showing bombs from IJAAF Type 97/Ki-21 (九七式重爆撃機) heavy bombers exploding on
Yuzhong Peninsula In the first two days of the
Operation 100 (
100号作战) bombing campaign, 54 and 27 Japanese bombers raided Chongqing on 3 and 4 May 1939 respectively, dropping approximately a 3:2 ratio of
Type 98/25 high explosive "land bombs" (98 dropped on day one) and Type 98/7
incendiary bombs (68 dropped on day one). The first raid killed almost 700 residents and injured 350 more. Major Deng Mingde led the
22nd Pursuit Squadron (of the 4th Pursuit Group) Polikarpov fighters against the bombers on 3 May, shooting down seven bombers but losing two pilots including his deputy commander, the veteran Zhang Mingsheng. Zhang tried to save his damaged plane, but it became engulfed by fire, and while bailing-out and parachuting to safety, he was severely burned; he was then attacked by locals who thought he was a Japanese airman as he laid on the ground, barely able to mutter a sound to identify himself, and rescued four hours later, succumbing to his battle wounds the following day in a hospital. The pre-dawn attack on 4 May resulted in far more casualties, with over three thousand deaths, injuring almost 2,000 more, and leaving about 200,000 homeless. Although the attacking force was smaller and dropped fewer bombs, there was no interception of the bombers by the Chinese Air Force whose airbases in the Chongqing region were not yet set up for nighttime operations. Two months later, after tens of thousands of deaths, in retaliation for
firebombing, the United States embargoed the export of airplane parts to Japan, thus imposing its first
economic sanction against that nation. The Japanese began to embark more nighttime bombing raids against Chongqing in summer of 1939 in an effort to reduce confrontation and casualties from defending Chinese Air Force fighters; however, the Chinese pilots began operating nighttime interceptions over Chongqing with some success in shooting down the nighttime bombers using "lone wolf" fighter tactics previously deployed during the
Battle of Nanking two years earlier (and similar to the
Wilde Sau tactics the Luftwaffe would deploy a few years later). The interceptions involved the coordination with a series of manually operated ground-based searchlights illuminating and tracking incoming bombers which can then be seen and targeted by the solitary fighter pilot; fighter ace
Liu Zhesheng shot down a bomber on the night of 3 August 1939 flying "lone wolf" in an I-15bis during such a nighttime interception mission over Chongqing, among several other kills he claimed while battling for the defense of Chongqing. In the following night, Capt.
Cen Zeliu would also claim a nighttime kill of a bomber while at the controls of an I-15bis. Monks of the Ciyun Temple contributed greatly to rescuing and saving lives of residents over the course of the half-decade-long bombing campaigns over Chongqing. By mid-1940, the IJNAF G3M Model 21 bombers that formed the primary aircraft of the
carpet-bombing campaign against Chongqing and Chengdu had become largely relegated to nighttime bombing attacks, while daylight raids were being replaced with the new and improved Model 22/23 G3Ms equipped with the higher-octane rated and supercharged
Kinsei 51 engines, boosting the power of each of the twin-engined bombers by 500 horsepower and greatly enabling the
schnellbomber strategy further above the general obsolescence of the defending Chinese fighter aircraft now struggling to gain speed and altitude to make even a single head-on pass against the high-speed/high-altitude IJNAF bombing runs, and even more vulnerable to the massed-firepower of those heavy bomber formations. Also by mid-1940, the Japanese had employed new tactics to stave off attacks from defending Chinese fighters; the Chinese air raid early warning network would alert the Chinese fighter squadrons to scramble their fighters towards approaching Japanese bomber formations (ideally with ample time to attain sufficient altitude ahead of the raids); however, they were being monitored by fast IJNAF
C5M (IJAAF designation
Ki-15) scouting-attack planes at high altitudes which would radio instructions to the bombers to circle out of range as the Chinese fighters rose to meet the bombers; once the Chinese fighters had run low on fuel and returned to base, the scouts would then redirect the bombers to attack the Chinese fighters on the ground refueling. While the Chinese soon cracked the code used by the C5M crews relaying messages to the bomber formations, some of the countermeasures used by the Chinese pilots were to launch a pair of I-16s that were almost fast enough to intercept the C5M in pursuit, but enough to force the scouts away, while a second flight of fighters were launched against returning Japanese bombers as the first flight of Chinese interceptors returned to disperse in smaller auxiliary airbases to refuel, although successful interceptions were still limited against the IJNAF bombers as the Polikarpovs struggled in particular against the new Model 22/23 G3M bombers. The Japanese air raids against Chongqing had become increasingly intense and destructive as the "joint air strike force" of the Imperial Japanese Army and Navy bomber formations began to comprise upwards of 150–200 bombers per raid, under the new codename "Operation 101" (
101号作战), and massed defensive machine gun and cannon fire from the bomber formations were very effective against the slow Chinese fighter aircraft further handicapped with burning low-grade fuel, much of which came by way of
French Indochina and processed locally; locally sourced oil came by way of the
Yumen Laojunmiao oil wells in
Gansu province beginning in the summer of 1939, which produced 90% of the native petrol (250,000 tons) for China during those war years. The Japanese warned foreign delegations in Chongqing to avoid being hit as
collateral damage in the massed attacks by moving to pre-defined "secure areas" which would be exempt from bombing; a large
Nazi flag was emblazoned on the roof of the German embassy in Chongqing, but was still hit by a Japanese air raid. who represented the Imperial Japanese Army Air Service during the
Operation 101 and
102 joint-strike bombing campaigns, led a targeted aerial-assassination strike on Generalissimo Chiang Kai-shek on 30 August 1941; he would put forth his "
Futility of the Chongqing Bombing Thesis" (重慶爆擊無用論) days after the failed assassination strike, and gained a reputation as a post-war anti-war pacifist, establishing the ''China-Japan Servicemen's Devotion Society'' (日中友好军人协会) Following the
defeat of France by Germany in June 1940, the French
Vichy Government submitted to the demands of the Japanese – allowing Japanese troops to conduct cross-border raids into Yunnan province, and the stationing of Japanese army air units at three airbases in
French Indochina (now
Vietnam), including
Lạng Sơn. On 10, 12 and 16 June 1940, the Japanese raided Chongqing with 129, 154 and 114 bombers on these days respectively, while the Chinese I-15 and I-16 fighter squadrons engaged these attacks shooting down 13 of the raiders, perhaps more importantly, forcing bombers to miss their targets, although these disrupted flights of bombers may have evaded the Chinese fighters from their primary targets, and diverted out to drop bombs on secondary targets, including other large population and industrial areas such as
Ziliujing and
Luxian. The Chinese would be dealt with a serious blow a few weeks later in July 1940 when the British yielded to Japanese diplomatic pressure and closed the
Burma Road, which was China's primary lifeline for material and fuel needed in the defense of Chongqing and Chengdu. On 11 August 1940, 4th PG CO Maj.
Zheng Shaoyu personally selected a team of five of his top fighter pilots, including ace fighter pilot Capt. Liu Zhesheng and future ace Lt.
Gao Youxin to deploy a new weapon in an experiment to help with the dispersal of, and attacks against, the massive Japanese bomber formations: multiple
air burst bombs developed by combat flight instructor Yan Lei of the
Central Air Force Academy at the
Wujiaba Airbase. At 13:56 hours that day, 90 G3M bombers appeared in two waves, and Maj. Zheng's team, with ample preparations, maneuvered high and above the approaching bomber formation with precision flying while the Japanese aircrews observed the unusual movements of the Chinese fighters, who soon dropped the air-burst devices that descended under parachutes, and detonating just a few hundred meters in front of the lead bombers, resulting in a breakup of the bomber formation followed by furious attacks from the Chinese fighter pilots the best they could with the handicap of the highly challenged performance and firepower of their Polikarpovs, claiming five shot down (two wrecks confirmed) and damaging many others; eight Chinese fighters suffered various degrees of damage while the wreckages of Japanese bombers were found in Shichuxian and Shuangqing with three of the seven-man crew in one of the bombers found alive and taken prisoner. The state-of-the-art new Japanese Mitsubishi A6M
Zero fighters were first deployed into combat in course of the Chongqing and
Chengdu bombing raids, and received its first baptism of fire in aerial combat on 13 September 1940; 13
Zeroes of the
12th Kokutai led by Lieutenant
Saburo Shindo which had escorted 27 G3M bombers on a raid into Chongqing were sent against 34 Chinese fighters: including Polikarpov I-15bis (led by Maj.
Louie Yim-qun of the 28th PS) and I-16 (led by Capt. Yang Mengjing of the 24th PS) and other Polikarpov fighters of Maj. Zheng Shaoyu's 4th PG. The battle lasted about half an hour by which point the Chinese were low on fuel and had to break off; with some luck, escaping further contact with the much faster Zeroes. Many of the Polikarpovs were damaged or shot down (the Zero pilots claiming "all 27 Polikarpovs" shot down), with ten pilots killed, and eight wounded, Maj. Zheng Shaoyu and Lt. Gao Youxin managed to drive Zeroes off the tails of other Chinese fighters, with Lt. Gao closing-in to 50 meters (160 ft) of one, and claiming a Zero shot-down, but in fact only four Zeroes suffered some damage, and all 13 safely returned to base in Wuhan. leaning on an
I-15bis, the plane he flew against the A6M ''Zero's
debut air-battle on 13 September 1940, fighting-off numerous attacks by the confounding performance of the new air-superiority fighter, and surviving; Xu would exact a measure of personal revenge on 4 March 1944 when he shot down an A6M Zero'' over the Japanese airbase at
Qiongshan,
Hainan, whilst flying a
P-40 Warhawk with the
CACW As the already desperate situation was now irrefutable with the scourge of the new Zero fighters, In response to the
Japanese invasion of French Indochina, the Empire of Japan was finally met with the
U.S. scrap metal and oil embargo against Japan and the freezing of Japanese assets in summer of 1941. On 5 June 1941, in midst of the increased brutality of the new Operation 102 bombing campaign to force the Chinese to capitulate in their war of resistance, the Japanese flew more than 20 sorties, bombing the city for three hours. About 4,000 residents who hid in a tunnel were
asphyxiated. With the start of
full-scale war between the Soviet Union and Nazi Germany on 22 June 1941, and with Generalissimo Chiang Kai-shek looking for increased support from the Americans through the Lend-Lease Act of which was extended to China on 6 May 1941, all new fighter aircraft produced by the Soviets were now directed to the battlefronts against Nazi Germany. On 11 August 1941, in what would be the last-recorded dogfight between the Chinese Air Force fighters and the IJNAF
Zeroes before all active
Zero squadrons were pulled out of China in preparations for
Operation Z (the preparation for the Pearl Harbor attack mission), future Japanese ace-fighter pilots
Gitaro Miyazaki and
Saburō Sakai were part of the escort of an
Operation 102 bomber attack and fighter sweep of Chinese air bases between Chongqing and Chengdu, and encountered Chinese I-153 and I-16 fighters at Wenjiang Airbase; while shooting down all those that managed to take off or strafing those still taxiing down the runways, Saburo Sakai described how five Zeroes then struggled to shoot down the one last opponent still in the air that "was an absolute master" as it "snap-rolled, spiralled, looped and turned through seemingly impossible maneuvers... like a wraith", but Sakai himself only managed to finally shoot down the acrobatic biplane fighter pilot when he was forced to slow-roll in a climb while trying to clear over the top of a hill west of Chengdu. The belly of the Chinese fighter suddenly exposed right into the gunsight of Sakai's Zero, who fired cannon shells that "tore through the floorboards of the biplane", sending it down in a wide spin and exploding as it hit the hillside. As Japan's focus shifted towards the
Pacific campaign, and much of the Japanese aerial-combat assets and experienced personnel had been diverted to support the war in the Pacific, the offensive campaign against Chongqing and Chengdu had been significantly curtailed; nonetheless, modern interceptor aircraft possessing far greater speed and firepower, supported by ground-based radar equipment, and new aircrew training supported by the US and Allied partners, allowed the Chinese Air Force to be in a much better position to fight back by August 1943. The last recorded air raid of the campaign took place on 19 December 1944. ==Total bomb tonnage and raids==