ATLANTA, Georgia (CNN) -- At its peak, it was more than 60,000 strong, a many-legged beast tramping and burning its way through the South at the end of the Civil War."It consumes everything in its path. It is an immense organism, this army. ... And any one of the sixty thousand of us has no identity but as a cell in the body of this giant creature's function, which is to move forward and consume all before it," says one of E.L. Doctorow's characters in "The March" (Random House).For Doctorow, author of the prize-winning and best-selling novels "Ragtime" and "Billy Bathgate," Sherman's march, a seven-month campaign across Georgia and the Carolinas following the general's taking of Atlanta in September 1864, was a chance to investigate its impact on some of those 60,000, with history lurking in the background."It seemed to me very different than anything else in the Civil War," says Doctorow in an interview at an Atlanta hotel, noting that he first thought of writing what he calls his "road novel" 20 years ago."The idea of an army of 60,000 men on the march, living off the land, going through plantations, taking the livestock, horses, mules and every bit of food they could find, and destroying Confederate infrastructure -- the armories, machine shops, cotton mills, railroads ... just depriving the Confederacy of everything it needed to maintain itself. ... It seemed to me I could make a novel out of that and find something."It was "another kind of society," he adds. "I wrote the book to discover the secrets of that march. ... Everybody in the march was changed."O untimely deathIn that spirit, Doctorow's "no identity"-speaking character, Dr. Wrede Sartorius, isn't completely correct. In Doctorow's work, the march is made of many individuals, each of whom brings his or her specific personality to the journey.There is Dr. Sartorius himself, a methodical, inventive surgeon; Emily Thompson, the daughter of a Southern judge who becomes an assistant to Sartorius; Pearl, a freed slave; Arly and Will, two Confederate soldiers who change sides (and identities) as the opportunity provides; Calvin Harper, a photographer's black assistant; the brittle and inscrutable Sherman himself; and a variety of supporting characters, some real, some fictional, all part of the march's fabric, like the colors of a serpent.Sherman was particularly fascinating, Doctorow says. Early in the war, the Union general suffered a nervous breakdown and was criticized by newspapers as "crazy and useless," in Doctorow's words. (A famous photo, taken after he returned to the battlefield, shows him with arms crossed, his eyes the receptacles of a gloomy, thousand-yard glint.) His tactics during the march were alternately ruthless and thoughtful. Success prompted those same critics to hail him as a hero, while Southerners -- particularly Georgians -- retain a lasting enmity for the man. "He did have a lot of guilt," Doctorow says. "When the war was over, he went down South to oversee rescue and relief efforts." (Before the war, Sherman -- who was born in Ohio -- had headed what would become Louisiana State University.)Sherman survived the war. Not all Doctorow's characters do, and for some, death comes suddenly and capriciously.One soldier is caught in a Confederate ambush; another character has his head blown off by a cannonball. A third character, his memory destroyed by a spike in his head, exists for many pages and abruptly kills himself.Doctorow, the impassive narrator, dictates these demises with little comment or judgment -- or, sometimes, advance knowledge."You make discoveries," says the author. "The experience is just the same as the reader's. These characters came to me whole, with names, their behaviors, their diction, without any calculation or planning or outline. You write to find out what you're writing."'I don't have a style'Though Doctorow is a critic of the Iraq war and President Bush, he says he didn't write the book to illustrate the brutality of war. "When you're writing about the past you're inevitably writing about the present, but it wasn't a conscious, allegorical intention," he says. "I leave it for the reader to decide how relevant that is."The book's rootless refugees also evoke comparison to the victims of Hurricane Katrina -- an assessment one of Doctorow's friends made after the book came out.Doctorow's books, almost always about the past, have often stirred comparisons to the present. They've also grappled with a variety of themes, mixing styles, real-life figures and fictional characters -- including the snapshots of Sigmund Freud, Theodore Dreiser and Coalhouse Walker Jr. in 1975's "Ragtime," the sunny memoir-like telling of 1985's "World's Fair" or the Bronx working-class argot of 1989's gangster tale "Billy Bathgate.""I've always found it necessary to have the illusion that I don't have a style -- that each book demands its own style," he says. Most of the books use fictive narrators, he says, and "each of those narrators has his own place in the world -- his own language."Authors that are too aware of their style are in trouble," Doctorow says. "I know that Hemingway finally began to hear his own voice, and I think that was the beginning of the end for him.""The March" has earned wide praise and is selling well, currently standing at No. 11 on The New York Times' best-seller list. As much as Doctorow's writing, its success is testament to the hold the Civil War still has on the United States, and the ever-resonant issues raised by that conflict.But Doctorow cautions against reading it as a judgment on Sherman, the Confederacy, or even the Civil War."I think it's impossible to read this book and decide it's a clear, propagandistic effort to distinguish between good and evil," he says. "I don't think any successful novel can reside anywhere but ambiguity."