In a brief, quiet interlude during Fury, a group of American soldiers gaze into the sky, where two sets of warplanes head for each other in formation.

It's a beautiful image, which cuts away before the dogfight begins. And it's in stark contrast to what happens on the ground, which doesn't flinch from brutal reality for a second.

Fury is one of those rare war films that offers an unremittingly bleak reminder that war is a dirty, godforsaken business. It's a film about men, even good men, losing touch with their humanity.

It's set in 1945, with the war in Europe almost over as the Allies make their way into Nazi Germany. Hitler has insisted that every German continue to resist, man and woman, soldier and civilian; those who don't are hanged, their bodies left dangling by the road. Exhausted by months of fighting, horror and loss, the Americans have the look of defeat about them, not imminent victory.

Brad Pitt stars as Sergeant Don Collier, battle name "Wardaddy", the commander of a Sherman tank with its own macho nickname. A strong opening depicts the battering that the Shermans have been taking from the heftier Panzers, and the psychological mess that has been inflicted upon the Fury's crew. Though varied in type - the Latino driver, the Bible-bashing gunner, his redneck loader, their educated, authoritative leader - they are united in weariness and hate.

One pities the luckless rookie thrown into their mix. Norman Ellison (Logan Lerman) is a clerk who's only been in the war for a matter of weeks when he's told he's needed as an assistant tank driver. The film's dramatic thrust will be this boy's coming of age as a soldier.

Director David Ayer is a navy veteran who served on a nuclear submarine. His first script was for U-571, a so-so Second World War submarine movie, before he hit pay dirt with corrupt cop movie Training Day. He's since directed the acclaimed End Of Watch, also about LA cops.

Like End Of Watch, Fury attempts to imbue a greater sense of reality into a genre piece. We certainly feel the grime, the claustrophobia of the tank, the visceral horror of what happens when bullets, shells and mines make contact with flesh, the arbitrariness and suddenness of death during war. Some of the action sequences are outstanding in their detail and execution, in particular a dance of death between three Shermans and a Panzer, which is as much about manoeuvre and calculation as might.

Around such physical authenticity, the film shares with Sam Peckinpah's Cross Of Iron a desire to depict the moral cesspit that awaits soldiers beaten down and inured by violence. It's a commendable ambition, but here Ayer is less assured; rather than complexity, we have a lack of finesse, as he unnecessarily rubs our noses in the dehumanisation of characters, none of whom feels fully drawn. This failure is most evident in the sergeant. Pitt is unable to mesh Collier's intelligence and sensitivity with the cruel streak that forces Norman to shoot a German prisoner in the back, and who allows his crew to terrorise a pair of German women in a captured town.

Norman's sudden transformation from innocent to killing machine, along with the film's exciting but preposterous finale, suggest more common failings, of too much machismo and adrenalin. Both Spielberg's Saving Private Ryan and the TV series Band Of Brothers achieved physical and psychological realism without giving in to the rush.