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.