Marshal Joseph Joffre in the US 1917, Harris & Ewing Collection. Image courtesy Library of Congress.
- The US Senate enthusiastically receives French Marshal Joseph Joffre and former French Prime Minister Rene Viviani. The Viviani-Joffre Mission to the United States in April-May 1917 aims to determine the scope of cooperation between American and Allied forces following America’s entry into the war on 6 April.
- A German aircraft torpedoes and sink the British collier SS Gena in the North Sea off Southwold
- British Navy submarine E-54 Sinks the German submarine U-81 in the Atlantic Ocean west of Ireland; 31 of U-81’s crew die, seven survive
