Dorchester was a coastal passenger steamship requisitioned and operated by the War Shipping Administration (WSA) in January 1942 for wartime use as a troop ship allocated to United States Army requirements. The ship was operated for WSA by its agent Atlantic, Gulf & West Indies Steamship Lines (Agwilines). The ship was in convoy SG 19 from New York to Greenland transiting the Labrador Sea when it was torpedoed by a German U-boat on February 3, 1943. The ship sank with loss of 674 of the 904 on board with one of the 230 survivors lost after rescue. The story of four Army chaplains, known as the "Four Chaplains" or the "Immortal Chaplains," who all gave away their life jackets to save others before they died, gained fame and led to many memorials.

The Four Chaplains, also referred to as the Immortal Chaplains or the Dorchester Chaplains, were four chaplains who died rescuing civilian and military personnel as the American troop ship SS Dorchester sank on February 3, 1943, in what has been referred to as the second-worst sea disaster of World War II.