Immediately after the assassination of President Lincoln, the Sixth was ordered to Washington, D.C. A detachment was sent in pursuit of Booth and his accomplices. Dr. Mudd was arrested at Surrattsville, and Booth chased from Maryland into Virginia. The Sixth now having its headquarters on 7th Street, sent out each morning a detachment for escort duty during the trial of the conspirators in the assassination. And the entire regiment commanded by Colonel Fleming, did guard duty on Pennsylvania Avenue between the capitol and Georgetown during the "Grand Review."