The Laconia incident was a series of events surrounding the sinking of a British passenger ship in the Atlantic Ocean on 12 September 1942, during World War II, and a subsequent aerial attack on German and Italian submarines involved in rescue attempts. RMS Laconia, carrying 2,732 crew, passengers, soldiers, and prisoners of war, was torpedoed and sunk by U-156, a German U-boat, off the West African coast. Operating partly under the dictates of the old prize rules, the U-boat's commander, Korvettenkapitän Werner Hartenstein, immediately commenced rescue operations. U-156 broadcast her position on open radio channels to all Allied powers nearby, and was joined by the crews of several other U-boats in the vicinity.

RMS Laconia was a Cunard ocean liner, built by Swan, Hunter & Wigham Richardson as a successor of the 1911–1917 Laconia. The new ship was launched on 9 April 1921, and made her maiden voyage on 25 May 1922 from Southampton to New York City. At the outbreak of the Second World War she was converted into an armed merchant cruiser, and later a troopship. She was sunk in the South Atlantic Ocean on 12 September 1942 by torpedoes. Like her predecessor, sunk during the First World War, this Laconia was also destroyed by a German submarine. Some estimates of the death toll have suggested that over 1,658 people were killed when the Laconia sank. The U-boat commander Werner Hartenstein then staged a dramatic effort to rescue the passengers and the crew of Laconia, which involved additional German U-boats and became known as the Laconia incident.