At the start of the American Civil War, Whitman moved from New York to Washington, D.C., where he held a series of government jobs—first with the Army Paymaster's Office and later with the Bureau of Indian Affairs. He volunteered in the army hospitals as a nurse. Whitman's poetry was informed by his wartime experience, maturing into reflections on death and youth, the brutality of war, and patriotism. Whitman's brother, Union Army soldier George Washington Whitman, was taken prisoner in Virginia in September 1864, and held for five months in Libby Prison, a Confederate prisoner-of-war camp near Richmond. On February 24, 1865, George was granted a furlough to return home because of his poor health, and Whitman travelled to his mother's home in New York to visit his brother. While visiting Brooklyn, Whitman contracted to have his collection of Civil War poems, Drum-Taps, published. In June 1865, James Harlan, the Secretary of the Interior, found a copy of Leaves of Grass and, considering the collection vulgar, fired Whitman from the Bureau of Indian Affairs.