Walt Whitman was already famous for Leaves of Grass when he journeyed to the nation's capital at the height of the Civil War to find his brother George, a Union officer wounded at the Battle of Fredericksburg. Whitman eventually served as a volunteer hospital missionary, making more than six hundred hospital visits and serving over eighty thousand sick and wounded soldiers in the next three years. With the 1865 publication of Drum-Taps, Whitman became...