Imperial Japanese Army Air Service
During the Manchurian Incident of 1931, the Japanese widely used airplanes to indiscriminately bomb key targets and cities, such as Mukden. After the Marco Polo Bridge Incident, the Imperial Japanese Army Air Service, in conjunction with the Imperial Japanese Navy Air Service, began relentlessly bombing Shanghai, Beijing (Peking), Tianjin (Tientsin) and several cities on the Chinese coast from the beginning of the Second Sino-Japanese War in 1937.