The Northeast Anti-Japanese United Army was the main anti-Japanese guerrilla army in Northeast China (Manchuria) after the Japanese invasion of Manchuria in 1931. Its predecessors were various anti-Japanese volunteer armies organized by locals and the Manchuria branches of the Communist Party of China (CPC). In February 1936, the CPC, in accordance with the instructions of the Communist International, issued The Declaration of the Unified Organization of Northeast Anti-Japanese United Army and marked the official formation of the organization.