The men in this photograph are believed to be O'Sullivan (right) and Gardner (left). See Timothy O'Sullivan, American's Forgotten Photographer, by James D. Horan, copyright 1966, pp. X,125. Timothy H. O'Sullivan (1840-14 Jan. 1882) Photographer whose career began as an apprentice operator in Mathew Brady's daguerreotype studio in New York City. Based out of Washington D.C., O'Sullivan photographed military sites and personnel during the Civil War. Followed General William Tecumseh Sherman through South Carolina from December 1861 to May 1862. Over the next three years, O'Sullivan worked for Alexander Gardner photographing soldiers, war equipment, and the aftermath of many significant battles. Following the Civil War, O'Sullivan participated in a number of important scientific and military surveys of the western United States. Alexander Gardner (October 17, 1821 � December 10, 1882) A Scottish photographer who emigrated to the United States in 1856. Based out of Washington D.C., Gardner was appointed chief photographer under the jurisdiction of the�U.S. Topographical Engineers and later became a staff photographer under General�George B. McClellan. Between 1862 and 1865, Gardner followed General Ambrose Burnside and General Joseph Hooker and photographed the Battle of Fredericksburg, Battle of Gettysburg, and the Siege of Petersburg. Gardner is also well known for photographing President Abraham Lincoln. After the Civil War, he photographed Native Americans visiting Washington, D.C. and gave up photography to start an insurance company.