The Battles of Khalkhin Gol (Russian: Бои на Халхин-Голе, romanized: Boy na Khalkhin-Gole; Mongolian: Халхын голын байлдаан, romanized: Khalkhyn golyn baildaan), known in Japan as the Nomonhan Incident (Japanese: ノモンハン事件, Hepburn: Nomonhan jiken) after Nomonhan Burd Obo, were the decisive engagements of the undeclared Soviet–Japanese border conflicts which involved the Soviet Union, Mongolia, Japan, and Manchukuo in 1939. The conflict is named after the river Khalkhin Gol, which passes through the battlefield. The Soviet offensive, led by general Georgy Zhukov, utilized airplanes, tanks, and infantry in a simultaneous three-pronged offensive, the first of its kind in modern warfare. Similar tactics were later used during Operation Uranus at the Battle of Stalingrad.
The Soviet–Japanese Neutrality Pact was later signed in April 1941. The decisive Soviet victory altered the eventual course of World War II by dissuading the Empire of Japan from any further confrontation with the Soviet Union under its Hokushin-ron (strike north) doctrine. During World War II, Japan favored the Nanshin-ron (strike south) strategy, attacking Southeast Asia rather than Siberia, eventually leading to the Japanese attack on Pearl Harbor and American entry into World War II in December 1941.
Background
Mongolia as a buffer
After the Japanese occupation of Manchuria in 1931, Japan turned its military interests to Soviet territories that bordered those areas. Meanwhile, the Soviet Union and the People's Republic of Mongolia signed a Mutual Assistance Pact in March 1936, allowing the former to send troops to Mongolia. In the same year, Japan signed the Anti-Comintern Pact in response. Following Japan's full invasion of China in July 1937, the Soviet Union sent the 57th Special Corps led by Ivan Konev to Mongolia. On 13 June, Genrikh Lyushkov, a Soviet NKVD major general who knew Stalin personally, defected to Japan for fear of the Great Purge. He took with him a large number of secret documents that allegedly revealed the dire situation of the Soviet army in the Far East. The first major Soviet-Japanese border incident, the Battle of Lake Khasan, occurred in 1938 in Primorye. Clashes between Japanese and Soviet forces occurred frequently along the border of Manchuria.
In 1939, Manchuria was a puppet state of Japan known as Manchukuo, and Mongolia was a communist state allied with the Soviet Union, known as the Mongolian People's Republic. The Japanese maintained that the border between Manchukuo and Mongolia was the Khalkhin Gol (English "Khalkha River"), which flows into Lake Buir. In contrast, the Mongolians and their Soviet allies maintained that the border ran 16 kilometres (10 mi) east of the river, just east of Nomonhan.
The principal occupying army of Manchukuo was the Kwantung Army of Japan, which had instructions from the Japanese Cabinet to strengthen and fortify Manchukuo's borders with Mongolia and the Soviet Union. However, the Kwantung Army, which had long been stationed in Manchuria far from the Japanese Home Islands, had become largely autonomous and tended to act without approval from, or even against the direction of, the Japanese government.
Battles
May: Skirmishes
The battles began on 11 May 1939. A Mongolian cavalry unit of 70 to 90 men had entered the disputed area in search of grazing for their horses. On that day, Manchu cavalry attacked the Mongolians and drove them back across the river Khalkhin Gol. On 13 May, the Mongolian force returned in greater numbers and the Manchukoans failed to dislodge them.
On 14 May, Lt. Col. Yaozo Azuma led the reconnaissance regiment of the 23rd Infantry Division, supported by the 64th Infantry Regiment of the same division, under Colonel Takemitsu Yamagata, into the territory, and the Mongolians withdrew. Soviet and Mongolian troops returned to the disputed region however, and Azuma's force again moved to evict them, but the Soviet-Mongolian forces surrounded Azuma's force on 28 May and destroyed it. The Azuma force suffered eight officers and 97 men killed, and one officer and 33 men wounded, for 63% total casualties.
June: Escalation
Both sides increased their forces in the area. On 5 June, Zhukov, the new corps commander, arrived, and brought more motorized and armored forces (I Army Group) to the combat zone. Accompanying Zhukov was Comcor Yakov Smushkevich with his aviation unit. Zhamyangiyn Lhagvasuren, Corps Commissar of the Mongolian People's Revolutionary Army, was appointed Zhukov's deputy.
On 27 June, the Japanese Army Air Force's 2nd Air Brigade struck the Soviet airbase at Tamsak-Bulak in Mongolia. The Japanese won this engagement, but the strike had been ordered by the Kwantung Army without obtaining permission from Imperial Japanese Army (IJA) headquarters in Tokyo. In an effort to prevent the incident from escalating, Tokyo promptly ordered the JAAF not to conduct any more air-strikes against Soviet airbases.
Throughout June, there were reports of Soviet and Mongolian activity on both sides of the river near Nomonhan, and small-scale attacks upon isolated Manchukoan units. At the end of the month, the commander of the 23rd Japanese Infantry Division, Lt. Gen. Michitarō Komatsubara, received permission to "expel the invaders".
July: Japanese assault
The Japanese planned a two-pronged assault. The first attack would be made by three regiments plus part of a fourth: the 71st and 72nd Infantry Regiment (23rd Division), a battalion of the 64th Infantry Regiment and the 26th Infantry Regiment under Colonel Shinichiro Sumi (7th Infantry Division). This force would advance across the Khalkhin Gol, destroy Soviet forces on Baintsagan Hill on the west bank, then make a left turn and advance south to the Kawatama Bridge. The second prong of the attack would be the task of the IJA 1st Tank Corps (1st TC) (Yasuoka Detachment), consisting of the 3rd and 4th Tank Regiments, plus a part of the 64th Infantry Regiment, a battalion from the 28th Infantry Regiment, detached from the 7th Infantry, 24th Engineer Regiment, and a battalion from the 13th Field-Artillery Regiment, all under the overall command of Lieutenant General Yasuoka Masaomi. This force would attack Soviet troops on the east bank of the Khalkhin Gol and north of the Holsten River. The two Japanese thrusts were to join on the wings. The order of battle was thus:
The northern task force succeeded in crossing the Khalkhin Gol, driving the Soviets from Baintsagan Hill, and advancing south along the west bank. However, Zhukov, perceiving the threat, launched a counterattack with 450 tanks and armored cars. The tanks consisted primarily of BT tanks with a handful of T-26s, while the armored cars were BA-10s and BA-3/6s, which were similar in armor (6–15 mm (0.24–0.59 in)) and armament (main: 45 mm (2 in) gun 20K mod, secondary: two 7.62 mm (0.30 in) machine guns) to the Soviet light tanks.
The Soviet armored force, despite being unsupported by infantry, attacked the Japanese on three sides and nearly encircled them. The Japanese force, further handicapped by having only one pontoon bridge across the river for supplies, was forced to withdraw, recrossing the river on 5 July.
Meanwhile, the 1st Tank Corps of the Yasuoka Detachment (the southern task force) attacked on the night of 2 July, moving in the darkness to avoid the Soviet artillery on the high ground of the river's west bank. A pitched battle ensued in which the Yasuoka Detachment lost over half its armor, but still could not break through the Soviet forces on the east bank and reach the Kawatama Bridge. After a Soviet counterattack on 9 July threw the battered, depleted Yasuoka Detachment back, it was dissolved and Yasuoka was relieved.
The two armies continued to spar with each other over the next two weeks along a four-kilometre (2.5 mi) front running along the east bank of the Khalkhin Gol to its junction with the Holsten River. Zhukov, whose army was 748 km (465 mi) away from its base of supply, assembled a fleet of 2,600 trucks to supply his troops, while the Japanese suffered severe supply problems due to a lack of similar motor transport. In early July the Japanese had only 600 trucks, rising to 1,000 by the end of the month, of which only 75% were operable. By 20 August the Japanese managed to accumulate 2,000 trucks delivering 1,500 tons of supply daily, but even this fell below the Red Army's capabilities.
On 23 July, the Japanese launched another large-scale assault, sending the 64th and 72nd Infantry Regiments against Soviet forces defending the Kawatama Bridge. Over a period of two days, Japanese artillery supported the attack with a massive barrage that consumed more than half of their ammunition stores. The attack made some progress but failed to break through Soviet lines and reach the bridge. The Japanese disengaged from the attack on 25 July due to mounting casualties and depleted artillery stores. By this point they had suffered over 5,000 casualties between late May and 25 July, with Soviet losses being much higher but more easily replaced. The battle drifted into a stalemate.
August: Soviet counterattack
With war apparently imminent in Europe, and to avoid fighting a two-front war, Zhukov planned a major offensive on 20 August 1939 to clear the Japanese from the Khalkhin Gol region and to end the fighting. Zhukov, using a fleet of at least 4,000 trucks, and transporting supplies from the nearest base in Chita 600 km (370 mi) away, assembled a powerful armored force of three tank brigades (the 4th, 6th, and 11th) and two mechanized brigades (the 7th and 8th, which were armored car units with attached infantry support). This force was allocated to the Soviet left and right wings. The entire Soviet force consisted of three rifle divisions, two tank divisions plus two more tank brigades (in all, around 498 BT-5 and BT-7 tanks), two motorized infantry divisions, and over 550 fighters and bombers. The Mongolians committed two cavalry divisions.
In comparison, at the point of contact, the Kwantung Army had only the 23rd Infantry Division, which, with various attached forces, was equivalent to two light infantry divisions. Its headquarters had been at Hailar, over 150 km (93 mi) from the fighting. Japanese intelligence, despite demonstrating an ability to track the build-up of Zhukov's force, failed to precipitate an appropriate response from below. Thus, when the Soviets finally did launch their offensive, Komatsubara was caught off guard.
To test the Japanese defenses prior to their main assault on 20 August, the Soviets launched three aggressive probing assaults, one on 3 August and the others on 7-8 August. All three were disastrously thrown back, with around 1,000 combined dead and several tanks knocked out on the Soviet side compared to just 85 Japanese casualties. The Japanese counterattacked and routed elements of the Mongolian 8th Cavalry Division, seizing a hilly sector of the battlefront.
Despite the fact that no more major fighting would take place until 20 August, Japanese casualties continued to mount at a rate of 40 wounded per day. Kwantung Army staff officers were becoming increasingly worried over the disorganized state of the 6th Army headquarters and supply elements. The growing casualty count meant that the green 23rd Division would have to take, train and assimilate new replacements "on the job". By contrast, Tokyo's oft-stated desire that it would not escalate the fighting at Khalkhin Gol proved immensely relieving to the Soviets, freed to hand-pick select units from across the military to be concentrated for a local offensive without fear of Japanese retaliation elsewhere.
Zhukov decided it was time to break the stalemate. At 05:45 on 20 August 1939, Soviet artillery and 557 aircraft attacked Japanese positions, the first fighter-bomber offensive in Soviet Air Force history. Approximately 50,000 Soviet and Mongolian soldiers of the 57th Special Corps attacked the east bank of the Khalkhin Gol. Three infantry divisions and a tank brigade crossed the river, supported by massed artillery and by the Soviet Air Force.
Once the Japanese were pinned down by the attack of Soviet center units, Soviet armored units swept around the flanks and attacked the Japanese in the rear, achieving a classic double envelopment. When the Soviet wings linked up by Nomonhan on 25 August, they trapped the Japanese 23rd Infantry Division. On 26 August, a Japanese counterattack to relieve the 23rd Division failed. On 27 August, the 23rd Division attempted to break out of the encirclement but failed. When the surrounded forces refused to surrender, they were again hit with artillery and air attacks. By 31 August, Japanese forces on the Mongolian side of the border were destroyed, leaving remnants of the 23rd Division on the Manchurian side. The Soviets had achieved their objective.
The Soviet Union and Japan agreed to a cease-fire on 15 September; it took effect the following day at 1:10 pm.