The Sussex plege was a promise made in 1916 during World War I by Germany to the United States prior to the latter's entry into the war. Early in 1916, Germany had instituted a policy of unrestricted submarine warfare, allowing armed merchant ships - but not passenger ships - to be torpedoed without warning. Despite this avowed restriction, a French cross-channel passenger ferry, the Sussex, was torpedoed without warning on March 24, 1916; the ship was severely damaged and about 50 lives were lost. Although no U.S. citizens were killed in this attack, it prompted President Woodrow Wilson to declare that if Germany were to continue this practice, the United States would break diplomatic relations with Germany. Fearing the entry of the United States into World War I, Germany attempted to appease the United States by issuing, on May 14, 1916, the Sussex pledge, which promised a change in Germany’s naval warfare policy. According to U-S-History.com, the primary elements of this undertaking were: