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.

Dorchester is best remembered today for the actions of four of the Army officers among the military personnel being transported overseas for duty: the Four Chaplains who died because they gave up their life jackets to save others. These chaplains included Methodist minister George L. Fox, Reformed Church in America minister Clark V. Poling, Catholic Church priest John P. Washington and Rabbi Alexander B. Goode.

Congress established February 3 as "Four Chaplains Day" to commemorate this act of heroism, and on July 14, 1960, created the Chaplain's Medal for Heroism, presented posthumously to the next of kin of each of the chaplains by Secretary of the Army Wilber M. Brucker at Fort Myer, Virginia on January 18, 1961.

On January 23, 1943, Dorchester left New York harbor, bound for the Army Command Base at Narsarsuaq in southern Greenland. SG-19 consisted of six ships: SS Dorchester, two merchant ships (SS Lutz and SS Biscaya) that were leased by the United States from the Norwegian government-in-exile, and their escorts, the small United States Coast Guard cutters Comanche, Escanaba (both 165 feet), and Tampa (240 feet).

During the early morning hours of February 3, 1943, at 12:55, Dorchester was torpedoed by German submarine U-223. The damage was severe, boiler power was lost, and there was inadequate steam to sound the full 6-whistle signal to abandon ship, and Dorchester sank by the bow in about 20 minutes.

Loss of power prevented the crew from sending a radio distress signal, and no rockets or flares were launched to alert the escorts. A severe list prevented launch of some port side lifeboats, and some lifeboats capsized through overcrowding.

Survivors in the water were so stiff from cold they could not even grasp the cargo nets on rescue vessels.

The crew of Escanaba employed a new "retriever" rescue technique whereby swimmers clad in wet suits swam to victims in the water and secured a line to them so they could be hauled onto the ship.

By this method, Escanaba saved 133 men (one died later) and Comanche saved 97 men of the 904 aboard Dorchester.

The sinking of Dorchester was the worst single loss of American personnel of any American convoy during World War II.

Life jackets offered little protection from hypothermia, which killed most men in the water. Water temperature was 34 °F (1 °C) and air temperature was 36 °F (2 °C). When additional rescue ships arrived on February 4 "hundreds of dead bodies were seen floating on the water, kept up by their life jackets."

https://en.wikipedia.org/wiki/SS_Dorchester#