The causes of World War I are nebulous. At the time, European foreign policy was a tangle of alliances, imperialist rivalries, nationalist chauvinism, and xenophobia mixed with memories of old slights and humiliations between nations. The last general war in Europe had taken place 99 years earlier with the defeat of Napoleon.
The event that served as the catalyst to the war was the June 28, 1914, assassination of the heir to the Austro-Hungarian throne, Archduke Franz Ferdinand, and his wife, Sophie, Duchess of Hohenberg, who were making an official visit to Sarajevo, the capital of Bosnia. On July 28, 1914, Austria declared war on Serbia, reassured of the support of their German allies.
Over the next few days European diplomacy broke down, the major powers mobilized their armies, and the continent was divided into armed camps. Russia sided with Serbia, and France and Great Britain sided with their ally, Russia. Germany declared war on Russia on August 1 and France on August 3. On the following morning, Germany also declared war on Belgium in order to send troops through Belgian territory on their way to France. Great Britain, which, with Prussia, France, Russia, and Austria, had guaranteed Belgium's neutrality in 1839, had pledged to support Belgium if it was invaded by Germany and resisted. Germany's invasion and Belgium's resistance brought the British into the war on August 4. Thus, Germany and Austria-Hungary supported by Turkey, became the major Central Powers; the major Allied Powers were Great Britain, France, and Russia from 1914 until the Bolshevik Revolution ended Russia's participation in late 1917, by which time the United States had abandoned its neutral stance and had entered the war on the Allied side.
The Great War finally ended on November 11, 1918, when the Allies forced Germany to agree to an armistice. In January 1919 peace negotiations began in Paris, led by the "Big Four": Woodrow Wilson, president of the United States; David Lloyd George, prime minister of Great Britain; Vittorio Orlando, premier of Italy; and Georges Clemenceau, premier of France. Wilson insisted upon shaping the peace treaties according to the "Fourteen Points" he had produced the year before, an idealistic plan for "Peace Without Victory." This plan, to include freedom of the seas, open covenants between nations, self-determination for the subject peoples of the now-defunct Central Powers, and a reduction of armaments, was at odds with the postwar aims of the other Allied Powers, who were more concerned with containing Germany than with noble causes. Wilson's 14th point, a "general association of nations," led to the creation of the League of Nations.
In the long run, the resulting Versailles Treaty with Germany was almost entirely selfdefeating. While it was only one of the five peace treaties negotiated between the Allies and the former Central Powers, it was arguably the most important. The harsh terms dictated to Germany in the Versailles Treaty were a major factor in the subsequent rise of Adolf Hitler and the outbreak of World War II.
Image: 1918, from the National Archives