'Operation 101' was a Japanese naval air offensive against Chunking and other areas of Szechuan province held by the Chinese Nationalist forces of Generalissimo Chiang Kai-shek (1 May 1940).
On this date warplanes of the Imperial Japanese naval air force began to attack Chungking and Chinese air support points in Szechwan province. The attacking formations were the 1st Combined Air Group and 2nd Combined Air Group, using 120 Mitsubishi G3M 'Nell' long-range medium bombers, and these directed their initial effort against the airfields at Hankou and Hsia-Kan.
'Operation 101' was part of the terror bombing campaign against Chungking between 18 February 1938 and 23 August 1943 undertaken by both the Imperial Japanese army and navy air forces with the object of breaking the will of the Chinese Nationalist government, based in Chungking, and the people of Nationalist China. The Japanese campaign was authorised directly by the Imperial General Headquarters in Tokyo.
A conservative estimate places the number of bombing sorties at more than 5,000, in which more than 11,500 bombs, mostly of the incendiary types, were dropped. The targets were usually non-military residential areas, business areas, schools and hospitals (non-military targets). Thus, in accord with the Japanese concept of strategic air warfare, the bombing was focused almost entirely on the civil population, an early example of terror bombing.
In the first two days of the campaign, the raids of May 1939 killed more than 5,000 Chinese civilians. Two months later, after tens of thousands of deaths and largely in retaliation for the Japanese firebombing effort, the USA embargoed the export of aircraft parts to Japan, thus imposing its first economic sanction against Japan. On 5 June 1941, the Japanese flew more than 20 sorties, bombing the city for three hours, and about 4,000 residents who hid in a tunnel were asphyxiated.
Most of the air raids were flown by squadrons of G3M, Mitsubishi Ki-1, Fiat BR.20 Cicogna 'Ruth', Mitsubishi Ki-21 'Sally' and Kawasaki Ki-48 'Lily' warplanes, though later in the campaign these were supplemented by more modern aircraft such as the Mitsubishi G4M 'Betty', Nakajima Ki-49 Donryu 'Helen', Yokosuka P1Y Ginga 'Frances' and Mitsubishi Ki-67 Hiryu 'Peggy'. In the early stages of the campaign the Chinese Nationalist air force was at a notably low ebb of strength, and many of the air raids were totally unopposed.
Some 3,000 tons of bombs were dropped in Chungking between 1939 and 1942, and the campaign eventually totalled 268 separate air raids. Under the supervision of General the Prince Higashikuni Naruhiko, Field Marshal Hajime Sugiyama and Admiral Takijiro Onishi, the Japanese campaign killed more than 10,000 civilians and destroyed 17,600 building in Chungking, and in efforts to beat off the raids the Chinese Nationalists lost large numbers of aircraft.