Everyone thinks they know George Armstrong Custer, whether from school reports or TV and movies or crossword puzzles. He was that general with the curly hair who got clobbered by the Indians somewhere out West, was it Wyoming? Montana? Had it coming. Something of a nut job, wasn't he?

We may think we know Custer. However, as author T.J. Stiles shows in riveting detail in his commanding new biography, "Custer's Trials: A Life on the Frontier of a New America," few of us really understand him, overshadowed as he's been all these years by his controversial demise.

This is Stiles' first book since "The First Tycoon," a groundbreaking biography of robber baron Cornelius Vanderbilt that won the Pulitzer Prize and the National Book Award. Vanderbilt was in dire need of a modern biography; Custer, who is something of a cottage industry for writers, not so much.

But Stiles, who grew up in Foley, Minn., and was educated at Carleton College in Northfield, has given us a different way to look at the flesh-and-blood man and his times, before his Last Stand made it nearly impossible to see him with clear eyes.

This is that rare, practically unthinkable Custer book that devotes only about 15 of its 582 pages to the Battle of the Little Bighorn, the 1876 High Plains clash that cemented Custer's fame (or infamy) when he led his regiment to their deaths at the hands of a superior force of Lakota and Cheyenne chiefs and warriors.

Instead, Stiles focuses on Custer's huge ambition as the son of an obscure Ohio blacksmith, someone who yearned to be known for more than just military feats. Alas, he was confronted with an era in which the United States was rapidly changing — from the romantic small-town culture that had already made him a popular hero, and into an industrial urban-based society that he found alluring but harder to navigate.

Stiles renders the Boy General as a cross-grained narcissist of the highest order. At once supremely poised and deeply insecure, he was a Union officer who felt more at home in the South, a racist Democrat who espoused Republicanism to save his career, a devoted husband whose flirtations with women bedeviled his wife, a New York theater enthusiast who saw the battlefield as a stage for his own greatest scenes.

Custer was almost always just one step ahead of trouble of his own making, whether as a West Point cadet who barely graduated or an inveterate gambler who could have gotten tossed from the Army for stealing a prized thoroughbred stallion. Custer was a great fighter but a poor manager, and his massacre on the Montana plains doesn't come as a great surprise in the end, although he wasn't entirely to blame for that debacle.

But Stiles also shows how Custer, by the end of his short life — he was only 36 when he went to the Little Bighorn — was racing against time to escape the ultimate irony: becoming irrelevant in the modern, surging post-Civil War America that his war exploits had helped create.

Custer invested over his head in a Colorado silver mine with dubious prospects and lost the backing of Wall Street financiers. He hoped to make a mark as an intellectual in his writings about the West and the American Indian ("a savage in every sense of the word" and yet also "the fearless hunter, matchless horseman"), but never earned enough to consider it a livelihood.

Revered by the public, favored by some leaders and suspected by others (including President Grant), Custer had little choice but to return to the single thing for which he had always shown unquestioned talent and often brilliance — leading men into battle.

Luck was always a big part of his legend. But in the end that, too, would fail him. Stiles shows us not just how he got there, but why.

Kevin Duchschere is a Star Tribune reporter.