This is most definitely not the Walt Whitman you encountered in high school, or the "Good Gray Poet" you thought you understood in college. In fact, forget virtually everything you thought you knew about Whitman, because Robert Roper has some serious surprises in store for you.

The amazingly productive Roper -- whose work has appeared in everything from the New York Times to National Geographic, and whose previous book, "The Fatal Mountaineer," the biography of American climber/philosopher Willi Unsoeld, was an international bestseller -- has turned the white light of critical analysis on the great poet. The result is a portrait more fully human, more emphatically flesh and blood, and exponentially more interesting than the Currier & Ives manqué we had come to know.

The author's focus is the Civil War, which was the defining moment for the Whitman family as well as the nation. Whitman, who was born in 1819, was too old to serve in the Union army when war erupted in 1861, although his heart was in the ranks. His brothers George and Andrew enlisted in Brooklyn regiments (brother Jeff was drafted, but he paid a man $400 to take his place, a common practice). Andrew died of disease in 1863; George not only survived the war, but distinguished himself in some of the most ferocious battles.

It was George's wound at Fredericksburg, Va., in December 1862 that brought Walt to the front -- and a rendezvous with the war as few writers of his era experienced. Rather than return to New York (George's wound was fairly superficial), Walt went to Washington and landed a job, working in a patent office by day and tending wounded soldiers at night. It was in the wards that he came to fully understand the war's true cost, the terrible price that was exacted on flesh and bone -- and the human psyche.

Roper does a superb job distilling Whitman's disparate experiences and weaving them into a seamless narrative, explaining, for example, how the ribbons of information he gathered were woven ultimately into "Drum-Taps" (1865) and layered into his subsequent works. Whereas "Leaves of Grass" (1855) was essentially self-absorbed and insular, Whitman's later verse took on a more expansive, passionate and altruistic hue.

His personal life reflected this change. Roper's handling of the homoerotic aspect of Whitman persona is candid, provocative and refreshingly unclouded by sophistry.

It's hard to imagine now, but Whitman was pretty well washed up as a poet by the time the war broke out. His "Leaves" had faded in popularity despite the encomiums heaped upon him by the thin-lipped New England aesthetes Emerson and Thoreau. If that weren't enough, his family was dysfunctional cubed. The war, for all its horrors, saved him.

Whitman famously remarked once that "the real war will never get in the history books." It has, and now, so, too, has the real Whitman.

Michael J. Bonafield is a copy editor for the Star Tribune.