But unfortunately, this muddled epic that attempts to set what is essentially a western in 19th-century New York City, and to combine it with a tendentious, even dishonest history lesson, is in other ways a disappointment.

The film is marred by sketchy characters, a predictable storyline, stilted dialogue, empty symbolism and a theatricality that's enjoyable but serves no thematic purpose.

Plot elements that recall Homeric epic (the gangs cite "the ancient laws of combat"), Shakespeare (its hero is an inarticulate Hamlet) and Christian mythology clash awkwardly with the Dickensian setting and confused historical agenda of "Gangs."

Though never dull and often visually beautiful, this work of operatic sweep doesn't fulfill its own ambitions.

It begins on a snowy morning in 1847 in Five Points, a lawless corner of New York. There, an Irish-Catholic immigrant street gang called the Dead Rabbits, led by "Priest" Vallon (Liam Neeson), emerges from basement caves to fight a coalition of native gangs led by Cutting. In the midst of the ferocious battle, Vallon is slain by Cutting as Vallon's 5-year-old son watches.

Sixteen years later, the boy, Amsterdam (Leonardo DiCaprio), returns from an orphanage planning to avenge his father. Hiding his real identity, Amsterdam joins Cutting's gang - now the undisputed master of Five Points - and soon finds himself a favorite of its leader.

Cutting is ruthless but he's also charming, lyrically articulate and faithful to his obsolete code of honor. As he increasingly treats Amsterdam like a son, the boy becomes conflicted in his loyalties.

Amsterdam gets further confused by his attraction to Jenny (Cameron Diaz), a pickpocket who is close to Cutting, and by the urgings of his father's old comrade McGinn (Brendan Gleeson) that he rebuild the Dead Rabbits and fight Cutting for control of Five Points.

Meanwhile, President Lincoln has ordered a draft, which provokes enormous anger - unlike the Uptown rich, the poor cannot buy themselves exemptions - that explodes into the violence of the 1863 Draft Riots just as Amsterdam and Cutting ultimately face off. DiCaprio, excellent in the forthcoming "Catch Me If You Can," is adequate in an underwritten role - paling in contrast to Day-Lewis, who's given every good line.

Diaz, an underrated dramatic actress, is nevertheless implausible here.

But the most infuriating thing about "Gangs" is the way it's so scrupulous in its recreation of period clothing and decor, and yet so grotesquely inaccurate in other respects.

The problem isn't invented details like a naval bombardment, or the way Scorsese and co. are so oblivious of slavery's signifigance as to suggest the Civil War and the battle for Five Points were both merely a struggle for ethnic turf.

Instead, it's the way the film turns Cutting's nativists into the most virulent racists and Amsterdam's Irish-Catholic immigrants into brotherhood-of-man types.

The narration flat-out lies that it was a generic multi-ethnic mob that took to the streets in July 1863: In real life, it was the Irish who descended on the city's black quarters - setting afire homes and churches and killing and torturing all the African-Americans they could find.

At the time, blacks were the city's skilled artisans and working class. The savage, anti-black frenzy of the Irish immigrants - fueled by their resentment of black social and economic superiority as well as their own hostility to the draft and the abolitionist cause - is whitewashed by the film.

Though a voiceover notes the violence against blacks, the effect as a whole is an egregious revision of history to rank with "Birth of a Nation" - and unworthy of America's most lauded filmmaker.