The Defense of the Salween River was the failed Japanese attempt to invade and cross the Salween River into Baoshan, Yunnan followed by the Chinese's failed counterattack to regain Tengchong and Longling.
Background
Britain also refused to build a railway from Burma to Yunnan province in China in 1938 which would ship war material. Foreign war supplies destined for China were stuck in Rangoon in 1939–1940, since Britain refused to allow fighter aircraft and trainers that China bought from foreign companies enter China via British Burma since Britain wanted to retain good relations with Japan.
The western Yunnan Longling and Tengchong Superintendent was warlord Long Yun's son Long Shengwu.
On 4 May, Longling was occupied by Japan. Yunnan warlord Long Yun's son Long Shengwu, the Tenglong supervisor, had three battalions consisting of 1,000 warlord soldiers in Tengchong, they abandoned the city on 6 May 1942 and Tengyue county magistrate Qiu Tianpei abandoned the city on 8 May 1942 leaving remaining troops leaderless and causing them to withdraw north, leaving no troops in the city and leaving the gates of the city walls wide open, days before the Japanese arrived. On 10 May 1942 the Japanese arrived at Tengchong city which had no troops manning the walls and the gate was open. On 15 May, Chiang Kai-shek sent three regiments of his own central army's Second Reserve Division north of Tengchong at Jiatou, after crossing the Salween River and they started enclosing the area around Tengchong to siege the Japanese. In Jiatou, they set up a training school for military cadres which enlisted refugees from Tengchong to train them for war, including political officer Shao Ying-jen who was 18.
Battle
Bioweapons attack Imperial Japanese Army Air Service dropped bubonic plague and cholera bombs on Baoshan on 4 May. An American pilot also witnessed disease caused by Japanese bioweapons in west Yunnan.
AVG accounts of air operations Japanese fighters and bombers engaged in aerial combat over Baoshan with the AVG, with AVG claiming 8 Japanese fighters killed and Japanese admitting to losing 3 Ki-27 Type 97 fighters and 2 Ki-30 Type 97 light bombers. The Japanese gathered abandoned British and Chinese trucks for logistics. Wanding and Kutkai (35 miles from Lashio to the north) were the site of delaying battles fought by Chinese to slow down the Japanese as they readied positions east of the Salween River, where they demolished the Huitong bridge and retreated to by 5 May. The Japanese general Sakaguchi ordered Japanese troops to cross the Salween to conquer the east bank of the river, refusing to stop at the Salween and the AVG believed he intended to continue on to Kunming. The AVG sent a telegram to Chongqing asking for permission to attack the Japanese column by air to stop them from crossing the Salween ("Request authority to attack targets in between Salween and Lungling City."), and were given permission by the government in Chongqing to attack all boats and trucks between Longling and the Salween ("The generalissimo instructs you send all available AVG attack trucks, boats, etc., between Salween and Lungling City.").
The Boston Globe said ""On one side of the river stretched Japanese tanks, armored cars and lorries, packed close together and almost touching. On the other was a long column of stationary Chinese trucks,"
Japanese truck convoys were attacked by 6 Chinese army air force Tupolev SB-3 bombers on 6 May, but the bombers had to return to Kunming after a single mission since they were too broken down to continue. AVG pilots "Tex" Hill, Tom Jones, Frank Lawlor and Ed Rector were sent to fly P-40E Warhawks to dive bomb the Japanese trucks and bomb the Burma road itself to create an obstacle for the trucks. To carry Russian made 570-pound high-explosive bombs, the P-40Es were fitted with custom made centreline racks made by Chuck Baisden and Roy Hoffman, so they each carried a single 570-pound demolition bomb under the body of the bomber in addition to multiple 35-pound fragmentation bombs under each wing of the bomber. They were escorted by 4 Hawk 81s from the 3rd Squadron led by Arvid Olsen. They attacked on 7 May, flying from Kunming to Yunnanyi and then to the Salween where they say the Japanese 56th division's soldiers and trucks below. A pontoon bridge under construction by Japanese engineers was spotted by Hill from his bomber. Hill blocked the Burma road with rocks by bombing the gorge to make rocks fall onto the road and the other bombers followed him to block the road. A Japanese column was then targeted with fragmentation bombs by Hill and the three other bombers. The bombers then used their machine guns to strafe the Japanese until they ran out of bullets and then left and let the fighter planes continue strafing the Japanese since they no longer needed to guard the bombers. Chinese troops on the east bank of the Salween watched. On 8 May, 8 Hawk 81 fighter escorts led by R. T Smith again led another group of P-40E bombers led by Tom Jones to attack the Japanese column, with the bombers destroying 50 Japanese trucks. There were no attacks on 9 May due to weather, but the Chinese forces started ground attacks against the Japanese across the Salween River. The Japanese at Longling were attacked when the Salween River was crossed north of the former destroyed Huitong bridge by the Chinese 71st Army's 87th and 36th divisions as the Japanese were "off balance". The Japanese were attempting to construct their pontoon bridge with their artillery and tanks waiting. The Chinese air force under General Peter Mow also participated in the battle. The Japanese survivors from the strafings and bombings after AVG's second raid were attacked by Chinese on the ground.
200 Japanese casualties were estimated in the 50 trucks hit on the 8 May raid by Lew Bishop. American journalist and war historian Daniel Ford said that the Japanese advanced was finally halted by the Chinese ground troops action on Saturday, 9 May rather than by the air campaign waged by AVG. The Japanese progress was halted by the Chinese 71st Army's two divisions counter strikes across the river.
The Japanese supply trucks were forced to flee back to the Burmese border since the Sakaguchi Detachment's logistical line was under threat by the Chinese 36th division attack across the Salween river on 9 May. The Chinese landed on the west bank of the Salween towards the north of where the Japanese attempted to build their pontoon.
The Japanese column of vehicles stretched from the Salween all the way to Longling for miles, flanked on both sides with sheer bluffs and a rock wall, so the AVG and Chinese air wing were able to strafe and bomb them for four days with nowhere for the trapped Japanese to hide after the AVG blocked their escape routes to their front and rear by causing landslides by bombing the rock wall. At the road south of Longling Frank Schiel let a group of fighters to attack Japanese light tanks. A fuel carrying column of Japanese trucks was wiped out.
"Tex" Hill talked about the first raid on 7 May: "The monsoon season had already set in and we encountered some mighty rough weather before finally breaking out on the target side of the weather. We installed jury-rigged bomb racks to accommodate a new 570-lb. Russian high-explosive bomb on the bellies of our new P-40Es and fragmentation bombs mounted on the wing racks. Hill talked about how they blocked the road with rocks: "The bombs we dropped impacted on the top of the Salween gorge, completely trapping some of the many pieces of armor and equipment, as well as personnel, at the bottom of the gorge. We knocked off some of the road there, and it blocked them, and then we were able to strafe them."
Jim Howard say about the 8 May raid: "We glided down and released our bombs in string along portions of the Jap side of the road. My bombs landed squarely along about 200 yds. of road with Jap trucks bumper to bumper to bumper." and "black smoke and flame showed the results" Tom Jones talked about destroying Japanese trucks near the river that he said carried pontoon bridge pieces, and the Japanese refused to set them up during day time and would only start working at "night or when opposition from Chin[ese] soldiers across river should let up." He said the "destruction of these trucks, I believe, will hold up the Jap's plans for some time." and that the Japanese were in "general confusion," "[returning] fire with small arms after second pass by our planes." C. H. Laughlin said "dispersed trucks hid in brush on mountainside." and "dropped 2 bombs and observed large petrol fire" while Japanese "troops scrambling down side of hill away from trucks: dropped two more bombs and razed convoy with machine gun fire." He then strafed "small units of cars and trucks." twice more,
Japanese on the western slopes of the gorge were also bombed and strafed by Chinese pilots in 12 Hawk III fighters and Soviet manufactured bomber planes.
Japanese trucks further behind Longling were then bombed and strafed by 6 P-40Es and 6 Hawk 81s under R. T. Smith the day after that on 10 May. Smith said "It seems the Chinese are driving the Japs back down the road now, Hope it continues that direction.” The Japanese lost the battle to cross the Salween, despite the AVG in the air and Chinese ground forces on the east bank of the Salween having zero coordination with each other and they were attacking the Japanese completely independently, not communicating or sharing plans.
The pilots "threw everything we had against the Salween gorge and the Burma Road." The Washington Post mentioned the Chinese ground assaults across the Sawleen: "Chinese reinforcements were flung across the stream, and in a bitter struggle the main Japanese forces were thrust back . . . and the remnants . . were wiped out."
The Japanese completely stopped their attempts to advance beyond the Salween on 11 May. Japanese trucks then started retreating towards Burma. On 12 May the AVG reported that a large Japanese columns of 75-100 trucks was fleeing south, the leading truck of the column was south of Wanting while the last truck of the column was just at the entrance of the city at the other end, the entire column spanned Wanting city and was strafed and bombed by the AVG.
AVG Kittyhawks led by Adam and Eves were ordered on 22 May to bomb the remnants of the Sakaguchi detachment still clinging to the Salween's west bank.
Newspaper account of ground operations
Up to 15 May near Hungmushu in west Yunnan, Chinese attacks destroyed half of a Japanese column who were forced to flee back to the Burma Road. Chinese continued fighting in northeast Burma, along the Salween River and south of Longling..
On the Sunday before 18 May, Chinese attacks drove back a Japanese column from Longlong going northeast towards the Salween River and the Japanese column lost half its men. Chinese forces also fought Japanese to the south and southeast of Monghai and Monglen.
On 17 May, 27 miles west of Baoshan, a Japanese column was attacked and forced to flee back to Tengchong by a Chinese column that went across the Salween River. On the banks of the Salween to the east of Longling, Japanese and Chinese engaged in an artillery duel firing at each other across the river. The American Volunteer Group on 16 May bombed Japanese trains from Indo-China to Yunnan while Chinese planes bombed Japanese southwest of Longling at Mangshih during heavy rain.
On 18 May a Japanese column heading towards the Salween River were attacked by the Chinese at Kengtung and Longling. At the southeast of Kengtung Chinese drove the Japanese back twice.