"RIDE WITH the Devil," adapted from Daniel Woodrell's novel "Woe to Live On," turns on a fascinating idea: While the bigger battles of the Civil War are raging elsewhere, a couple of friends join the pro-South Bushwhackers, whose purpose is to launch guerrilla attacks on the Yankees in the desolate backwoods.

Among the volunteers: Jake Roedel (Tobey Maguire), the son of a German immigrant who lives in Missouri, and Jack Bull Chiles (Skeet Ulrich), whose father owns a plantation, also in Missouri.

Their Bushwhacker unit, headed by one "Black John" (James Caviezel), includes the emotionally unstable Pitt Mackeson (Jonathan Rhys-Meyers), the more affable George Clyde (Simon Baker-Denny) and Daniel Holt (Jeffrey Wright), a former slave of George's who has joined the southern cause.

As the season gets colder, Jake and Jack hole up in an underground dugout shelter, depending on the charity of Sue Lee (Jewel), a widow living in the vicinity.

It's the beginning of a long, unmerciful struggle, as the renegades try to avoid getting picked off by the federalists. On a moral level, Jack and Jake also find themselves having to defend their growing friendship with Daniel to the more radical Bushwhackers. Even Sue Lee has problems accepting Daniel.

"Ride With the Devil," scripted by James Schamus and directed by Ang ("Sense and Sensibility") Lee, has some great moments -- particularly during its close-in, well-staged battles.

But it only scratches at its own potential. We get a respectable potboiler with a little bit of everything: two personable rebels (Maguire and Ulrich), one raving psycho (Rhys-Meyers), one freed slave (Wright) and one southern widow (Jewel). And this being the Civil War, we get a gruesome amputation by hacksaw.

But there isn't a sense of America being torn apart at the seams, or even a desire to see what happens next in the story. Like those holed-up rebels, we're forced to wait and watch, hoping our creeping, armchair numbness gets relief courtesy of those nasty, cruel skirmishes. Yes, civil war is terrible and heartbreaking. But it's even worse when it's not entertaining.

RIDE WITH THE DEVIL (R, 138 minutes) -- Contains hacksaw surgery, racial epithets and brief nudity. Area theaters.