Zhu Jia-Xun was originally trained by Japanese Army instructors in the Kwangsi Provincial Air Force in China and became a deputy squadron commander of the 8th Pursuit Squadron (PS) of the 3rd Pursuit Group (PG) when the Kwangsi Air Force was incorporated into the Central Chinese Air Force.

On 18 March 1938, the 3rd PG was ordered to strafe and bomb Japanese Army positions around Teng Hsien near Hsuchow on the Northern Front. The 3rd PG commander Lieutenant Colonel Wu Yu-Liu led ten I-15bis from the 7th PS at Hsiao-Kan and 8th PS from Hsinyang to the forward base at Chu-Ma-Tien to refuel and arm with two 10kg bombs. After refuelling again at Kuei-Teh airfield, the group proceeded to the target area where they bombed and strafed Japanese positions during a Chinese Army counter-attack.
On their return journey, Zhu spotted two Japanese Army Air Force (IJAAF) Type 93 twin-engine heavy bombers of the 6th Daitai (Group) on a reconnaissance mission. He single-handed attacked one of the bombers flown by Captain Saburo Towata and sent it crashing in flames, killing all onboard. The remaining bomber was set upon by the other Chinese fighters and badly shot up. The Japanese pilot Lieutenant Muto managed to crash-land his stricken aircraft but out of the crew of four, one gunner was killed and the rest wounded. During the action, other Chinese pilots spotted a Type 88 reconnaissance plane of the IJAAF 1st light bomber daitai of the 16th Hiko Rentai and shot it up, killing the observer and forcing it to crash land in no-man's land.
Three Chinese I-15bis were damaged; Lieutenant Colonel Wu Yu-Liu's no. 5897 was damaged by return fire during the action with the two bombers. He force-landed just short of the Kuei-teh airfield. The 7th PS commander Captain Lu Tien-Lung's aircraft was hit 30 times by ground fire while chasing the Type 88 but returned safely. Two other 7th PS aircraft, Lieutenant Ou-Yang Shen's no. 5867 and Lieutenant Chou Chun's no. 5869 were also damaged by ground fire. Ou-yang had his left ring finger shot off and had to force-land near Chinese positions near Hsu-Chow. He flew, however, back to base the following day.

On 10 April Zhu was again in action in the same Hsuchow area. In an earlier action on 25 March, the 3rd PG had lost six I-15bis and three pilots killed when they were attacked by 19 Kawasaki Type 95 (Ki-10) biplane fighters of the JAAF 2nd Daitai near Kwei-teh airfield (Koi-toh in Japanese). Zhu was not in that action and was out to avenge his comrades. In this Second Battle of Kwei-teh, the Chinese sent 18 I-15bis from the 3rd and 4th PG to again attack Japanese Army field headquarters at the elementary school in the town of Chao Chuang.
Zhu was flying one of the seven 3rd PG I-15bis led by Major Lin Tsuo. Of the remaining I-15bis five were from the 22nd PS, 4th PG and six from the 23rd PS, 4th PG. The Chinese planes bombed and strafed their target to great effect, setting many fires in the school compound and scattering many Japanese Army horses. On their return journey, the 3rd PG took the high cover position at 4,500m, 500m above the 4th PG aircraft. Near Ma Mu Chi, the lower formation of Chinese aircraft was attacked by three Ki-27s (Nakajima Type 97 monoplane fighters; this was the combat debut of this type) from the 1st chutai, 2nd Daitai, flown by Captain Tateo Kato, Warrant Officer Morita and Sergeant Major Risaburo Saito and 12 Ki-10s (Kawasaki Type 95 fighters) of the 2nd Daitai (HQ flight) led by Major Tamiya Teranishi.
The 3rd PG I-15bis were in a perfect position to "bounce" the Japanese fighters. Zhu caught the Ki-27 of Sergeant Major Saito (NCO50) as it was diving on a 23rd PS I-15bis. Zhu apparently hit the Japanese pilot with his fire and Saito crashed his plane into that of Lieutenant Chen Hui-Min. Chen managed to bail out with a wounded leg but Saito was killed. Afterwards, Zhu was surrounded by a number of IJAAF fighters and his I-15bis was damaged. His engine cowling was shot away but Zhu managed to land his I-15bis safety in a wheat field. Most of the Chinese fighters were already short of fuel when the fighting started, nevertheless, they gave a good account of themselves. In the melee, two other 4th PG I-15bis were shot down, one pilot bailed out and the other was lost. Three other 4th PG aircraft force landed due to damage and fuel starvation but they were recovered. The 3rd PG lost one I-15bis and its pilot. Two, including Zhu, force-landed due to damage or fuel starvation but both aircraft were recovered. Two other 3rd PG pilots were slightly injured by Japanese gunfire but returned to base safely.
As for the IJAAF, in addition to Sergeant Major Saito, one other pilot, Lieutenant Yonesuke Fukuyama died of his wounds. Fukuyama, flying a Ki-10 and despite repeated gun stoppages, managed to claim three Chinese fighters shot down when being heavily engaged together with Sergeant Major Shimokata before being hit and severely wounded in the right arm and left leg. Fukuyama flew part of the way back to Ching Chow airfield while holding the stick with his mouth! He managed to crash-land his plane at the airfield after covering the 200-kilometre flight in 50 minutes. He was immediately removed to hospital but died of his wounds four days later. Two other damaged IJAAF fighters crash-landed back at Ching Chow airfield and two crashed landed at the battlefield. Of the latter, one of the IJAAF pilots was picked up by his wingman who landed in no-man's land between the Chinese and Japanese Armies.
Tokuya Sudo from the 2nd chutai of the 2nd Daitai claimed two I-15bis in this combat while Iori Sakai from the same chutai claimed three victories. Captain Tateo Kato’s 1st chutai of the 2nd Daitai (Ki-27s) fought against eight I-15bis and Kato personally claimed two of the Chinese fighters while Warrant Officer Morita claimed two more.
According to Japanese records fifteen Japanese fighters took part in this combat over Guide claiming 24 victories from 30 encountered while losing two fighters.

On 29 April 1938 (Japanese Emperor Hirohito’s birthday) 18 G3M2s of the 13th Kokutai Japanese Naval Air Force (IJNAF) escorted by 27 A5Ms of the 12th Kokutai under the command of Lieutenant Commodore Y. Ozono attacked Wuhan.
The 4th PG at Hankow Field had nine I-15bis, seven I-16s, and two I-16s from the 24th PS. The Russian volunteers had 23 I-15bis and 16 I-16s. The 3rd Group detachment based at Hsiao Kan was equipped with four I-15bis and six I-15bis were from the 17th PS, 5th PG.
Reconnaissance revealed the Japanese intentions in good time and early in the morning at Nanchang’s aerodromes (there were two) the order went out to all to fly to Hankow in flights, at treetop level (altitude no greater than 25 m). By 08:00 a lot of fighters had concentrated there. By 09:00 all the aircraft had been re-fuelled and the pilots were in the cockpits waiting the order to take off. That day dense clouds at several levels covered the sky, beginning at 2000-2500 m.
The first communications from the air warning system (VNOS) began to be received at 10:00. At 14:00, when the Japanese aircraft approached Wuhan fighters were already waiting in the air with sufficient altitude. According the previously drawn up plans, the I-15bis closed in on the Japanese fighters in a pincer attack while the I-16 formation fell upon the bombers.
Mao Ying-Chu, commander of the 4th PG, led nine I-15bis into the battle. Liu Chi-Han and Liu Chung-Wu took off first and met over a reported 20 Japanese aircraft. They each claimed a Japanese aircraft, as did Yang Shen-Yen. Moments later Liu Chung-Wu claimed a second Japanese aircraft. His aircraft was, however, also damaged in this battle.
Teng Ming-Teh led the I-16s of the 4th PG and 24th PS to patrol the airspace over the airfield. The Russians at first left the formation, but then turned around and joined in the battle near Liang Tze Lake. They claimed six Japanese bombers and seven fighters.
During the combat Lieutenant Chen Huai-Min of the 23rd PS claimed a Japanese plane. His plane was then badly damaged and he rammed another Japanese aircraft and both aircraft exploded in mid-air. Chen was killed.
While the combat was in full swing the four I-15bis of 3rd PG and the six I-15bis of 17th PS arrived overhead at 6500 feet south of Wuhan after that the Japanese bombers had dropped their bombs. They immediately joined combat and Shen Tse-Liu, commander of the 3rd PG detachment severely damaged one Japanese bomber. His vice-commander Li Chia-Hsun and Mo Ta-Yen each downed a Japanese bomber. Zhu Jia-Xun flew the fourth 3rd PG I-15bis. During the combat Zhu claimed to have downed one of the G3M2s south-east of Wuchang. This was near the position where two of the IJNAF G3M2s was downed. Many other Chinese and Russian volunteer pilots also made claims so Zhu should probably only be credited with a "shared" kill.
The Russian volunteer Aleksey Dushin told in his memoirs that they took of early, first Aleksey Blagoveshchenskiy, after him the entire group in established order. The I-15bis were to join battle with the fighters. At a height of about 3000m they moved off from Hankow about 100 km in the direction of Nanking, orienting themselves through the gaps in the clouds by the channel of the Yangtze. Not finding the fighters, on a return course, through gaps in the clouds they discovered a large group of bombers approaching on a parallel course. With a sudden attack at close range they right away set fire to three of the bombers, including the formation leader. The formation immediately fell apart and jettisoned its bombs in a rice paddy. In the air, developed dogfights and in various parts of the sky appeared the torches of burning Japanese aircraft. The “Chizhi” chased after the bombers for their full radius of action - more than 200 km. When his ammunition was completely exhausted Dushin ran into two A5Ms but there was nothing he could do to them. A. S. Zingaev’s group, with an advantageous position attacked a group of Japanese bombers on the approaches to the aerodrome, and in their first attack shot down two (Zingaev shot down the leader). In this combat Grigoriy Kravchenko shot down two (one bomber and one A5M) aircraft. But in the end, he was cut off from his formation and hard pressed by four Japanese who set his aircraft afire. He was saved by Anton Gubenko, who came to his help at the right moment.
Known Russian volunteers known to have claimed in this combat are Blagoveshchenskiy, Dushin, A. Grisenko, Gubenko, Kravchenko (two), I. Puntus, Georgiy Zakharov and A. Zingaev. The major success of the volunteers was explained by the Japanese fighters, which were late at the rendezvous with their bombers, and also by the Soviets’ successful use of the clouds.
AA at Wuchang also fired at the Japanese aircraft over Hanyang and claimed two of them.
A total of 21 Japanese aircraft, 11 fighters and 10 bombers, were claimed shot down in this fierce 30-minute battle and 50 aircrew were killed. Two parachuted and were captured. However, it has only been possible to verify two lost G3M2s.
Twelve aircraft of the Chinese and Soviet volunteers were lost and five pilots killed; identified are Chen Huai-Min, starshiy leytenant Lev Zakharovich Shuster (born 1914) and kapitan Aleksey Yevgen’yevich Uspenskiy (born 1906). Shuster was reportedly killed while colliding with a Japanese aircraft.
The Japanese reported that when their formation appeared over Hankow, a reported 78 I-15s and I-16s rose to intercept. They claimed that in a 30-minute battle they destroyed no fewer than 40 Chinese aircraft while themselves losing only two A5Ms (PO2c Ken-ichi Takahasi (Pilot 19) and PO3c Kinji Fujiwara (Pilot 29) being killed) and two G3M2s. During this combat Motonari Suho claimed his first victory (totally 15 victories – 11 in China) but his own aircraft received hits, however; on the way, back to base he had to make an emergency landing at Anking because he ran out of fuel. Lieutenant Takahide Aioi claimed his first two victories when he shot down two I-15s (totally 10 victories – 5 in China). The Japanese attribute the greatest part of their success to the inexperience of their opponents. In other accounts (also based on Japanese sources), 67 Soviet aircraft participated in the battle, of 19 I-15bis and six I-16s were flown by Soviet volunteers. According to these accounts the Chinese lost nine aircraft and four pilots.
After this fierce combat Japanese did not attack Wuhan for a month.

Zhu served as Squadron Leader of 32nd PS in August 1938. The squadron was at this time equipped with Gloster Gladiator Mk.Is.

At 07:40 on 3 August 1938, 18 G3Ms were seen flying over Guangde. Later at 09:00, more than 70 Japanese fighters were reported heading for Hankou. In response to this treat, the Chinese Air Force scrambled 52 fighters consisting of 20 I-15bis, 13 I-16s, 11 Gladiators and 7 Hawk IIIs in four groups from Hankou to intercept the Japanese intruders. The 11 Gladiators were assigned to the 4th PG, which was divided into two subgroups. Subgroup A was led by Captain Wu Yu-Liu, Commander of the 3rd PG, who was flying an I-15bis and with four Gladiators under his leadership. Subgroup B was led by 28th PS leader Chin Shui-Tin, who was flying Gladiator no. 2809 and with six Gladiators under his leadership.
Subgroup A took off from Hankou at 09:55. Because Wu Yu-Liu's I-15bis not could match the speed of the Gladiators, he was forced to fly astern of the Gladiators and he therefore passed the command to Zhu Jia-Xun, Squadron Leader of 32nd Squadron. As Zhu led the Gladiators to move into the forward position, Wu's I-15bis was attacked by A5Ms. Since the I-15bis was obsolete in comparison to the more nimble Japanese fighters, Wu's situation was most critical but luckily Zhu and his Gladiators returned and attacked the A5Ms. Zhu and He Jermin took charge of the attack while the other Gladiators provided them with cover at a higher altitude. Zhu attacked the two A5Ms chasing Wu's I-15 and one of them abruptly turned and fled while the other was hit by Zhu, who punctured the A5Ms wing tank causing it to lose altitude rapidly. Zhu's wingman, He Jermin, shot down another A5M, which ditched into Lake Chaoping. Totally, Subgroup A was in combat with the A5Ms for more than 10 minutes and they landed at Hankou airbase at 11:30.
Subgroup B was airborne just a few minutes after Subgroup A departed. Chin led the seven Gladiators in a wide orbit in the south-west corner of Hankou climbing to 12000 feet. The height made the Chinese pilots groggy from hypoxia when they suddenly became aware that the sky to their left was speckled with A5Ms. Chin signalled the Gladiators to climb to 21000 feet but the Japanese fighters detected them. Over 30 A5Ms diving from 2000 feet above engaged the seven Gladiators. There were three I-16s from the 1st Air Group (probably from the 26th PS) attached to Subgroup B and these were lagging behind the Gladiators. The attacking A5Ms immediately cut these off. Squadron vice-commander Louie Yim-Qun in Gladiator no. 5732 was flying in the tail end Charlie position and he was attacked simultaneously from different directions but he was relieved by Chin and Shen Mushiu in Gladiator no. 2804. Louie Yim-Qun claimed a shared enemy aircraft destroyed in this combat.
An I-16 under attack from several A5Ms was helped by Chin’s wingman, Fan Hsin-Min in Gladiator no. 2805, who dived to his rescue but he was soon himself under attack from other A5Ms. Chin went to his wingman's aid and managed to shoot the A5M off his tail. Before Chin could deliver the coup de grace to his victim, he came under attack himself. The first indication he got of the attack was bullets bouncing off the newly installed armour plate, which probably saved his life. Chin turned tightly to evade the attack but his Gladiator was already damaged. Three A5M's lined up to making firing passes, diving from above, firing and then zooming back up for altitude, taking full advantage of the A5M's better performance in the vertical plane. After a few passes, Chin’s aircraft was badly shot up, with a number of wing-bracing wires shot away. His aircraft was almost uncontrollable and he decided to take one of the A5M's with him. As one of them completed his firing pass and began his zoom climb, Chin reversed his turn and rammed the A5M. His right wings and nose hit the tail of the A5M and tore it off. Chin’s head was slapped against the side of the canopy of the wildly spinning Gladiator before he was able to bail out. Landing in a field, Chin was presented with a machine gun salvaged from his crashed Gladiator. Hitching a ride back to Hankou in a Douglas O-2MC, Chin was sent to the infirmary when Chennault came to visit him. Chin joked about the machine gun by asking Chennault if he could swap it for a new plane to fight the Japanese. Chennault later embellished the story in "The Way of a Fighter" saying that Chin found the gun, carried it back to the airfield and asked to swap it for a plane. More dramatic but not quite the truth!
A fourth A5M was claimed by Liu Ling-Yang of 28th PS. His own aircraft was however damaged and he bailed out into the Yangtze River and swam to safety.
Subgroup B lost another Gladiator in this combat. This loss was attributed to an engine failure when the engine on Gladiator no. 5723 stopped in the middle of the combat. The Gladiator started to spin and with many difficulties was the pilot, Chou Ling-Hsu, able to get out of the cockpit in time since when he was hanging in his parachute, the Gladiator exploded in mid-air, sending debris flying several thousand feet in all directions.
In this combat claimed the commander of the 26th PS, Captain Wang Han-Hsun, an enemy aircraft before his I-16 was badly hit; in his cabin were more than 60 bullet hits. Liu Ling-Chi (no. 5922) also shot down a Japanese aircraft. When his I-16 was set afire the pilot baled out. I-16 no.5921 was shot down and no. 5920 made a forced landing.
The Japanese escort seems to have been 21 A5Ms, which returned claiming 27 enemy aircraft and 5 probables for the loss of three fighters from the 15th Kokutai (Lieutenant (junior grade) Naohisa Shinjo (Class 62) and PO2c Hitoshi Fukusawa (Pilot 27) were killed while PO3c Namitaro Matsushima (Pilot 30) was taken prisoner but later returned) after having been intercepted by a reported 50 Chinese aircraft.

By order of the staff, the Air Force on 29 August moved the 32nd PS with Gladiators under the command of the commander of the 3rd PG, Captain Wu Yu-Liu, to Nan Hsiung for defence against enemy air attacks.

At 09:50 on 30 August 1938, Nan Hsiung Command Post received a transmission that nine D1As had started from an airbase in Fujien to bomb Huizhou in the Guangdong Province. When it was confirmed that the D1As were crossing the Fujien/Jiangxi provincial border, Gladiators from the 3rd PG scrambled to intercept the enemy bombers. Once airborne the Gladiators divided into two formations. Captain Wu Yu-Liu led the first formation of five Gladiators while Zhu Jia-Xun, Squadron Leader of the 32nd Squadron, commanded the remaining four Gladiators. They were late, however, for at 10:30 the D1As had already completed their bomb run over Huizhou. It was estimated that over 30 bombs had been dropped creating extensive damage to the runway and the control building. When the Gladiators reached Huizhou, the D1As were already gone. Meanwhile military intelligence indicated that two more groups of enemy fighters and bombers were approaching Nan Hsiung. Wu thus led his Gladiators to report back to Nan Hsiung for CAP duties. While the Gladiators were racing for Nan Hsiung, the first group of 18 D1As arrived at Shaoguan at 10:50 to unload their bombs inflicting minor damage to the airbase facilities. The second group of eleven D1As escorted by an equal number of A5Ms reached Nan Hsiung at 10:40. The nine waiting Gladiators intercepted them. During the 45 minutes long combat Zhu Jia-Xun was credited with two victories while Squadron vice-commander Wei Dingleh and Wei Chienmu were credited with one victory each. Yang Yungjand and Tang Xingong each damaged an A5M. Japanese records shows that the Japanese Navy lost two pilots, Lieutenant Hideo Teshima (Class 58), Kaga's Division Officer, and PO2/c Seizaburo Sugino (Otsu 3). However, the 32nd Squadron suffered heavily with the loss of six Gladiators. Capitain Wu Yu-Liu was killed in his Gladiator. Vice-commander Ma Yujen landed with a damaged Gladiator and a severe leg wound, and he later died in hospital due to his wounds. Zhu Jia-Xun crash-landed his Gladiator and was wounded in the left eye. Squadron vice-commander Wei Dingleh was forced to bail out of Gladiator no. 3206, which was written off. Wei Chienmu and Tang Xingong were both shot down by the Japanese fighters and they both were forced to leave their Gladiators in parachute. Yang Yungjan made an emergency landing on his return inflicting minor damage to his Gladiator. This meant that the Chinese Air Force only had three operational Gladiators left after this combat.
The Japanese force seems to have consisted of six A5Ms led by Lieutenant Teshima, five carrier based bombers and 4 carrier based attack planes from Kaga and the returning Japanese pilots claimed 17 Gladiators (Dewoitines and Hawks were also reported) for the loss of two pilots (Teshima and Sugino).
Jiro Chono, who served as leader of the 2nd shotai of the escort claimed three victories in this combat and one probable despite his aircraft had suffered fifteen hits. Two more Gladiators were claimed by Osamu Kudo.

Zhu Jia-Xun ended the war with 5 biplane victories, three being claimed while flying Polikarpov I-15bis and two while flying Gloster Gladiator Mk.Is.

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1938
1	18/03/38		1	Type 93 (a)	Destroyed	I-15bis		Hsuchow area	8th PS
2	10/04/38		1	Type 97 (b)	Destroyed	I-15bis		Hsuchow area	8th PS
3	29/04/38	14:00-	1	G3M2 (c)	Destroyed	I-15bis		SE Wuchang	8th PS
	03/08/38		1	A5M	Damaged	Gladiator I		Hankou area	32nd PS
4	30/08/38		1	Enemy aircraft (d)	Destroyed	Gladiator I		Nan Hsiung	32nd PS
5	30/08/38		1	Enemy aircraft (d)	Destroyed	Gladiator I		Nan Hsiung	32nd PS

Biplane victories: 5 destroyed, 1 damaged.
TOTAL: 5 destroyed, 1 damaged.
(a) Type 93 twin-engine heavy bomber of the 6th Daitai (Group) shot down and crashing in flames. The pilot Captain Saburo Towata and the crew were all killed.
(b) Sergeant Major Risaburo Saito (NCO50) of 2nd Daitai shot down and killed.
(c) Claimed in combat with G3M2s of the 13th Kokutai and A5Ms of the 12th Kokutai of the Japanese Naval Air Force. Chinese pilots and Russian voluntary pilots claimed 21 Japanese aircraft, 11 fighters and 10 bombers, but it seems that only two G3M2s and two A5Ms were admitted. The Japanese claimed 40 Chinese aircraft but only twelve aircraft of the Chinese and Soviet volunteers were lost and five pilots killed.
(d) 32nd PS claimed four aircraft in this combat. Japanese Navy lost two pilots; Lieutenant Hideo Teshima, Kaga's Division Officer, and PO2/c Seizaburo Sugino.

Sources:
Chinese Air Force Gladiators in Action - D. Y. Louie, 1998 Small Air Forces Observer vol. 22 no. 4 (88) December 1998 kindly provided by Santiago Flores.
Japanese Army Air Force fighter units and their aces 1931-1945 - Ikuhiko Hata, Yasuho Izawa and Christopher Shores, 2002 Grub Street, London, ISBN 1-902304-89-6
Japanese Naval Aces and Fighter Units in World War II - Ikuhiko Hata and Yasuho Izawa, translated by Don Cyril Gorham, 1989 United States Naval Institute, Annapolis, ISBN 0-87021-315-6
Ki-27 'Nate' Aces – Nicholas Millman, 2013 Osprey Publishing, Oxford, ISBN 978-1-84908-662-2
Soviet Fighters in the sky of China, Part II - Anatolii Demin, 2000 Aviatsiia Kosmonavtika 10 (translated by George M. Mellinger)
Soviet Fighters in the sky of China, Part III - Anatolii Demin, 2000 Aviatsiia Kosmonavtika 11 (translated by George M. Mellinger)
Stars & Bars - Frank Olynyk, 1995 Grub Street, London, ISBN 1-898697-17-5
Additional information kindly provided by Raymond Cheung and Tom Chan, Andrei Demjanko and Mirek Wawrzyński.