Assassination of Archduke Franz Ferdinand of Austria in Sarajevo, the provincial capital of Bosnia- Herzegovina(formally annexed by Austria-Hungary in 1908), by Gavrilo Princip, a Bosnian Serb nationalist.This event set in motion diplomatic crises and a series of events leading to the outbreak of world War 1.
The war primarily involved Europe's great powers,which ultimately assembled into two opposing military alliances: the Central Powers principally centered around Germany and Austria-Hungary and allied with the Ottoman Empire and the Allied powers,which formed around France , the Russian Empire,the United Kingdom, Italy,Japan, and the United States.These alliances were reinforced by the secret treaties which committed each to go war should any one nation be attacked.
World War I came to an end on November 11, 1918, when an armistice between Allies and Germany went into effect. The war had lasted for four years and had claimed the lives of millions of people.The immediate trigger that led to the armistice was Germany's decision to seek peace negotiations. This decision was made in response to several factors including the Allies successful military advances, the worsening economic conditions in Germany ,and the growing unrest among German civilians.
The armistice agreement was signed on November 11,1918. Although the armistice officially ended the fighting, it was not until the signing of the Treaty of Versailles in 1919 that the war was formally concluded. The treaty placed the blame for the war solely on Germany and required Germany to pay reparations and to cede territory to the Allied Powers. The treaty also established the League of Nations, an international organization aimed at preventing future wars.