In case of what country's attack was the origins of the Central Powers?
Central Powers The Central Powers (German: "Mittelmächte" ; Hungarian: "Központi hatalmak" ; Turkish: "İttifak Devletleri" or "Bağlaşma Devletleri" ; Bulgarian: Централни сили "Tsentralni sili" ), consisting of Germany, Austria-Hungary , the Ottoman Empire and Bulgaria – hence also known as the Quadruple Alliance (German: "Vierbund" ) – was one of the two main factions during World War I (1914–18). It faced and was defeated by the Allied Powers that had formed around the Triple Entente. The Powers' origin was the alliance of Germany and Austria-Hungary in 1879. The Ottoman Empire and Bulgaria did not join until after World War I had begun, although the Ottoman Empire retained close relations with both Germany and Austria-Hungary since the beginning of the 20th century.
Berlin Memorandum The Berlin Memorandum was a document drawn up by the three imperial world powers in 1876 to address the Eastern Question during the Crisis of 1875-1878. The purpose of the Berlin Memorandum was for the three imperial powers of Russia, Austria-Hungary, and Germany to address the state of relations between the Islamic Ottoman Empire and with the Christian peoples of the Balkans, with whom these imperial powers had international relationships and interests, and to correct the "Andrássy Note", a document that preceded the Berlin Memorandum and had similar intentions in creating an armistice and plan of reforms for the Balkans and the Ottoman Empire.