The Cunard liner Lusitania was eleven miles off the Old Head of Kinsale, near the end of a crossing from New York, when a single torpedo from a German submarine struck her starboard side. A second, larger explosion followed from inside the ship, whose cause is still argued over, and she listed so sharply that most of the lifeboats could not be launched. She sank in eighteen minutes. Of 1,962 people aboard, 1,198 died, among them 128 Americans and almost a hundred children.

Germany argued that the ship carried munitions, which she did, and that a warning had been published in New York newspapers, which it had. Britain used the sinking as propaganda and suppressed inconvenient findings at the inquiry. The deaths of the American passengers shifted opinion in the United States and are part of the road to its entry into the war two years later. The bodies recovered were brought to Queenstown, now Cobh, and many were buried in three mass graves in the Old Church Cemetery above the town, where the memorial stands.