Central Powers

Its core was the German-Austro-Hungarian alliance of 1879, which became the Triple Alliance when Italy joined in 1882. In 1914, however, Italy held that the defensive alliance did not oblige it to join a war started by Austria-Hungary, declared neutrality and in 1915 went over to the Entente. The Ottoman Empire signed a secret alliance with Germany on 2 August 1914 and entered the war that autumn, and Bulgaria joined them in September 1915. The four allies were also called the Quadruple Alliance.

The Central Powers defeated Serbia, Montenegro and Romania, and in 1918 made peace at Brest-Litovsk with the Ukrainian People's Republic and Bolshevik Russia. On 5 November 1916 Germany and Austria-Hungary proclaimed a Kingdom of Poland on the lands taken from Russia, hoping for Polish recruits. In autumn 1918 the alliance fell apart: Bulgaria, Turkey, Austria-Hungary and Germany signed armistices one after another.