Sam Mendes’ “1917” is a gripping and quite entertaining Tommy’s-eye-view of The Great War” as seen from the trenches of France.

Mendes (“Jarhead,” “Skyfall”) didn’t get his tribute to the men and their sacrifice in World War I out in time to coincide with commemorations for the end of that conflict. But he’s cooked up an immersive, heroic tale that humanizes a conflict canonized for its faceless slaughter and waste, a “Lost Generation” grimly depleted on the Fields of Flanders.

The story could not be simpler — two British soldiers (nicknamed “Tommies”) are sent across nine miles of No Man’s Land and enemy occupied territory to halt an attack that will only get their fellow soldiers slaughtered. The attack’s at dawn tomorrow, so you’d better get cracking, lads (George MacKay, Dean-Charles Chapman).

Lance Corporal Black (Chapman, of “Game of Thrones”) is determined to save the “Second Devons” (Devonshire Regiment), at least partly because his own brother is a lieutenant serving with them. The general (Colin Firth) picked him for this mission because he’s good with maps, and he’ll be extra motivated.

Lance Corporal Schofield (MacKay, of “Pride” and “Captain Fantastic”) was just unlucky enough to be Blake’s chum, the one he picked to accompany him. Schofield didn’t survive the bloody horrors of The Somme to get killed on some suicidal sprint to hand deliver a note. Medals, ribbons and “a mention in the dispatches” are no enticement to him.

But radios were not yet in common use on the field, and “Gerry’s cut our telephone lines,” so there’s nothing for it.

Thus begins a grim odyssey through the World War I experience — the green flowering of spring unfolding under the rotting corpses of men, horses and dogs beset by the flies of April. Mud and snipers, a wrecked tank, miles upon miles of barbed wire, ruined towns, the fascinating over-engineering of German trenches (abandoned in “a planned withdrawal”), booby-traps, dogfighting biplanes rat-a-tatting above — Blake and Schofield are solitary souls on a quest in the middle of the maelstrom of war.

The camera clings to these two as they stumble and grope, under overcast skies or in the dark of dugouts and tunnels, through the quiet hell of a battlefield half-abandoned but sure to be full of sound and fury again, any minute now. Mendes uses “the long take,” a nearly seamless series of scenes unfolding in (for the most part) real time to build suspense and empathy for our two over-matched heroes.

Because this script is hellbent on throwing every peril The Great War was infamous for at them over the course of two hours.

Mendes and his “Penny Dreadful” co-writer hurl the duo into corpse-covered shell-craters and spooky tunnels. Death comes from afar — artillery and snipers — and very close. Rifles and bayonets and bare hands are what it takes to stay alive. Death comes from above — airplanes — and below (a raging river).

Of course there’s a mademoiselle in distress (Claire Duburcq) to be stumbled over, amid the cream of British character actors who play sergeants and commissioned officers (Benedict Cumberbatch, Daniel Mays, Adrian Scarborough, Mark Strong) who pass by.

Of course the foreshadowing is obvious, but not heavy-handed.

It’s meant to be immersive, a “Dunkirk” of the first World War. And if it isn’t on a par with that modern classic, you can blame the slack pacing, the heaping helpings of melodrama in the tale Mendes and Krysty Wilson-Cairns cooked up. All these obstacles to overcome, and yet so many longueurs — pauses while the soldiers on this desperate, dangerous time-sensitive mission stop to shake their heads at the waste or consider the Last Milk Cow on the Western Front. Our heroes listen to a soldier singing “When I Cross Over Jordan” and take time to recite a poem — Edward Lear’s “The Jumbles” (“In a Sieve they went to sea; In spite of all their friends could say…”).

“1917” loses its urgency just enough to make you notice and wonder “What are these two doing? Get BACK to the MISSION!”

Mendes gets the blasted landscape of No Man’s Land, the trenches, the kit each soldier carries with him right. The rapidly shifting shadows created by a descending flare make for a striking scene.

But he fritters away some of the tension and the drive of the narrative when he loses the crouching/ducking fear and paranoia that had to become instinct if you were to have any hope of surviving the war.

The “long take” has long been enshrined as a sort of cinematic rite of passage, something filmmakers indulge in mainly, one suspects, to impress the faithful — hardcore film buffs.

Orson Welles had a hand in elevating these long unedited shots that rely on camera blocking, staging, pre-planning and actors who can remember a lot of choreography to go with their lines. “Touch of Evil” opens with the most famous “long take” in cinema history.

Properly applied, long stretches without a perspective-changing interruption (edit) can build tension, when you’re not distracted and impressed by how many characters and how much ground Robert Altman’s opening to “The Player” has squeezed in. We are conditioned to cuts, and the mind misses them when they’re not there. Suspense builds as we expect something momentous coming at the end of the build-up a long take entails.

Hitchcock took this to its logical extreme with “Rope,” a 1948 thriller whose stagebound origins allowed him to “indulge” in making a film of ten long takes — with only the limitations of a reel of celluloid loaded into the camera determining how many edits the picture would have.

But Hitchcock admitted that “Rope” was just “a stunt.” Editing is the essence of cinema, “the lynchpin of worthwhile filmmaking,” as Sir Alfred put it. Cuts quicken the pace and raise the heart-rate, refocus our attention, zooming in, heightening suspense and connecting us with the characters with emotional close-ups.

You want to see a movie with “no cuts” and nothing but long takes? Hunt down “Russian Ark.” Yes, like “Rope,” that was a stunt. Like “Rope,” it’s “cool” but dull.

So no, the long takes don’t transform “1917” into the cinema event of 2019.

It’s still entertaining, a polished period piece and solid combat film, even if its story leans entirely too heavily on the hoary conventions of the Victorian/Edwardian melodramas that every Briton fighting in it would have recognized, way back then.

MPAA Rating: Rated R for violence, some disturbing images, and language

Cast: George MacKay, Dean-Charles Chapman, Daniel Mays, Mark Strong, Richard Madden, Claire Duburcq, Colin Firth and Benedict Cumberbatch

Credits: Directed by Sam Mendes, script by Sam Mendes and Krysty Wilson-Cairns. A Universal/Dreamworks release.

Running time: 1:59