World War I: German naval officer Wilhelm Werner murdered 19 captured crew members of the British cargo ship Torrington by submerging U-55 when they were on deck.

World War I or the First World War, also known as the Great War, was a global conflict between two coalitions: the Allies and the Central Powers. Main areas of conflict included Europe and the Middle East, as well as parts of Africa and the Asia-Pacific. There were important developments in weaponry including tanks, aircraft, artillery, machine guns, and chemical weapons. One of the deadliest conflicts in history, it resulted in an estimated 30 million military casualties, plus another 8 million civilian deaths from war-related causes and genocide. The movement of large numbers of people was a major factor in the deadly Spanish flu pandemic.

Wilhelm Werner was a German naval officer in the First World War and SS staff general in the Second World War. As commander of U-55 during World War I he participated in several controversial actions, including the murder by drowning of surrendered crews of some of the ships he sank and attacks on marked hospital ships. The British government sought to prosecute Werner at the Leipzig war crimes trials, but he fled to Brazil, where he was reported to have worked as an architect and a coffee planter.

SS Torrington was a British cargo steamship that was built in England in 1905, owned and registered in Wales, and sunk by a German U-boat in 1917. She was a turret deck ship: an unusual hull design that was developed by William Doxford & Sons of Sunderland in the 1890s.

SM U-55 was one of the six Type U-51 U-boats of the Imperial German Navy during the First World War.