USS Mercy (ID-1305/AH-4) was a hospital ship in the United States Navy during World War I. She was the first U.S. Navy ship of that name. The ship was previously known as SS Saratoga, a steamer for the Ward Line on the New York to Havana route, and considered the fastest steamship in coastal trade. Before being purchased by the Navy, the ship was briefly employed as United States Army transport ship USAT Saratoga, a career that ended after a collision off Staten Island, New York.