Primary Documents

Primary Documents: U.S. Ultimatum to Germany Regarding Unrestricted U-Boat Warfare, 18 April 1916
This is an abstract of The Document below. It is copied DIRECTLY from the Website cited below to elaborate on the initial document. IT IS CITED BELOW.

Reproduced below is the text of U.S. President Woodrow Wilson's ultimatum to the German government regarding the latter's use of U-boats.

In his ultimatum, dated 18 April 1916, Wilson condemned Germany's policy of unrestricted submarine warfare, which resulted in merchant vessels being sunk without warning should they be suspected of trading with the Allies.

Wilson warned that the U.S. would not tolerate the continuation of such a policy and demanded it be revoked by the German government (a stance re-iterated in a speech to Congress the following day).

Wilson had been spurred into action by the sinking of the British passenger ship Sussex while it was in the English Channel. Several U.S. citizens were among those drowned. Germany initially denied sinking the Sussex but subsequently admitted doing so.

Alarmed by the U.S. stance the German government - in the form of Foreign Minister Gottlieb von Jagow - withdrew its policy, noting that in future a clear warning would be given before ships were torpedoed. The Naval Minister, Alfred von Tirpitz, was furious, and later attributed Germany's wartime defeat to its weakness at this time in the face of U.S. opposition.

Germany's reintroduction of the policy in February 1917 led to the U.S. breaking off diplomatic relations with Germany.
Source Records of the Great War, Vol. IV, ed. Charles F. Horne// http://www.firstworldwar.com/source/uboat1916_usultimatum.htm