What nation was not ally of great Britain during world war 1?

The Central Powers were one of the two warring factions in World War I (1914-18), composed of Germany, Austria-Hungary, the Ottoman Empire and Bulgaria. This alignment originated in the alliance of Germany and Austria-Hungary, and fought against the Allied Powers that had formed around the Triple Entente. The Central Powers regarded the assassination of Austro-Hungarian Archduke Francis Ferdinand by several militants as being an act supported by the Kingdom of Serbia, and given an unwillingness of Serbia to fully comply with Austro-Hungarian demands for a full investigation of Serbian complicity in the assassination, war between Austria-Hungary and Serbia was justified. This resulted in war with Russia, which opposed Austro-Hungarian intervention and supported Serbia, and ignited several alliance systems to bring the major European powers into a major war.