Operation Hannibal was a German military operation involving the withdrawal of German troops and civilians from East Prussia in mid-January 1945 as the invading Soviet Red Army advanced during the East Pomeranian Offensive.
By early January 1945, Karl Dönitz had realized that Germany was soon to be defeated and, wishing to save his submariners, had radioed a coded message on January 23 to Gdynia (Gotenhafen) to flee to the west and the operation codename "Hannibal." Doenitz's avowed aim had been to evacuate as many people as possible away from the Soviets.
However, as late as April 1945, Adolf Hitler believed the war had to go on. The flood of refugees eventually turned the operation into one of the largest emergency evacuations by sea in history (over a period of four months some 1100 German ships (including ore haulers, freighters, naval vessels and fishing boats) would transport over two million people across the Baltic Sea to Germany

Operation
In early March, a task force comprised of the pocket battleship Admiral Scheer accompanied by three destroyers and the T-36 torpedo boat were giving cover to a German bridgehead near Wollin. During that operation, naval landing crafts managed to evacuate over 75,000 refugees who had been isolated in that area. They were taken to larger warships and other transports laying offshore. While a number of big transports were sunk, large liners such as the Deutschland managed to break through and carry up to 11,000 men each. During the night of April 4-5, a flotilla of small boats and landing crafts evacuated over 30,000 refugees from the Oxhofter Kampe and took them to Hela. It is estimated that nearly 265,000 people were evacuated from Gdańsk (German: Danzig) to Hela during the month of April alone. On April 15, another large convoy consisting of four liners and other transports left Hela with over 20,000 refugees. From May 1 to May 8, over 150,000 survivors were evacuated from the beaches of Hela. On the last day of the war, a convoy consisting of 65 small vessels left the Latvian city of Liepāja (Libau) with 15,000 men. Three hundred of them who had boarded the last of the small ships were captured by Soviet warships.