Operation Hannibal was a military operation that started on 21 January 1945, on the orders of Admiral Karl Dönitz, withdrawing German troops and civilians from Courland, East Prussia, and the Polish Corridor.
The flood of refugees turned the operation into one of the largest emergency evacuations by sea in history — over a period of 15 weeks, somewhere between 494 and 1,080 merchant vessels of all types and numerous naval craft, including Germany's largest remaining naval units, transported about 800,000 – 900,000 refugees and 350,000 soldiers across the Baltic Sea to Germany and occupied Denmark.
This evacuation was one of the Kriegsmarine's most significant activities during the war.

The greatest recorded loss of life from a ship sinking occurred during this operation, when the transport ship Wilhelm Gustloff was hit by three torpedoes from the Soviet submarine S-13 in the Baltic Sea on the night of 30 January 1945.
She sank in under 45 minutes; figures for the number of deaths vary from 5,348, to 7,000 or 9,400.
The 949 survivors were rescued by Kriegsmarine vessels led by the cruiser Admiral Hipper, although it is claimed that "the big warship could not risk heaving to, with a submarine close by".
Also, on 10 February, the SS General von Steuben left Pillau with 2,680 refugees on board; it was hit by torpedoes just after departure, killing almost all aboard.
Operation Hannibal was a military operation that started on 21 January 1945, on the orders of Admiral Karl Dönitz, withdrawing German troops and civilians from Courland, East Prussia, and the Polish Corridor. The flood of refugees turned the operation into one of the largest emergency evacuations by sea in history — over a period of 15 weeks, somewhere between 494 and 1,080 merchant vessels of all types and numerous naval craft, including Germany's largest remaining naval units, transported about 800,000 – 900,000 refugees and 350,000 soldiers across the Baltic Sea to Germany and occupied Denmark. This evacuation was one of the Kriegsmarine's most significant activities during the war.
The greatest recorded loss of life from a ship sinking occurred during this operation, when the transport ship Wilhelm Gustloff was hit by three torpedoes from the Soviet submarine S-13 in the Baltic Sea on the night of 30 January 1945. She sank in under 45 minutes; figures for the number of deaths vary from 5,348, to 7,000 or 9,400. The 949 survivors were rescued by Kriegsmarine vessels led by the cruiser Admiral Hipper, although it is claimed that "the big warship could not risk heaving to, with a submarine close by". Also, on 10 February, the SS General von Steuben left Pillau with 2,680 refugees on board; it was hit by torpedoes just after departure, killing almost all aboard.
Evacuation of East Prussia