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The assassination of Archduke Ferdinand (Library of Congress). This was the immediate cause of World War I. Gavrilo Princip, a Serbian nationalist involved with the terrorist group called the black hand, assassinated Archduke, and his wife. This led Austria- Hungary to declare war on Serbia. Germany declared war on Russia due to its alliance with Serbia. The war expanded due to the involvement of all mutual allies (McCormick). -
The sinking of the Lusitania (Library of Congress). A German U-boat sunk the British passenger ship the Lusitania. About 1,000 passengers were killed including around 128 Americans. Americans were frustrated because the people on board were not made aware before the sinking. After the sinking of the Lusitania, Germany promised to stop unrestricted submarine warfare (McCormick). -
The “Sussex Pledge” was accepted (Milestone). Less than one year after the sinking of the Lusitania, Germany torpedoed an unarmed French boat, the Sussex in the English Channel in March 1916. Wilson threatened to sever diplomatic relations with Germany unless the German government refrained from attacking passenger ships. In May 1916, the German government accepted the terms and conditions of the “Sussex Pledge” (Milestones). -
By January 1917, the German Navy convinced the military leadership that a resumption of unrestricted submarine warfare could defeat Great Britain soon. The German government decided to resume unrestricted submarine warfare despite the warnings of Wilson. Throughout February and March of 1917, German submarines targeted and sank multiple American ships. After trying to stay out of war, Wilson finally declared war on Germany (Milestones). -
Woodrow Wilson presents his Fourteen Points speech to Congress (Library of Congress). President Woodrow Wilson outlined his proposals for postwar peace. The second point outlined the absolute freedom of the seas which was a direct solution to prevent unrestricted submarine warfare. Wilson strived for free trade on the seas during war and peace. Wilson presents the Fourteen Points that are required for peace to Congress (National Archives). -
In 1918 both sides launched renewed offensives to win the war; however, the fighting efforts failed. In September, Allied offensives were able to successfully drive the exhausted German army back to German borders. After a deadly outbreak of influenza, the governments of both Germany and Austria- Hungary began to lose support. On November 11, 1918, Germany signed an Armistice to agree to surrender arms, give up most of their navy, and evacuate the territory. (McCormick)