World War I, also known as the Great War, lasted from 1914 to 1918 and involved many of the world's great powers. The conflict began after the assassination of Archduke Franz Ferdinand of Austria-Hungary, leading to a complex web of alliances and military mobilizations. Major battles occurred on the Western Front and the Eastern Front, with countries like Germany, France, and Britain playing significant roles. The war ended with the signing of the Treaty of Versailles in 1919, which imposed heavy reparations on Germany and redrew national borders in Europe. The conflict resulted in an estimated 16 million deaths and set the stage for political changes and social upheaval, ultimately contributing to the rise of World War II.