A little poem by A.E. Housman about the dead of World War I still has the power to make shivers run up the spine.

Here dead we lie
Because we did not choose
To live and shame the land
From which we sprung.

Life, to be sure,
Is nothing much to lose,
But young men think it is,
And we were young.

The pathos he evokes depends utterly, it seems to me, on the “Because … ” clause in the first stanza.

In other words, there was a reason why the young men died. Negatively, it was called shame; positively, honor. The sadness of their loss is actually greater because Housman accepts this reason without comment or criticism.

The film “Joyeux Noel” – Christian Carion’s often moving cinematic account of the true story of the 1914 Christmas truce on the Western Front – is similar to most portrayals of this war in ignoring or disparaging the reason for it that Housman presents so dispassionately.

On this view, our sympathy with the victims of the war should be increased by the assumption that the slaughter was “senseless” – for nothing. The filmmakers present World War I as the product of wicked or stupid leaders who somehow successfully brainwashed their people into thinking of the enemy as subhuman and deserving of merciless extermination.

Whether or not this is a tenable view of the actual war’s origins and history I leave to others to decide. As a matter of artistic and dramatic judgment in a film like this one, this view is a serious mistake. It forces us to suppose that those who died were fools, blind to the meaninglessness of their sacrifice. Pity for them must be mixed with contempt.

Because at the time both sides tried to suppress any information about the truce as prejudicial to military discipline, we don’t know much about how it actually happened, and Mr. Carion’s version is thus mostly fiction. But he arranges events so that the brainwashing theory is presupposed.

He leads off with specimens of the brainwashed in the form of British, French, and German schoolchildren. They recite, as if by rote, patriotic spiels to the effect that one of the other nationalities are devils incarnate.

Cut to the arrival of the news that war is declared. Everyone is happy. “At last something is happening in our lives,” says a young Scot called William (Robin Laing), who will soon be dead. His brother, Jonathan (Steven Robertson), refuses to acknowledge William’s death in a letter to his mother. Palmer (Gary Lewis), a priest from his hometown who is serving as a medic with the regiment, tries to console him.

On the German side, Private Sprink (Benno Furmann), an opera singer in civilian life, is summoned by Crown Prince Friedrich-Wilhelm (Thomas Schmauser) to a chateau behind the lines, where he and his Danish fiancee, Anna Sorensen (Diane Kruger), are invited there to sing (with the voices of Rolando Villazon and Natalie Dessay) for the top brass. Rather improbably, Anna persuades Sprink to take her back to the front with him on Christmas Eve.

In the French trenches, Lieutenant Audebert (Guillaume Canet) is frantic with worry about his wife, who is behind the German lines in northeastern France. She had a difficult pregnancy in the summer of 1914 and must have given birth by now, but he has had no word from her in months. His father (Bernard Le Coq), a general, is trying to get him sent to the rear, out of the worst of the fighting.

On Christmas Eve, the sound of the Scots playing a mournful tune on their bagpipes in the trench opposite inspires Sprink to sing “Silent Night.” Soon the bagpipers are joining in, and Sprink seizes a small Christmas tree, holding it before him as he steps into no-man’s land. In no time, the French and the Scots are out of their trenches, as well.

The junior officers in charge on this narrow section of the front, Audebert for the French, Gordon (Alex Ferns) for the Scots, and Horstmayer (Daniel Bruhl) for the Germans, meet to agree on a truce just for Christmas, but the fraternization among their men looks as if it is getting out of control. Palmer says Mass for the men of both sides, and they share food and drink and have a game of soccer.

The next day, no one wants to be the first to end the truce. The Germans inform the Allies that their trenches are about to be shelled and invite them to shelter with them. The Allies then return the favor.

Eventually, some more senior officers turn up and put a stop to it all. There are too many to court-martial, but the Scottish regiment is disbanded and the men reassigned while the French are sent to Verdun and the Germans to the Eastern Front.

All are reproved for their dereliction of duty, but remain stubbornly attached to the idea that the truce was a good idea. Just for a moment, they have awakened from their brainwashed torpor and recognized the other side as human. Afterward they can never quite forget it again.

Meanwhile, presumably, all the rest of the numbskulls on the Western Front went on killing each other, zombie-like, for the next four years. Sorry, but I just don’t buy it. Mr. Carion’s movie is an emotionally powerful glimpse of the interruption of war’s horror by an outbreak of humanity, but I think it would be much more powerful if it had more sympathy for the reason the warriors were there in the first place.