The ship was named after Wilhelm Gustloff, the assassinated German leader of the Swiss Nazi party. It was requisitioned into the Kriegsmarine (German Navy) on 1 September 1939. The MV Wilhelm Gustloff served as a hospital ship in 1939 and 1940. Beginning on 20 November 1940, it was stripped of medical equipment and repainted from its hospital ship colors (white with a green stripe) to standard naval grey. The Wilhelm Gustloff was then assigned as a floating barracks for naval personnel in the port of Gdynia which was located in Nazi occupied Poland (renamed during German occupation to Gotenhafen), near Gdańsk, Poland.
The Wilhelm Gustloff′s final voyage was during Operation Hannibal in January 1945, when it was sunk while participating in the evacuation of civilians, military personnel, and Nazi officials who were surrounded by the Red Army in East Prussia. The Gustloff was hit by three torpedoes from the S-13 in the Baltic Sea under the command of Alexander Marinesko on the night of 30 January 1945 and sank in less than 45 minutes. An estimated 9,400 people were killed in the sinking, possibly the largest known loss of life occurring during a single ship sinking in recorded maritime history.