The Arabic pledge was a promise made by the German Empire during World War I to limit unrestricted submarine warfare. On May 7, 1915, Imperial German Navy U-boat sank the off the coast of Ireland. The Germans attacked the Lusitania without warning and the ship went down within 18 minutes. 1198 people on board died. The passenger liner had departed from the port of New York City with many American citizens on board, 128 of whom were killed when the ship sank (including a member of the famous Vanderbilt family). The U.S. government condemned the German action and U.S. President Woodrow Wilson protested this violation of the United States' neutral rights and threatened to sever diplomatic relations with Germany.