Unrestricted Submarine Warfare During World War I

On this day in 1917, Germany announces the renewal of unrestricted submarine warfare in the Atlantic as German torpedo-armed submarines prepare to attack any and all ships, including civilian passenger carriers, said to be sighted in war-zone waters.

When World War I erupted in 1914, President Woodrow Wilson pledged neutrality for the United States, a position that the vast majority of Americans favored. Britain, however, was one of America’s closest trading partners and tension soon arose between the United States and Germany over the latter’s attempted blockade the British Islands. Several U.S. ships traveling to Britain were damaged or sunk by German mines and, in February 1915, Germany announced unrestricted warfare against all ships,

The typical U-boat was 214 feet long, carried 35 men and 12 torpedoes, and could travel underwater for two hours at a time. In the first few years of World War I, the U-boats took a terrible toll on Allied shipping.

In early May 1915, several New York newspapers published a warning by the German embassy in Washington that Americans traveling on British or Allied ships in war zones did so at their own risk. The announcement was placed on the same page as an advertisement for the imminent sailing of the British-owned Lusitania ocean liner from New York to Liverpool. On May 7, the Lusitania was torpedoed without warning just off the coast of Ireland. Of the 1,959 passengers, 1,198 were killed, including 128 Americans.

The German government maintained that the Lusitania was carrying munitions, but the U.S. demanded reparations and an end to German attacks on unarmed passenger and merchant ships. In August 1915, Germany pledged to see to the safety of passengers before sinking unarmed vessels, but in November sank an Italian liner without warning, killing 272 people, including 27 Americans. Public opinion in the United States began to turn irrevocably against

Two days later, British authorities gave the U.S. ambassador to Britain a copy of what has become known as the Zimmermann Note coded message from German Foreign Secretary Arthur Zimmermann to Count Johann von Bernstorff, the German ambassador to Mexico. In the telegram, intercepted and deciphered by British intelligence, Zimmermann stated that, in the event of war with the United States, Mexico should be asked to enter the conflict as a German ally. In return, Germany would promise to restore to Mexico the lost territories of Texas, New Mexico and Arizona. On March 1, the U.S. State Department published the note and America was galvanized against Germany once and for