During Walt Whitman's decade in Washington, DC, 1863-1873, he labored intensely, at times seeming to have three lives at once. He wrote the most distinguished journalism of his career; came into his own as a writer of letters; crafted memorable Civil War poetry, Drum-Taps and Sequel to Drum-Taps and later folded it into heavily revised and expanded versions of Leaves of Grass; and produced his searching but also flawed critique of American culture,...