World War I: The Central Powers capture Bucharest.

The Central Powers, also known as the Central Empires, was one of the two main coalitions that fought World War I (1914–18). It consisted of German Empire, Austria-Hungary, the Ottoman Empire and Kingdom of Bulgaria and was also known as the Quadruple Alliance. Colonies of these countries also fought on the Central Powers' side such as German New Guinea and German East Africa, until almost all of their colonies were occupied by the Allies.

The Central Powers faced and were defeated by the Allied Powers that had formed around the Triple Entente. The Central Powers' origin was the alliance of Germany and Austria-Hungary in 1879. Despite having nominally joined the Triple Alliance before, Italy did not take part in World War I on the side of the Central Powers. The Ottoman Empire and Bulgaria did not join until after World War I had begun, even though the Ottoman Empire had retained close relations with both Germany and Austria-Hungary since the beginning of the 20th century.