Scripter-helmer Christian Carion, whose commercially successful debut "The Girl From Paris" revolved around only two characters, avoids the sophomore slump with flying colors as he smoothly juggles three different cultures -- plus the weight of history -- in a period drama marbled with humor, bold gestures and bittersweet consequences.

Intelligently allowing for the possibility that some filmgoers might not be aware that the Brits and the French were allied against the Germans when war broke out in August 1914, pic begins with three schoolchildren in three classrooms each reciting a nationalistic poem about the patriotic need to obliterate their country's chosen enemy.

Narrative's major characters are then introduced. Anglican priest Palmer (Gary Lewis) observes in dismay as brothers Jonathan (Steven Robertson) and William (Robin Laing) burst with excitement over the fact that they'll be leaving their Scottish village for military training in Glasgow.

Meanwhile, Danish soprano Anna Sorensen (Diane Kruger) watches from the stage of the Berlin Opera as her lover, famed tenor Nikolaus Sprink's (Benno Furmann) entrance is interrupted by a soldier with a message from Kaiser Wilhelm announcing to the audience that Germany is at war.

With no other indicators but a change of language and season, story proceeds to its central location: the freezing front in France. Career French soldier, Lt. Audebert (Guillaume Canet) is sick to his stomach before leading his men on a charge against the Germans in the trench just a few hundred feet opposite.

Unaware the conflict would slog on for four years, Audebert tells his men if they perform well, they can all be home for Christmas in a week. Joining them in battle are members of a Scottish regiment led by Gordon (Alex Ferns).

The Germans are under the command of Lt. Horstmayer (Daniel Bruhl), a smart disciplinarian who speaks both French and English, for reasons that add a late-arriving punch to his character's professional dilemma. A modest barber named Ponchel (Dany Boon) who is Audebert's aide-de-camp, fellow soldier Gueusselin (Lucas Belvaux) and a French General (Bernard Le Coq) round out the principal cast.

Enterprising Anna has wrangled a trip to the German command post to give a Christmas Eve recital. She has a pass from the Kaiser himself and plans to be reunited to sing with Sprink, who is serving nearby under Horstmayer.

The horrors of the war thus far have changed Sprink, who is thrilled to see his true love, but feels his place is back with his fellow rank-and-file soldiers. Thanks to the acoustics of the compact battlefield, on the moonlit night of the 24th, the German tenor and some Scots with bagpipes end up making beautiful music together from their separate protective outposts.

The three officers call a truce, which would ordinarily consist of a cease-fire with all three nationalities staying put in their respective trenches. But one thing leads to another and mortal adversaries are soon fraternizing up a storm. They share champagne, cigarettes and chocolate, hand around photos of wives and girlfriends and communicate as best they can.

The night grows increasingly memorable and turns into a Christmas day as solemn as it is ironic. Where does holiday spirit end and high treason begin?

Because pic is set in an era when codes of honor were clear among the colonial powers, decisions that break the rules carry instant gravitas. The spirit of complicity among adversaries elegantly conveys the oft-explored assertion that war is not only hell but also bottomlessly idiotic.

"A Very Long Engagement" set the bar exceedingly high for subsequent pics set in the trenches of WWI, but production design here serves the story every step of the way, with unfussy widescreen lensing in France, Romania, Germany and Scotland. Well-cast thesps are easy to keep straight.

Although a few lines of dialogue veer toward the overly-didactic or self-consciously poetic, potentially clumsy melding of characters and incidents is deft and convincing, with music as a vector of cross-cultural understanding. When the other shoe drops, viewers have been made to identify with all sides to such an extent that three-pronged conclusion can only be devastating.
 
Camera (color, widescreen), Walther Vanden Ende; editor, Andrea Sedlackova; music, Philippe Rombi; Anna Sorensen's singing voice, Nathalie Dessay; Nikolaus Sprink's singing voice, Rolando Villazon; production designer, Jean-Michel Simonet; costume designer, Alison Forbes-Meyler; sound (Dolby), Pierre Mertens, Tyhomas Desjonqueres, Dean Humphreys; assistant director, Philippe Larue; casting, Susie Figgis, Sabine Schroth. Reviewed at Cannes Film Festival (non-competing) May 15, 2005. Running time: 116 MIN.