Some of the most important dates in World War I include: July 28, 1914 when Austria-Hungary declared war on Serbia, officially signalling the start of WWI; Aug. 1 and 3, 1914, when Germany declared war on Russia and France respectively; and Aug. 4, when the U.K. declared war on Germany. Another important date was June 28, 1919, when the Treaty of Versailles was signed to end the war.
Soon after the U.K. declared war on Germany, Austria-Hungary declared war on Russia, and Serbia declared war on Germany on Aug. 6. Later that month on Aug. 19, the U.S. announced their intention of remaining neutral, which would last until April 6, 1917 when the U.S. declared war on Germany.
There were a few other key dates that year as well, such as: March 15, when Russia's Czar Nicholas II gave up his throne; Nov. 7, when the Bolsheviks overthrew the Russian government; and Dec. 17, when the peace accord between Russia and the Central Powers went into effect.
During the following year, Russia officially signed a peace treaty with the Central Powers on March 3, while on Nov. 9, Germany's Kaiser Wilhelm II gave up his throne. Two days later on Nov. 11, Germany signed an armistice agreement in France to officially end the fighting.