SM U-56[Note 1] was one of the 329 submarines serving in the Imperial German Navy in World War I. U-56 was engaged in the naval warfare and took part in the First Battle of the Atlantic.

On 2 November 1916, U-56 was attacked by gunfire from the Imperial Russian Navy destroyer Grozovoi off Khorne Island, Norway (near Vardø).

U-56 survived this attack.

U-56 dropped off the crew of the Norwegian merchant ship Ivanhoe ashore at 07:45 on 3 November 1916 at Lodsvik.

The Norwegian sailors were aboard the ship during the action of the previous day and their description matches with the Russian account.