Lieutenant Wang Yu-Kun served in the 23rd PS of the 4th PG.

As Japanese troop advanced on Wuhan, the temporary capital of the Chinese government, the 4th PG was made responsible for the air defence of the city and was based at Fencheng.
On 18 February 1938 the Japanese attacked the town with a reported 16 bombers, escorted by 26 fighters. In fact the actual composition of the Japanese force was 15 G3M bombers escorted by 11 A5M carrier fighters. The G3Ms were from the Kanoya Kokutai and led by Lieutenant Commander Sugahisa Tuneru. The escorts were from the 12th and 13th Kokutais and led by Lieutenant Takashi Kaneko of the 12th Kokutai.
According to Japanese accounts, there were low clouds over Wuhan, which caused a lot of confusion. Following warning from the air raid warning net, the Chinese interceptors began taking off at 12:45. First came eight I-15bis from the 23rd PS based at Hsiao-Kan led by Captain Lu Ji-Chun. Then came eleven I-15bis from the 22nd PS led by Captain Lee Kuei-Tan, commander of the 4th PG, which took off from Hankou Airfield at 13:00. Finally, ten I-16s of the 21st PS led by the commander Captain Teng Ming-Teh took off from Hankou Airfield at 13:10.
The first Chinese interceptors to encounter the Japanese were the I-15bis from the 22nd PS led by Lee’s flight, which included Lieutenant Cheng Hsiao-Yu in the no. 2 position, Lieutenant Chang Kuang-Ming as no. 3 and Lieutenant Pa Ching-Cheng as no. 4, were climbing steeply at about 1500 meters south west of the airfield three minutes after take-off. Japanese planes from the upper rear intercepted them from an altitude thought to be at 4000 meters. Other Chinese accounts indicate that six A5Ms attacked the first six aircraft in the Chinese formation and another 6 (sic) attacked the two flights of five bringing up the rear. It would appear that it was the 12th Kokutai A5Ms led by Lieutenant Kaneko that attacked Captain Lee and the first two flights of the 22nd PS. Other A5Ms, including those from the 13th Kokutai, attacked the two rear flights of the 22nd PS. Caught by surprise, the 22nd PS was hard hit and the Chinese planes were badly scattered. Badly shot up in the initial attack, Lee managed to regain control and headed back to Hankou Airfield. Witnesses on the ground saw him attempting to land his stricken I-15bis. Unfortunately, it would appear that Lee’s fuel tanks had been hit and were leaking because, while on final approach, the I-15bis suddenly burst into flames and crashed. Lee, the youngest Commanding Officer of the 4th PG at the time, was killed. Cheng and Pa were hit at the same time and spiralled down. Chang was attacked by three Japanese aircraft more than a dozen times. He damaged one of the enemy aircraft, and landed without injury to himself but counted over 210 bullet holes on his aircraft, including three rounds lodged in his parachute pack seat. Pa was killed when his aircraft crashed but Cheng spiralled down and landed safely. After landing he found his rudder cable severed by a Japanese bullet.
At the rear of the 22nd PS formation, things were just as desperate when they engaged the Japanese at 3000 meters south-west of Hankou. Lieutenant Wang Yi was shot down and killed. Captain Liu Chi-Han, 22nd PS leader, claimed to have shot down the A5M attacking him in a turning fight. However, Liu’s own engine was also hit in the fight and it exploded shortly afterwards, forcing Liu to bail out. While descending in his parachute, two A5Ms came in to strafe Liu. Liu recalled that the Japanese bullets zipped by "like hailstones". After dodging couple of passes, Liu allowed his body to go limp and "played dead". Thinking that the Chinese pilot had been killed, the Japanese broke away allowing Liu to land safely. Lieutenant Li Peng-Hsiang, also in the rear of the formation, came under attack by a 13th Kokutai A5M flown by shotai leader PO1c Mitsuga Mori. Lieutenant Wu Ting-Chun tried to intervene by attacking from above and behind Mori. However, Mori turned sharply away from the attack, causing Wu to collide with Li. Wu managed to bail out and survive but Li was killed. According to other sources Wu claimed to have downed a Japanese fighter, and then crashed into another one. On returning, Mori claimed to have downed two other I-15bis (his first 4 victories of a total of 9 – 4 in China). Feng Yu-Ho claimed two Japanese aircraft and Chang Ming-Sheng claimed a Japanese light bomber.
Arriving from Hsiao-Kan, the 23rd PS I-15bis led by Captain Lu Ji-Chun saw the surviving 22nd PS planes being chased all over the skies by the Japanese A5Ms. Joining the melee, the eight I-15bis of the 23rd PS took the heat off the 22nd PS, allowing the badly mauled survivors to escape. The Japanese A5Ms, having come off their success against the 22nd PS, were fighting well with their flights largely intact. The 23rd PS soon found themselves at a disadvantage. It would appear that the Chinese fighters were not able to effectively support each other in the fight. Once again, individual Chinese fighters found themselves under attack by flights of three A5Ms. Somewhere in the melee, Captain Lu was isolated, shot down and killed. Lieutenant Wang Yu-Kun, after claiming to have downed two A5Ms, came under attack by three others. Wang’s controls were shot away and the I-15bis went into a long glide towards fields north east of Wuhan. The Japanese planes continued to fire on Wang’s plane but, fortunately, the Chinese pilot was not hit. The I-15bis eventually crash-landed in a field, Wang was knocked unconscious but he survived with only a bruised right leg. Liu Chung-Wu and Hsin Sau-Chuan each claimed a victory. Hsin was so close to the Japanese aircraft he shot down that lubricants of the Japanese aircraft splashed on his windshield and totally obstructed his vision and he had to break off action.
Just as it appeared that the 23rd PS was going to suffer the fate of its sister squadron, the tables were turned with the arrival of ten I-16s from the 21st PS. Having climbed to 3500 meters north-west of the airfield, the 21st PS led by Captain Teng, saw the A5Ms dive from approximately 4000 meters altitude and attack the 22nd PS south west of Wuhan. Arriving on the scene with an advantage in altitude, the I-16s were able to surprise the Japanese, which were tangled in a dogfight with the 23rd PS. This time, it was the turn of individual Japanese fighters to be attacked by the Chinese in flights of three. Lieutenant Liu Chi-Sheng scored a solo kill and then joined Captain Teng and Lieutenant Yang Ku-Fan to attack another A5M which was engaged in a turning fight with Lieutenant Liu Chung-Wu of the 23rd PS. Together, the four Chinese fighters shot down this hapless A5M. Lieutenant Yang Ku-Fan then joined with Lieutenant Li Wen-Hsiang, Lieutenant Wang Teh-Lian and Lieutenant Han Sen to down another A5M. Finally, Lieutenant Huang Yuan-Po, Lieutenant Wang Teh-Lian and Lieutenant Kung Yeh-Ti combined to down a fourth A5M.
Soviet volunteers also took part in this combat and according to the recollections of the volunteer Aleksey Dushin, about 10 o’clock in the morning they took off on an alert and at an altitude of 4500 m found themselves under cumulus clouds. An arrow on the ground pointed out the direction from which the Japanese would appear. After a ten-minute flight along this course they turned and flew back, and straightaway they discovered about 1500-2000 m beneath them, three flights, each of nine Japanese bombers flying in a tight formation. Moments later Japanese fighters appeared flying above the clouds. They began to dive on the Soviet volunteers on a meeting course, with the initiative remaining with them. Three Japanese attacked Dushin, and consequently he shot at all three. A cone of bullets, in his words, found one aircraft, but it did not burn. Two A5Ms began to fire at him, but he was rescued by the manoeuvrability of the I-15bis. Dushin was able to escape from them by diving, but on the way out the third Japanese caught him. But an I-16 came to his rescue, which later turned out to have been flown by Aleksey Blagoveshchenskiy (or Ivan Puntus according to other sources). Dushin then chased after “his” Japanese and opened fire at a distance of 25 meters. But the guns suddenly ceased, out of ammunition. Nonetheless the A5M made an unnatural climb upward and vanished from the pilot’s field of vision. Several days later a Japanese fighter was found in this region, in Dushin’s opinion, the very same one.
Blagoveshchenskiy fought an air-combat with a leader of a Japanese group of fighters and he shot down the Japanese fighter. His own fighter was however damaged and he suffered from a damage control stick, hits on the armour plate and tears on his flight suit.
It seems that Georgii Konev claimed an enemy aircraft in this combat while flying an I-16 and Ivan Puntus claimed an A5M. Leytenant Dimitriy Kudymov (I-16) also claimed an A5M.
In this combat was the commander of the I-15bis squadron N. A. Smirnov killed together with a second volunteer. After the death of Smirnov the commander officially became A. S. Zingaev, though the “chief” of the group remained Blagoveshchenskiy himself. Totally the Soviet volunteers claimed five victories in this combat.
Four Japanese pilots were lost in this combat. They were Lieutenant Takashi Kaneko (Class no. 57), leader of the escorting fighters, PO1c Shigeo Miyamoto (Otsu 1), Sea1c Hiroji Hayakgawa (Pilot 29), all from the 12th Kokutai and PO1c Inao Hamada (Pilot 34) of the 13th Kokutai. In addition, one A5M from the 13th Kokutai was damaged and the pilot, NAP3c Airora Sao, badly injured by two bullets. For their part, Japanese pilots claimed a total of 15 I-15bis (including one probable), two I-16s and one SB. The Chinese pilots totally claimed at least twelve Japanese aircraft in this combat. Captain Lee Kuei-Tan, Captain Lu Ji-Chun, Lieutenant Pa Ching-Cheng, Lieutenant Wang Yi and Lieutenant Li Peng-Hsiang were killed during the battle.

In 1940 he served as Squadron Commander of the 23rd PS.

Wang Yu-Kun ended the war with 2 biplane victories, these being claimed while flying Polikarpov I-15bis.

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1938
1	18/02/38	12:45-	1	A5M (a)	Destroyed	I-15bis		SW Hankou	23rd PS
2	18/02/38	12:45-	1	A5M (a)	Destroyed	I-15bis		SW Hankou	23rd PS

Biplane victories: 2 destroyed.
TOTAL: 2 destroyed.
(a) Claimed in combat with A5Ms from 12th and 13th Kokutais, which lost four A5Ms with a fifth damaged while claiming 15 I-15bis (including one probable), two I-16s and one SB. The 4th PG claimed at least 11 A5Ms (and one damaged) and one light bomber while losing at least nine I-15bis (no I-16s) and getting one I-15bis damaged. The Soviet volunteers claimed 5 victories while losing two I-15bis.

Sources:
Chang Kuang-Ming, 1998 World News Weekly August 1998 kindly provided by Tom Chan
Polikarpov I-15, I-16 and I-153 Aces - Mikhail Maslov, 2010 Osprey Publishing, Oxford, ISBN 978-1-84603-981-2
Most information kindly provided by Raymond Cheung and Tom Chan.
Additional information kindly provided by Erich Wang.