In his 2005 horror movie “The Descent,” writer-director Neil Marshall served up a tale of a bunch of well-muscled modern women being picked off by flesh-eating creatures as they climbed through an Appalachian cave. In his new picture, set in 117 A.D., he focuses on a ragtag group of well-muscled Roman soldiers being picked off by savage, axe-wielding Picts as they try to escape after their legion has been ambushed in northern Britain. One can detect a pattern here.

The historical background to “Centurion” has to do with the Roman invasion of the British Isles that began under the emperor Claudius in the first century and slowly pushed northward over the next decades. By the early second century the advance had largely stalled, but the Romans persisted until Emperor Hadrian declared a halt and tried to defend against attacks by building his famous wall. Marshall’s film deals with the last Roman attempt to move into what is now Scotland, a disastrous expedition in which thousands of legionaries perished.

Marshall bases his script on the old, now largely discredited, legend about the Roman Ninth Legion that supposedly marched northward from the Roman frontier, never to be heard of again. (In fact, the most recent evidence is that the legion was transferred back to the continent, and later to the east.) His highly speculative account—solidly realized in purely visual terms by production designer Simon Bowles, art directors Jason Knox-Johnston and Andy Thomson, set decorator Zoe Smith and costume designer Keith Madden—begins with the heroic centurion Quintus Dias (Michael Fassbender)—whose father, we’re eventually informed, had been a gladiator who won his freedom—manning a frontier garrison that’s overtaken by the Pict leader Gorlacon (Ulrich Thomsen). He’s taken prisoner but escapes, making his way back to the headquarters of the ninth legion commanded by the amusingly named Titus Virilus (Dominic West). Virilus has been ordered by the governor, Agricola (Paul Freeman), to move his men north; a mute Pict woman, Etain (Olga Kurylenko), has turned informant and will lead the soldiers to Gorlacon’s lair, and the general decides to take Quintus along. Of course, Etain turns out to be a plant who takes the Romans into a Teutoberg Forest-type trap. Virtually the entire troop is slaughtered, and Virilus taken captive.

A few stragglers survive, though: Quintus; Bothos (David Morrisey), a hearty fighter; Brick (Liam Cunningham), who’s on the verge of retirement after long service; the Greek Leonidas (Dimitri Leonidas), an expert marksman with sling; a cook from the Far East named Tarak (Riz Ahmed); an African named Macros (Noel Clarke); and cunning Thax (J.J. Field). They try to rescue Virilus, but do not succeed, and he is eventually killed. Since in the process they kill Gorlacon’s son, he pursues them relentlessly, accompanied by the ferocious Etain, who has a personal score to settle herself.

The remainder of “Centurion” details how most of the Romans are stabbed to death, impaled, decapitated, or otherwise done away with by either the Picts or, in one case, wolves—though they manage to take a number of the Celts with them in the process. Marshall likes gore, and he stages the death scenes with plenty of blood, though since cinematographer Sam McCurdy (who composes nice widescreen landscape shots) prefers a subdued color palette that lessens the visual assault. There are some quiet interludes—conversations among the men that reveal something of their histories, and especially a sequence during which the band is sheltered by a Pict woman (Imogen Poots) who’s been exiled from the tribe. But hand-to-hand mayhem is the dominant element. And the cast contribute highly energetic performances, though his role requires Fassbender to brood (and narrate) quite a bit, in contrast to the other characters, who are a more straightforwardly extroverted lot.

The comparison to modern imperialist fiascoes in which apparently invincible forces have been stymied by guerilla tactics is apparent throughout “Centurion.” But it’s brought home with sledgehammer weight in the final reel, when Hadrian not only decides to retrench by building his wall but one of the survivors is killed by what would today be called “friendly fire,” and a cover-up of the legion’s fate is contrived for political reasons, with serious ramifications for poor Quintus. (It’s a pure case of cinematic serendipity that the picture is being released at roughly the same moment as “The Tillman Story.”)

Apart from that, however, despite its attempts at authenticity not only in the accoutrements of dress and weaponry but in speech (some of the Picts’ dialogue is delivered in Gaelic, with subtitles) the movie is really little more than a boys’ adventure tale done in a style more gruesome than most. “Centurion” isn’t as ridiculous as, say, “Pathfinder,” but in the end it’s too intense and nasty to be sheer dumb fun, and too silly and formulaic to be taken for a serious historical epic.