Because the movies are a by-product of modern technology, it’s understandable that significant changes in the medium are presumed to be technological. Sound, color, and digital recording are the usual suspects for having caused cataclysmic upheaval.

But on the evidence, sound—supposedly a bombshell innovation that littered theaters with films in which neither camera nor actors moved for fear of getting out of microphone range—was barely a speed-bump. Two of the most active early sound films, Applause and Hallelujah!, date from 1929. The former (with Helen Morgan as a fading vaudeville singer) is astonishingly mobile, not just for its time but in the entire interwar period. Its director, Rouben Mamoulian, was known for sweeping movement in such productions as the original dramatization of DuBose Heyward’s Porgy. In his first movie, Mamoulian uses the camera and editing to choreograph the movie’s viewers as he choreographed the large ensembles of Porgy (and, later, Porgy and Bess, Oklahoma!, and Carousel) on stage. Nothing new in that per se, and that is my point.

Color and videography were even less consequential than sound. (By the way, Mamoulian directed the first full-color feature, Becky Sharp, a reduction of Thackeray’s Vanity Fair that shows he’d lost most of his dazzling movie chops in the six years since Applause.)

No, the biggest change in the movies wasn’t caused by technology. It was caused by history, and it consisted not of how movies were made but of what and who were in them. World War II was its historical cause, and real-world settings, as opposed to movie-studio sets, and real people, as opposed to professional performers, were its essential contents.

Roberto Rossellini flirted with those ingredients in his first feature, the Fascist propaganda piece La nave blanca (1941), by using an entirely nonprofessional cast. For his first postwar feature and still most famous film, Roma città aperta (1945; best-known in America as Open City), all the exterior scenes were shot on the streets of Rome—entirely recognizably and coherently, not, as in most on-location movies nowadays, by changing neighborhood every time the camera turns a corner (e.g., in the trashy Harrison Ford vehicle, The Fugitive, 1993).

Since the facilities of Italy’s film industry were locked down under the American occupation, Open City’s documentary realism was the child of necessity; so, too, perhaps, the use of non-actors in supporting roles. (Open City’s principals, a priest and a young Catholic widow affianced to a Communist partisan leader, were played by established stars required to perform against type, comic actor Aldo Fabrizi and cabaret comedienne Anna Magnani). Its reception—it was a worldwide success—encouraged Rossellini to combine real-world people and settings in its two thematic sequels, Paisan (1946) and Germany, Year Zero (1948), and deliberately introduce a lesser element of big-change filmmaking, improvisation. Those films, the first a set of six vignettes about the growth of cooperation between Italians and invading American GIs, the second about a boy struggling to live amidst the desperation and amorality of ruined, defeated Berlin, opened up a little-explored field of creativity for the movies with their dramatic—not rhetorical—statements of hope and despair in the wake of war. The obvious reality of their settings, the unstudied naturalism of their players (except when speaking clumsily written dialogue), and the unpredictability of their developments give them a grave truthfulness that it is all but impossible for conventionally made movies to duplicate.

I’d like to say that Rossellini’s lead was followed by a multitude of emulative successes, but that isn’t so. In Italy, what was later called the neorealist movement produced some films very nearly as impressive by using non-actors and real settings. The best of those, Vittorio de Sica’s Bicycle Thieves (1949), is very great in its imagery and performances yet vitiated somewhat by Marxist sociological presumption. In France—after the war—Robert Bresson made career-long habits of casting non-actors and shooting on location, from his third film, Journal d’un curé de campagne (1951), to his last, L’Argent (1983); see, especially, Au Hasard Balthasar (1966) and Mouchette (1967).

Much later, Iranian Abbas Kiarostami used all three elements I’ve said are involved the big change—nonprofessional casts, authentic locations, and improvisation—in Where Is the Friend’s Home (1987), Close-Up (1990), and Life, and Nothing More (1991), features as accomplished and engrossing as Rossellini’s and Bresson’s classics. Kiarostami’s younger colleague, Jafar Panahi, added another element to the brew in Offside (2006), when he shot it during the very event—a World Cup qualifying match in Tehran—that is its dramatic raison d’être (it’s about girls trying to crash the forbidden-to-women game). Panahi’s The Circle (2000) and Crimson Gold (2003) honorably demonstrate that the procedures Rossellini pioneered still yield exceptional results. Incidentally, all three of Panahi’s works I’ve mentioned were banned in Iran before release. On December 20, 2010, Panahi was imprisoned (in fact, placed under house arrest) for six years and forbidden to make movies for 20 years. He’s made two since, This Is Not a Film (2011) and Closed Curtain (2013), each technically restricted by having to be made secretly.

Did what I’m calling the big change register at all in American movies? Well, location shooting blossomed after the war, at first to lend documentary verisimilitude to film noir and police procedurals, and improvisation by actors caught on in the late 1960’s. But no, not really. The only thoroughgoing example I know of is The Exiles (1961) a micro-budget independent feature about young Indians who’ve left the rez to live and work in Los Angeles. Fortunately, it’s a very good example, though virtually all the dialogue and ambient sound was dubbed.

Yet there are traces, I’ve discovered, just where you’d expect them. Some of Hollywood’s top directors spent the war in uniform, filming around and during combat. Navy Captain John Ford’s first post-war feature, They Were Expendable (1945), based on the exploits of Motor Torpedo Boat Squadron Three at the outbreak of the war in the Philippines, sometimes has an openness very much like that of the big change movies I’ve discussed; you can’t tell just what’s going on or what will happen next. Ford knew from recent experience what that was like, and in the scenes in which men have to scramble to boats or off a field, he evokes its keyed-up uncertainty from the viewer by how he uses best-available-substitute locations. Ford said he disliked They Were Expendable. I consider it one of his best.

Army Air Force Major William Wyler’s first back-home feature was The Best Years of Our Lives (1946), about the rocky homecomings of three AAF veterans to their mutual hometown. While the film’s sanitizing and schmaltz try one’s patience nowadays, one element of it remains unassailably right. Among the three principals is a disabled seaman. To play him, Wyler cast non-actor Harold Russell, who’d lost his hands while making an AAF training film. If at first Russell seems bland, very soon the contrasts embodied by his professional-actor colleagues—Fredric March, a bundle of actor-ish tics, moues, and calculation, and Dana Andrews, quite a bit better than March but obviously artificially restrained—point up Russell’s granitic authenticity, so much like that of his peers in Rossellini’s, Bresson’s, Kiarostami’s, and Panahi’s best work.