World War I involved one group of countries fighting another.
The Central Powers ( Mittelmächte Központi hatalmak İttifak Devletleri or Bağlaşma Devletleri Централни сили Tsentralni sili ) , consisting of Germany , , the Ottoman Empire and Bulgaria -- hence also known as the Quadruple Alliance ( Vierbund ) -- was one of the two main factions during World War I ( 1914 -- 18 ) . World War I . On 4 November 1918 , the Austro-Hungarian empire agreed to an armistice , and Germany , which had its own trouble with revolutionaries , agreed to an armistice on 11 November 1918 , ending the war in victory for the Allies .