Japan's invasion of Northeast China began with the Sino-Japanese War of 1894. After the Russo-Japanese War in 1905, Japan took over the operation of the Liaodong Peninsula and the South Manchuria Railway from Changchun to Lushun from Russia, and began its 40-year colonial rule of Northeast China. After Japan surrendered in August 1945, the Kwantung Army headquarters issued a secret order to destroy incriminating evidence in an attempt to erase the traces of aggression from the earth. However, due to the hasty evacuation, a large number of military facilities, chemical weapons, archives, etc. Are still abandoned in various parts of Northeast China, forming many mysteries that remain unsolved to this day.
