Steven Spielberg laid claim to the Normandy beach landing, Clint Eastwood owns Iwo Jima, and now, Christopher Nolan has authored the definitive cinematic version of Dunkirk. Unlike those other battles, however, this last was not a conventional victory, but more of a salvaged retreat, as the German offensive forced a massive evacuation of English troops early in World War II. And unlike those other two directors, Nolan is only nominally interested in the human side of the story as he puts his stamp on the heroic rescue operation, offering a bravura virtual-eyewitness account from multiple perspectives — one that fragments and then craftily interweaves events as seen from land, sea and air.

Take away the film’s prismatic structure and this could be a classic war picture for the likes of Lee Marvin or John Wayne. And yet, there’s no question that the star here is Nolan himself, whose attention-grabbing approach alternates among three strands, chronological but not concurrent, while withholding until quite late the intricate way they all fit together. Though the subject matter is leagues (and decades) removed from the likes of “Inception” and “The Dark Knight,” the result is so clearly “a Christopher Nolan film” — from its immersive, full-body suspense to the sophisticated way he manipulates time and space — that his fans will eagerly follow en masse to witness the achievement. And what an achievement it is!

From the opening scene, “Dunkirk” places us in a state of jeopardy as German sharpshooters pick off a group of British soldiers just yards from the embattled beachhead. Not that things are any safer on the other side of the French-defended barricade. “We surround you,” reads an air-dropped leaflet that accurately represents the Allies’ ever-shrinking position. Backed against the sea, what remains of the British Expeditionary Force can practically see their homeland a mere 26 miles away, but are vulnerable to attacks from the air.

The first fly-by bombing catches us just as much off-guard as it does Tommy (Fionn Whitehead), thin, handsome and hardly more than a child. His dash to the beach could be a game, if the gunshots that fell his comrades and explode inches from his head weren’t so lethal or so loud (as always with Nolan, sound design dramatically heightens the intensity of the experience, which already feels extraordinary given his use of massive-scale Imax cameras).

Driven by a mix of naïveté and survival instinct, Tommy makes an ideal guide through the week-long ordeal, allowing us to experience the strange, almost random way that cowardice blossoms into courage on the battlefield. His storyline, labeled “The Mole” (possibly a play on words, seeing as how it’s set primarily on Dunkirk’s pier-like projection, or mole, but also introduces a somewhat unnecessary subplot involving a non-British infiltrator, or mole), is the most audacious: It features hardly any dialogue, relying instead on our ability to adapt to the unrelentingly harrowing situation, as when Tommy and another low-ranking soldier (Aneurin Barnard) grab a stretcher and use the injured man to board a hospital ship, only to be ordered off moments before it sinks.

No fewer than four British ships go down in “Dunkirk” — not counting the one from which Cillian Murphy’s nameless “shivering soldier” is rescued — and each capsizes alarmingly quickly. This isn’t “Titanic,” in which miniature melodramas had time to unfold as the boat slowly sank, either. Whereas air battles are drawn out and repeated for effect, Nolan and editor Lee Smith compress the doomed-boat scenes for ruthless efficiency, turning the water into a place of high-stakes peril.

While big military ships make massive targets for German bombers and U-boat attacks, Dunkirk’s rough waves and shallow coastline demanded a different approach, and so Operation Dynamo was born: an all-hands call to civilian sailors, asking that they steer any vessel they can, from fishing trawlers to pleasure yachts, across the English Channel to rescue as many of the stranded soldiers as possible. Labeled “The Sea,” this segment feels more traditional, emotionally manipulative enough to match the almost-corny 1940s British propaganda film in this year’s “Their Finest.” (Even in Imax, in which most of the movie fills the massive, nearly-square aspect ratio, this portion is presented in a relatively constrained 2.40:1 format — the same dimensions to which the entire film will be cropped in traditional theaters.)

During this sea-rescue segment, the characters are familiar archetypes, from duty-bound captain Mr. Dawson (Mark Rylance) to determined teenage tagalong George (Barry Keoghan), and their predictable behavior is elevated by the actors’ fine performances. Rylance in particular speaks volumes even when saying very little, and several of the movie’s most poignant moments are conveyed almost entirely without words, via his expressions alone — as when Dawson realizes the likely death that awaits them just beyond the horizon.

Dunkirk’s beaches represent a special kind of hell in the film, a danger zone where the British are frightfully exposed to attacks from above — and where fate, in all its grim absurdity, forces a few of the characters to return multiple times. Just when the soldiers think they’ve escaped, the tide pulls them back in.

Though much of the Royal Air Force was ordered not to engage, a third strand called “The Air” focuses on two Spitfire pilots (Tom Hardy and Jack Lowden) determined to protect, as best they can, the rescue vessels from airborne German attack. Hilariously enough, the role finds Hardy once again in Bane mode, his mouth covered and his dialogue all but inaudible — and yet, the heroism shows through his actions and the determined glint in his eyes.

Both Murphy and Hardy have worked with Nolan before (each as Batman villains), but he uses them in character-actor mode here, treating these marquee talents as equals among a cast of newcomers (including Harry Styles, looking every bit the 1940s matinee idol). Playing the highest-ranking Navy officer on the beach, Kenneth Branagh provides the film’s only star performance, and even then, it all comes down to a meaningful salute delivered in “Dunkirk’s” final minutes.

By this point in the film, Nolan has tied the three storylines together. While unnecessarily confusing at times (and not especially satisfying as a puzzle — at least not in the way the ingenious backward-logic of “Memento” was back in the day), by splintering these three storylines, the director allows us to experience the Dunkirk evacuation from multiple perspectives. In his extensive pre-production research, Nolan pored over survivors’ firsthand accounts and inevitably found inconsistencies among them — a phenomenon he ingeniously incorporates into his screenplay. In “Dunkirk,” subjectivity is not merely a tool for in-the-moment suspense, but also for suggesting the innumerable different ways people both lived and remembered the week’s events: One moment, a Spitfire pilot might be swooping in to save a Navy ship, and the next, he’s the one in need of rescuing as his seatbelt jams and his cockpit fills with water.

And yet, Nolan never once privileges the German p.o.v. (a bold departure from most war movies, including “Tora! Tora! Tora!,” which showed both sides, or Michael Bay’s “Pearl Harbor,” which famously offered a Japanese bomb’s-eye-view of the attack). Nolan’s goal is to give an exclusively British account of events, zeroing in on how it must have felt to the everyday heroes who lived it, as opposed to the leaders calling the shots. When Winston Churchill is finally heard, his words are being read aloud from the pages of a newspaper by an ordinary soldier, rather than delivered by the prime minister himself.

And in that nuance is the great accomplishment of Nolan’s feat: On one hand, he has delivered all the spectacle of a big-screen tentpole, ratcheting up both the tension and heroism through his intricate and occasionally overwhelming sound design, which blends a nearly omnipresent ticking stopwatch with Hans Zimmer’s bombastic score — not so much music as atmospheric noise, so bassy you can feel it rattling your vertebrae. But at the same time, he’s found a way to harness that technique in service of a kind of heightened reality, one that feels more immersive and immediate than whatever concerns we check at the door when entering the cinema. This is what audiences want from a Nolan movie, of course, as a master of the fantastic leaves his mark on historical events for the first time.