Christian Carion has crafted a slick but curiously superficial anti-war crowd-pleaser in “Joyeux Noel,” in which troops from three combatant nations–France, Germany and Scotland–take it upon themselves to declare a Christmas Eve truce along their common line of trenches in the first winter of World War I in 1914. Well-meaning and well-mannered, the picture tugs insistently at the heartstrings but fails to set them aflutter; one comes away from it with a feeling akin to that one gets from opening a glossy but bland Hallmark greeting card.

The picture starts by showing us how some soldiers were called off to war in August: two Scottish brothers (Steven Robertson and Robin Laing) are enthusiastic about the adventure, but their priest Father Palmer (Gary Lewis) weeps over the prospect, while German operatic tenor Nikolaus Sprink (Benno Furmann) is whisked away from the stage–and his lover, Danish soprano Anna Sorensen (Diane Kruger)–by the call to arms. The script then switches to the front at the end of December, where the four men face one another in their respective trenches (the priest serving as a medical officer) and we’re introduced to French Lt. Audebert (Guillaume Canet), the son of a martinet general (Bernard Le Coq), who’s depressed at his separation from his wife, who was pregnant when he left for battle and is now behind the German lines. Other new characters introduced are by-the-book German Lt. Horstmayer (Daniel Bruhl) and Audebert’s comic (and sentiment)-relief aide-de-camp Ponchel (Dany Boon), who misses his mother.

The plot kicks in when lovestruck Anna persuades the Crown Prince, ensconced in a French mansion near the front, to summon Nikolaus to the estate to sing a Christmas concert with her for the army brass–after which she returns surreptitiously with him to the trenches to serenade the men there. Their music–and the bagpiping and caroling of the Scots and Frenchmen–cause a thaw on all sides and lead to an informal cease-fire, during which the men exchange (and bury) their dead under the prodding of pacifistic Father Palmer, share drinks and photos and even enjoy a playful game of soccer. They go so far as to warn one another of upcoming artillery assaults and help each other contact love ones. Needless to say, the unauthorized fraternization does not sit well with their respective commanders when it becomes known, and the outcome is dire for many of the men.

One can’t fault Carion for wanting to make a statement about the futility of war and the beauty of turning swords into plowshares, as it were, even if only for a brief moment in time. But one can certainly complain about the manipulative way in which he’s gone about it. Everything in “Joyeux Noel” is overstated for maximum impact, and as a result it seems more and more false as it goes along. The lack of subtlety infects most of the performances, with Lewis and Furmann faring worst, Canet somewhere in the middle and Bruhl trying to underplay but coming across as merely stiff instead. It goes without saying that Kruger is attractive, but her character’s very presence under the circumstances is so far-fetched that she can’t do more than seem airily unreal. The supporting cast do what’s asked of them, but they too come on very strong. Especially detrimental is Ian Richardson, who arrives late in the action for a stentorian cameo as a pro-war Anglican bishop who berates Father Palmer for his lack of patriotism before giving a speech to the departing troops arguing that God is on England’s side. It’s a dreadfully written scene in the first place, but Richardson overplays it so vigorously that the intended irony practically drips from the screen.

“Joyeux Noel” has a lush visual gloss, with Walther Vanden Ende’s camerawork making the primary setting–the trenches and the stretch of no-man’s land between them–look almost beautiful (in the fashion of the superior “A Very Long Engagement”) and bestowing real elegance on the occasional interiors (opera house, French mansion taken over by the German occupiers) that have been fashioned by production designer Jean-Michel Simonet. (From the technical perspective, in fact, the most serious flaw is aural, not visual: the lip-synching by Kruger and Furmann to the vocals by Nathalie Dessay and Rolando Villazon is pretty awful.) But the attractive facade can’t hide the hollowness within. By trying to draw out an emotional response in the most obvious and ham-fisted ways, Carion’s picture becomes more cloying than uplifting.