Dunkirk’s status as an unusual WWII film is an apt one, seeing as the evacuation from the titular French beach doesn’t fit the genre mold.

Not well known by modern American audiences and barely told in cinematic form — beyond the extraordinary long take in Joe Wright’s Atonement and being the basis of the propaganda film-within-the-film of this year’s charming Their Finest — the rescue is an appropriately esoteric choice for the first war experiment by Christopher Nolan, a filmmaker who rarely (if ever) follows “the rules.”

Compact in runtime — it’s Nolan’s first sub-two-hour film in 15 years (Insomnia) — but broad in scope, there’s a consistent sense that with each grand image of actual ships and planes, a massive cast and practical effects, the man in charge is creating exactly what he envisioned.

The British military backed to the English Channel by the Germans, Dunkirk weaves together threads involving a trio of RAF pilots, one of the many civilian sea-crafts tasked with getting the soldiers home safely and the thousands immersed in dire straits on the beach.

If there’s a lead character, it’s a soldier played by newcomer Fionn Whitehead who simply cannot catch a break — nearly to a comical Brad Pitt in World War Z degree, if the predicament didn’t feel so authentic — but not from lack of trying.

The bad luck that follows him from land into the sea conveys the situation’s desperation and growing sense of futility, as well as the British troops’ refusal to give up.

Pop star Harry Styles (whose famous visage doesn’t much detract from the action) to one side, Nolan casts anonymous fresh faces as the soldiers, all of whom do convincing work and are fortified by the director’s past collaborators Tom Hardy and Cillian Murphy and new heavies Kenneth Branagh and Mark Rylance.

Once Dunkirk’s rhythm is established, Nolan nimbly moves between the three potent settings with practically equal interest, tastefully playing with chronology. The sudden dawn of nighttime fairly early on is a tad disorienting, though a cut shortly thereafter to a different perspective of a scene that’s already played out allows his master plan to grow clearer.

Each arc is enthralling in its own particular way, but the edge goes to the one involving Hardy’s pilot, easily the film’s emotional heart. Perhaps encouraged by George Miller in Mad Max: Fury Road, Nolan once more puts his friend in a mask — this time inspiring one of his most reserved performances, yet one that ranks up with his more bombastic turns and could produce waterworks at the film's expertly-staged climax.

Grade: A. Rated PG-13. Now playing at AMC Classic, Biltmore Grande, Carolina Cinemark and Grail Moviehouse

(Photo: Warner Bros.)