The outbreak of World War I ended the Trieste service, and Carpathia remained on the Liverpool-New York route from 1915 until 17 July 1918, when she was torpedoed and sunk by U55, 170 miles west of Bishop Rock. Five crew were killed, but the remaining 215 on board, including 57 passengers, were rescued by HMS Snowdrop.

Carpathia's greatest fame, of course, is unrelated to her service to Cunard. On the dark, moonless night of 14-15 April 1912, Carpathia raced 58 miles through a North Atlantic icefield in response to the distress calls of White Star's R.M.S. Titanic. Although she arrived on scene after Titanic foundered, she rescued all 705 survivors in Titanic's lifeboats and returned them to New York.