In case of what country's attack was the origins of the Central Powers?
Dual Alliance (1879) The Dual Alliance was a defensive alliance between Germany and Austria-Hungary, which was created by treaty on 7 October 1879 as part of Bismarck's system of alliances to prevent or limit war. The two powers promised each other support in case of attack by Russia. Also, each state promised benevolent neutrality to the other if one of them was attacked by another European power (generally taken to be France, even more so after the Franco-Russian Alliance of 1894). Germany’s Otto von Bismarck saw the alliance as a way to prevent the isolation of Germany and to preserve peace, as Russia would not wage war against both empires.
Soviet invasion of Manchuria The Soviet invasion of Manchuria, also known as the Manchurian Strategic Offensive Operation ("Манчжурская стратегическая наступательная операция" , lit. "Manchzhurskaya Strategicheskaya Nastupatelnaya Operaciya") or simply the Manchurian Operation ("Маньчжурская операция"), began on 9 August 1945 with the Soviet invasion of the Japanese puppet state of Manchukuo. It was the last campaign of the Second World War, and the largest of the 1945 Soviet–Japanese War which resumed hostilities between the Union of Soviet Socialist Republics and the Empire of Japan after almost six years of peace. Soviet gains on the continent were Manchukuo, Mengjiang (Inner Mongolia) and northern Korea. The Soviet entry into the war and the defeat of the Kwantung Army was a significant factor in the Japanese government's decision to surrender unconditionally, as it made apparent the Soviet Union would no longer be willing to act as a third party in negotiating an end to hostilities on conditional terms.