Jerome Loving, "Whitman, Walt," American National Biography Online, February 2000, http://www.anb.org/articles/16/16-01761.html.
The first two years of the war are fairly blank in the Whitman biography, but he surfaces again in the fall of 1862. His younger brother, George Washington Whitman, an officer in the Fifty-first Regiment of New York Volunteers, was reported in the New York papers to have been seriously wounded in the battle of Fredericksburg in December 1862. Whitman was dispatched to Washington, D.C., by anxious family members in Brooklyn to search for his brother in the more than forty wartime hospitals. Failing to find George there, he went to the battle site to find his brother only slightly wounded. He remained in camp with his brother's regiment for more than a week and then returned to the nation's capital, escorting a group of seriously wounded and dying soldiers. Once at his destination, he felt he could not return to civilian life in New York. He remained in Washington throughout the war and beyond, worked at various government jobs, and devoted himself to cheering up sick and wounded soldiers in the hospitals. This unselfish service earned him the titles of "wound dresser" and "the Good Gray Poet," but no government pension (which Whitman later said he would have refused anyway).