World War I, a major conflict that took place from 1914 to 1918, involved many of the world's great powers divided into two opposing alliances: the Allies and the Central Powers. Triggered by the assassination of Archduke Franz Ferdinand of Austria, the war was characterized by trench warfare and significant loss of life. Innovations in weaponry and tactics led to unprecedented destruction and suffering. The Treaty of Versailles formally ended the war in 1919, imposing harsh penalties on Germany and reshaping national borders in Europe. The war had lasting effects on global politics and society.