Let's get this one big caveat out of the way straight off: Wolfgang Petersen's $200 million blockbuster, "Troy," is pretty much a travesty of its source, Homer's great epic poem, "The Iliad." Classical purists will want to throw stones at this movie.

Major characters of the saga who live safely through Homer's telling get killed off. Sequences of the narrative are rearranged, often clumsily and for reasons that serve no clear dramatic purpose. And, oh yes, the decade-long war is compressed into less than two weeks.

Also, apparently in the interest of homophobia, the character of Patroclus is now Achilles' cousin, not his best friend, and the love the warrior feels for him - which motivates Homer's climax - is given to Briseis, elevated from minor slave girl to feisty Trojan princess.

One could go on like this all day. But the amazing thing about all this apparent disrespect is that it doesn't really matter. "Troy" is such an exhilarating piece of epic filmmaking that it pulls you in, sweeps you up and works very much as its own thing.

And at the end of its fast-moving, two-hour, 45-minute running time, it's taken us to roughly the same place as Homer, in its own way capturing all the pageantry, political complexity and rich characterization of Western literature's first great masterpiece.

Set 3,200 years ago, the story deals with the Greek war against the Asia Minor city of Troy that's sparked when Troy's prince, Paris (Orlando Bloom), makes off with Helen (Diane Kruger), the wife of Menelaus (Brendan Gleeson), brother of Agamemnon (Brian Cox), the head Greek king.

The Greeks draft their great but reluctant champion, Achilles (Brad Pitt), raise a fleet of 1,000 ships and sail across the Aegean Sea to get Helen back, but Troy lies behind huge walls that have never been breached and things quickly get bogged down.

In Homer's version, the quagmire that ensues is seen from three perspectives: the Greeks, the Trojans and the gods, who take sides in the conflict and keep coming down from Mount Olympus to directly enter the fray as allies of the mortals.

Like Robert Wise's 1955 "Helen of Troy" (a much inferior movie), Petersen's version leaves out the gods completely and tries to envision what this event might have been like if it had actually transpired and was later mythologized by Homer.

Having accepted that premise, he then faced the choice that has confronted all the directors of the computer-generated historical epics of recent years: to go for the gritty realism of a "Master & Commander" or the romance of a "Gladiator." He chose the latter.In fact, with its emphasis on graceful battle, beautiful bodies and not one but three romances, the film may have been inspired by the "Sword and Scandal" epics that filled the movie theaters of Petersen's youth. Steve Reeves would not be out of place here.And yet, as we might expect from the director of "Das Boot," the film rises above its romantic underpinning to be a riveting portrait of men in war. In a most satisfying way, it explores a spectrum of psychology and juggles an array of character strengths and flaws.It also works as spectacle. From its eye-boggling naval armada to its "Saving Private Ryan" of a beachhead to its vast panoramas of clashing armies, the film rivals the "Ring" trilogy as a showcase for the computer's ability to create massive, convincing battle scenes.Yet, also like the "Ring," "Troy" works mostly off its casting. Each of its major roles seems perfectly filled, with such gems as Brian Cox's magnificently malevolent Agamemnon, Brendan Gleeson's slovenly brutish Menelaus and Peter O'Toole's weak but noble King Priam of Troy.In the thankless role of Paris, Orlando Bloom strikes just the right chord of self-centered softness, but he also gives the cowardly character an appealing vulnerability and self-disapproval that explains why his family and nation might stand behind him.As Paris' brother, the great Trojan hero Hector, Eric Bana ("The Hulk") is so unexpectedly strong and yet so sympathetically human that he all but steals the picture. It could be the most successful bit of offbeat casting since Al Pacino played Michael Corleone.As Achilles, the beefed-up Brad Pitt sometimes trips on his faux-classical English accent, but he also finds his character. He's suitably conflicted off the field, and his personal interactions are all marred by just the right touch of hubris.In battle, he's deadly poetry in motion, a Diaghilev of a killing machine -- so effortlessly charismatic that, even with the film's several annoying concessions to his stardom, it would be hard to imagine a more compelling embodiment of Greek mythology's headiest hero.