“Dunkirk” is intense to the point of being exhausting. Take the D-Day invasion scene in “Saving Private Ryan,” extend that level of terrified chaos until it’s an entire movie, and you’ll have a feel for this ferocious depiction of the World War II beachfront battle.

Written and directed by Christopher Nolan of “Dark Knight” fame, it’s a cinematic triumph that will awe some viewers and alienate others — for the same basic reasons.

“Dunkirk” intertwines story lines, jumping from one to another, back and forth in time, depicting a moment from various perspectives. The soundtrack is a pounding, bass-driven barrage that mimics the beating of a frightened heart. No character is sacro­sanct; if you bond with one, you run the risk they will be shot, blown up or drowned in the next scene, adding a palpable layer of unease with the awareness that even a marquee star like Kenneth Branagh (playing a navy commander) is as vulnerable as anyone else.

Fans of Hollywood connect-the-dots narratives may be frustrated by the art-house sensibilities on display here. There’s a minimum of dialogue; Nolan tells his story through brutal images and closeups of frightened faces. He doesn’t even give us a traditional protagonist. Rather than a war hero rising to the occasion, the central character is trying to flee the fighting but keeps getting sucked back in.

Nolan provides only the sketchiest explanation of the action, so for those who need a briefing: In 1940, German forces burst through French defenses, pushing the Allies back toward the English Channel. An estimated 400,000 Allied soldiers, the bulk of them British, were bottled up in the seaport of Dunkirk. Then the Germans set out to methodically annihilate them.

The movie opens with a moment of tranquility — savor it; it’s the last one until the closing credits roll. A British squad is casually making its way down a deserted residential street. The soldiers — teenagers, for the most part — stop to drink from a garden hose and pilfer a treat from a candy dish in a window.

Shots break the silence. Some of the young soldiers fall and the rest start running for their lives — something they will be doing for the rest of the movie. (Not until the final moments do we glimpse German soldiers, perhaps because Nolan didn’t want to remind us they were mostly kids themselves.)

Tommy (newcomer Fionn Whitehead) scrambles to safety, but it doesn’t take long to sense it’s a temporary reprieve, as he reaches the beach and sees tens of thousands of troops lined up, waiting to be evacuated.

Realizing that the wounded are getting priority, Tommy and another desperate comrade try to jump the line by pretending to be medics. The gambit fails.

Meantime, a middle-aged Englishman named Dawson (Oscar winner Mark Rylance) is steering his small yacht toward Dunkirk — part of the legendary flotilla of civilian boats that raced across the channel to rescue stranded soldiers. On the way, he plucks from the water the shell-shocked survivor of a torpedo attack who begs him not to continue, warning, “If we go there, we will die.” Dawson stoically replies, “I see your point, son,” then continues toward the black plumes of smoke rising across the water.

The third part of the story takes place in the cockpit of a British Spitfire fighter plane offering air support for the rescue effort. It’s flown by the unflappable Farrier (Tom Hardy, who worked with Nolan in “Inception” and is all but unrecognizable here with his flight mask on). This is the only time Nolan’s script falls victim to cliché; Farrier is warned to save enough fuel to get back to his base in England. The instant he promises he will, everyone in the theater knows he won’t.

Even though the film’s body count easily reaches four figures, Nolan avoids gore. In that sense at least, the PG-13-rated “Dunkirk” is very old-fashioned, recalling the John Wayne ilk of war movies, before special effects dominated filmmaking.

Then again, this movie doesn’t need a lot of blood and guts to drive home its point. Nolan does a magnificent job with his mostly young cast, shooting closeup after closeup of their petrified eyes as German bombs rain down and bullets pierce their fragile sanctuary. This is not a chew-the-scenery kind of movie, but one that’s bursting with feeling. Nolan has delivered a stunning film, both figuratively and literally.