time in his country's service count onscreen. Spielberg speaks beautifully about The Best Years of Our Lives, Wyler's deeply felt account of three returning war vets, which was shot by another war documentary vet, Gregg Toland. The director remained on top for another two decades.

Along with Five Came Back, Netflix will stream 13 related wartime documentaries beginning March 21. Among those that can be particularly recommended are The Battle of Midway, The Battle of Russia, The Memphis Belle: A Story of a Flying Fortress, The Negro Soldier, San Pietro, Nazi Concentration Camps and Let There Be Light.

With: Steven Spielberg, Francis Ford Coppola, Guillermo del Toro, Paul Greengrass, Lawrence Kasdan
Narrator: Meryl Streep

Director: Laurent Bouzereau
Writer: Mark Harris, based his book
Five Came Back: A Story of Hollywood and the Second World War
Premieres: March 31 (Netflix)