World War I lasted from 1914 to 1918 and gave rise to a level of destruction and death never before seen in the modern war, mostly due to the combination of the tactics of trench warfare and modern military technology. By the time the armistice was finally reached, more than 18 million lives had been lost.
Why World War I Happened
While general unrest in Eastern Europe and the Balkan territories was causing strife on the continent, the true catalyst for World War I was the assassination of Archduke Franz Ferdinand at the hands of a Bosnian student who was part of the Serbian Nationalist movement. Austria-Hungary, once assured of support from Germany with whom they had a mutual defense pact, struck at Serbia and was met with retaliation from Russia, Serbia's wartime ally. Soon, the conflict had expanded to include Britain, France, Japan and the United States.
World War I Timeline
June 1914 – Archduke Franz Ferdinand and his wife, Sophie, are assassinated in Sarajevo by Bosnian student Gavrio Princip. Austria subsequently declares war on Serbia.
August 1914 – Germany declares war on France and invades Belgium.
October 1914 – Trench warfare is rampant in Western Europe.
January 1915 – The first of several zeppelin raids on Britain takes place.
May 1915 – A German U-boat sinks the ocean liner Lusitania.
February 1916 – The Battle of Verdun takes place.
September 1916 – Tanks are used en masse in the battle of Somme.
February 1917 – Germany attacks merchant ships and other nonmilitary seafaring vessels despite warnings from the United States and Britain.
April 1917 – The United States officially declares war on Germany.
November 1917 – British troops win a victory at Cambrai.
March 1918 – Russia and Germany sign the treaty of Brest-Litovsk.
August 1918 – The Allied powers advance successfully across Europe.
October 1918 – Germany requests armistice; Germany's navy mutinies.
November 1918 – Armistice is reached; the war ends.
United States in World War I Timeline
When the war first broke out, the United States, under President Woodrow Wilson, had pledged to remain neutral as was the United States' custom in European wars. However, the United States had allyship with Britain, and when Germany declared its intentions to sink ships traveling in the Atlantic, the United States warned them against sinking any boats that weren't warships. Germany sunk the Lusitania, an ocean liner carrying weapons to Britain in 1916. Though Wilson was campaigning for re-election on the slogan "He Kept Us Out of War," there was increasing tension with Germany, who had begun to sink merchant ships and munitions boats despite warnings. In 1917, Germany sank four U.S. merchant ships, and Wilson asked Congress to declare war. The United States officially entered World War I on April 6, 1917.