Sussex Pledge: Definition & History

Instructor: Jason McCollom

Jason has a PhD.

In the early years of World War I, German submarines were sinking any ship in sight. Pressured by the U.S., the Germans issued the Sussex Pledge and promised to only target military ships. Learn about the pledge and test your knowledge with a quiz.

Unrestricted Submarine Warfare

Imagine standing on the deck of a cruise ship, looking out on endless open miles of frigid North Atlantic waters. There's a war going on thousands of miles away, but you're not worried because the ship you're on is a passenger liner. Or is it? All of a sudden, you hear an explosion and the ship tilts, spilling hundreds of holiday-goers into the icy sea.

As it turns out, your holiday cruiser was actually carrying munitions. This was the situation during World War I when German submarines sank the French civilian ferry the Sussex in 1916. Though the U.S. was not yet part of the war, two Americans died in this torpedo attack, and President Woodrow Wilson demanded Germany cease targeting civilian ships in the North Atlantic. Not wanting to provoke the Americans to join the war against them, the Germans issued the Sussex Pledge and promised to only attack military crafts. But would the pledge hold?

First, lets look at some background information.

During World War I (1914-1918), German submarines, called U-boats (in German, Unterseeboot), engaged in unrestricted submarine warfare. This meant they would torpedo any vessel associated with Germany's enemies, Britain and France. But this also meant that American ships in the North Atlantic were targeted because America continued to trade with Germany's enemies.

The Lusitania and the Arabic

On May 7, 1915, German U-boats sunk the British passenger liner Lusitania. Though a civilian vessel, the Lusitania was carrying war materiel. More than 1,000 passengers died, including 128 Americans. U.S. President Woodrow Wilson's Lusitania note demanded an end to unrestricted submarine warfare, and the Germans complied.

Despite this, later in 1915, German subs sunk the British ship Arabic as it sailed towards New York. In response to the death of two Americans on board the Arabic, the Germans issued the Arabic Pledge in September 1915, which reiterated Germany's commitment to avoid indiscriminate attacks on non-military vessels in the North Atlantic.

The Sussex Pledge

In March 1916, German U-boat captains spotted the French vessel Sussex. It was a civilian liner--a ferry--but the Germans believed the Sussex was a military craft laying mines to destroy German ships. On March 24, the U-boats fired torpedoes at the Sussex, and though it didn't sink, it arrived at port heavily damaged. Ultimately 80 people died, including two American citizens.

Cross-channel ferry Sussex at Boulogne after being torpedoed in March 1916. The entire forepart of the ship was destroyed in the attack.

President Wilson was furious at this breaking of the Arabic Pledge. On April 19, Wilson demanded the Germans cease immediately in targeting civilian passenger vessels. If they refused, he warned, the U.S. would break off diplomatic relations with Germany. This was a powerful indictment of the use of unrestricted sub warfare and a veiled threat that the U.S. might join the Allies to fight against Germany. The Germans had their hands full fighting the British and French in Europe and didn't want the the Americans to join the war.

President Woodrow Wilson presented Germany with the ultimatum that led to the Sussex Pledge

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