For many years rival groups of European nations had been making treaties and alliances. By 1914 Europe had been divided into two camps. Germany, Austria-Hungary, and Italy were members of the Triple Alliance.
Later, after the withdrawal of Italy and the addition of Turkey, the Triple Alliance took a new name, the Central Powers. Russia, France, and Great Britain had formed the rival Triple Entente. Later they were called the Allies. Except for Bulgaria, the Balkan states sided with Serbia and the Allies.
These alliances were brought into action by Austria-Hungary’s declaration of war. Within a week most of Europe was at war. Using the Schlieffen Plan, Germany planned to conquer France first and then quickly move troops east to defeat Russia. The strategy failed when the British army joined France and blocked the Germans’ advance before they reached Paris.
Trench warfare reached its height during the war. Troops fighting for the Allies and Central Powers dug complex networks of trenches into the ground for use in making attacks or defending themselves.
The November 11 Armistice between Germany and the Allies ended the fighting, and negotiations for peace began. The Paris Peace Conference began in January 1919 in Paris. The conference inaugurated the international settlement after World War I.
A major product of the Paris Peace Conference was the Treaty of Versailles, signed in June 1919 at the Palace of Versailles in France. Under the agreement, Germany was forced to accept blame for Allied losses and to pay major reparations. Also formulated at the Paris Peace Conference was the League of Nations, an organization for international cooperation established by the Allies.