Alternating between gorgeous imagery and scenes of devastating brutality, “Simon, an English Legionnaire” details the coming-of-age of a young Englishman during the French-Algerian conflict. Though engagingly told and handsomely mounted, this fact-based pic would be a tough sell, as even heavily marketed and higher-concept period war films (“Hart’s War,” “Windtalkers,” “The Four Feathers”) have struggled of late to find an audience.

When his girlfriend Jennifer (Kate Maberly) rejects him, the dispirited Simon Murray (Paul Fox) opts for a radical life change to take him far away from his sorrows. After signing on to the French Foreign Legion for a five-year stint, Simon is posted in Algeria. At the onset of his military training, he discovers the Legion falls short of the romantic ideal he had nurtured from the movies; it is instead a harsh and unrelenting world of stringent discipline in which superiors mete out blistering punishments for even the tiniest infractions.

Simon befriends some of his fellow recruits, including the fiery, intelligent Frenchman Dupont (Tom Hardy) and Spaniards Valdes (Aitor Merino) and Rodriguez (Javier Alcina). Despite their initial trepidation, the men gradually transform themselves into a steely fighting force. But their allegiance is threatened when one member of their troop goes AWOL and suffers unspeakably violent consequences.

An equally unsettling sequence ensues when Simon loses the camera with which he had been photographing dead rebels. Required to provide proof of military kills, Simon and a fellow recruit are obliged to decapitate a corpse and bring back the head of the deceased.

Once graduated to full Legionnaires, the men enjoy life on the town. Simon falls for the lovely Algerian-born French girl Nicole (Felicite du Jeu), a staunch supporter of the “Pied Noir” opinion that Algeria should remain in French hands. At the same time, Simon begins to empathize with the opposite perspective when he witnesses how shabbily the Arabs are treated in their homeland. As the conflict escalates and President De Gaulle vacillates on the issue of Algerian independence, Simon’s own loyalty is tested.