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Stalemate Develops Outside Paris (September 1914)
Description: After the German advance through Belgium and northern France (as part of the Schlieffen Plan), the Allies halted their progress at the First Battle of the Marne. This led to a prolonged stalemate and the establishment of trench warfare on the Western Front.
Significance: The stalemate signaled the failure of Germany’s plan for a quick victory and marked the start of a long, grueling war of attrition. -
Assassination of Francis Ferdinand (June 28, 1914)
Description: Archduke Franz Ferdinand of Austria-Hungary and his wife, Sophie, were assassinated in Sarajevo by Gavrilo Princip, a Bosnian Serb nationalist associated with the Black Hand group.
Significance: This event is widely regarded as the spark that ignited World War I. Austria-Hungary issued an ultimatum to Serbia, and the failure of diplomacy led to the outbreak of war in late July 1914. -
Lusitania is Sunk (May 7, 1915)
Description: The British ocean liner RMS Lusitania was torpedoed by a German U-boat off the southern coast of Ireland. Among the nearly 1,200 victims, 128 were American citizens.
Significance: The sinking of the Lusitania caused outrage in the United States and increased anti-German sentiment. Although the U.S. remained neutral at the time, this event planted the seeds for eventual American involvement in the war. -
Russian Revolution Removes the Czar (March 1917)
Description: The February Revolution in Russia (March in the Gregorian calendar) forced Tsar Nicholas II to abdicate, ending centuries of Romanov rule. A provisional government was established.
Significance: The revolution marked the collapse of the Russian monarchy and weakened Russia's war effort. Later that year, the Bolsheviks would seize power, leading to Russia's withdrawal from the war and the Treaty of Brest-Litovsk. -
Germany Resumes Unrestricted Submarine Warfare (February 1, 1917)
Description: Germany announced that it would resume unrestricted submarine warfare, targeting any ship, including neutral ones, in the waters around Britain.
Significance: This decision was a gamble by Germany to cut off Allied supplies, but it also directly threatened the United States' neutral shipping. It was one of the key factors pushing the U.S. toward entering the war. -
United States Declares War (April 6, 1917)
Description: The United States formally declared war on Germany following a series of provocations, including unrestricted submarine warfare and the Zimmermann Telegram, which revealed German plans to ally with Mexico against the U.S.
Significance: U.S. entry into the war provided much-needed manpower, resources, and morale to the Allies, tipping the balance against the Central Powers. -
The Armistice Ends the Fighting (November 11, 1918)
Description: An armistice was signed between the Allies and Germany, bringing an end to the fighting on the Western Front. It went into effect at 11 a.m. on November 11, 1918.
Significance: This marked the end of World War I combat operations. However, it was not a formal peace treaty, and negotiations for a final settlement continued. -
Versailles Treaty is Signed (June 28, 1919)
Description: The Treaty of Versailles was signed by Germany and the Allied Powers, officially ending World War I. The treaty imposed harsh reparations on Germany, reduced its military, and redrew the map of Europe.
Significance: The treaty’s punitive terms sowed resentment in Germany and contributed to economic hardship and political instability, which eventually led to World War II.