On 7 May 1915, the British ocean liner RMS Lusitania was torpedoed and sunk by a German U-boat off the coast of Ireland. The vessel was travelling from New York to Liverpool when it was struck by a single torpedo, causing a secondary explosion that led the ship to founder in just eighteen minutes. Of the nearly 2,000 passengers and crew on board, 1,198 individuals lost their lives, including 128 American citizens. The speed at which the liner sank caused widespread horror and profound grief across the British public and the international community.

The tragedy served as a pivotal moment in the First World War, fundamentally altering global perceptions of the conflict at sea. The German government had previously declared the waters around the British Isles a war zone, warning that neutral vessels risked being targeted. However, the loss of civilian life on such a scale provoked intense international outrage and significantly damaged Germany's diplomatic standing. The event became a powerful symbol of the brutality of unrestricted submarine warfare, which had been employed by the German navy to disrupt vital supply lines to Britain.

While the sinking of the Lusitania intensified the debate regarding the morality and legality of submarine tactics, it did not immediately result in the United States entering the war. Nevertheless, the incident remained a potent rallying point for those advocating for Allied intervention. The disaster underscored the vulnerability of merchant shipping and forced a re-evaluation of maritime safety and naval strategy during the remainder of the conflict.

• The ship was struck by a German U-boat torpedo off the Irish coast.
• The vessel sank rapidly, resulting in the deaths of 1,198 people.
• The incident included the loss of 128 American citizens.
• It became a defining symbol of the dangers of unrestricted submarine warfare.
• The tragedy significantly influenced international opinion against Germany.