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Chang Kufeng / Zhang Gufeng Incident
Nuomenkan / Nomonhan Incident

From the political viewpoint, the Nomonhan Incident of 1939 represented a Soviet stratagem designed to hamper Japan's efforts at settling the China Incident. The Soviets instigated the border incident to accomplish certain of their diplomatic objectives, at the very time that a precarious situation was prevailing in Europe on the eve of World War II. In strategic terms, both the Japanese and the Soviets massed heavily in the Nomonhan area, where it was extremely difficult to carry out logistical operations. For some three months, the two sides fought modern-style battles involving air and ground forces, in actions which were a forerunner of the pattern evolved in the second World War.

The Kwantung Army, to uphold its command prestige, sought to resolve the Nomonhan Incident through unilateral measures involving direct action. As a consequence, the views of the Army High Command authorities in Tokyo, and those of Kwantung Army Headquarter in Hsinking, clashed head on. While matters were still deadlocked, the Kwantung Army proceeded to commit a handful of troops to cope with far superior Soviet forces. The Incident was eventually settled in the Soviet's favor, after thousands of casualties had been incurred, and the highest-ranking officers of the Kwantung Army had been removed.

The Imperial Japanese Army's takeover of Manchuria in 1931 brought Japanese and Soviet armed forces eyeball to eyeball along a 3,000-mile border. Numerous border skirmishes and disputes characterized the next several years as both sides reinforced their respective forces. In 1936 the Soviets signed a mutual assistance treaty with Outer Mongolia, and in January 1937 the Soviet High Command organized the 57th Special Rifle Corps consisting of the 36th Motorized Rifle Division, 6th Cavalry Brigade, 11th Tank Brigade, and 7th, Sth, and 9th Armored Car brigades. These units moved into Outer Mongolia in 1938.

In July 1938 and from May to August 1939, the Japanese army provoked two border conflicts against the Soviet Union, known as the Zhang Gufeng Incident [Chang Kufeng] and the Nuomenkan Incident [Nomonhan]. Geography, the combatants' compulsive secrecy, and the subsequent outbreak of World War II in September 1939 all combined to overshadow the most massive use of tanks theretofore recorded. The Soviets used over 1,000 tanks during the fighting and, under the command of General Georgi K. Zhukov, evidenced skill and sophistication at mechanized warfare. The Imperial Japanese Army (IJA), essentially an infantry force, fared poorly, and fell victim to a Soviet double envelopment.

Japan's occupation and annexation of neighboring Manchuria in 1931 left no doubt of Tokyo's long-range objectives in Northeast Asia. A program of subversion among the Mongolians and of agitation in support of pan-Mongolism was followed by minor clashes along the Mongolian-Manchurian border in 1934 that reached major intensity in 1935. After serious clashes with the Japanese along the eastern Mongolian border in early 1935, a conference of Mongolian and Japanese representatives was convened in June at the Chinese border town of Manzhouli to settle border demarcation and other matters. After six months without reaching agreement, the effort was abandoned.

On March 1, 1936, Josef Stalin publicly and unequivocally stated that "If Japan should venture to attack the Mongolian People's Republic and encroach upon its independence, we will have to help the Mongolian People's Republic... just as we helped in 1921...." Two weeks later, a Protocol Treaty of Friendship and Mutual Assistance reiterated the main provisions of the 1934 agreement. Apparently the Soviets at the time were less concerned about Chinese sensibilities than they had been earlier. The protocol was to run for ten years; it provided for joint consultation and protective action in the event of threat to either party by a third power, for military assistance in the case of a third-power attack, and for the stationing of troops in each other's territory as necessary.

Some Soviet troops had remained in Mongolia after the suppression of the revolts; when Japan invaded northern China and occupied Inner Mongolia, this treaty provided a basis for increasing Soviet strength to a reinforced corps, the Fifty-seventh Independent Rifle Corps.

In 1937 the Japanese invaded northern China, which enabled Japanese forces to occupy the Inner Mongolian provinces of Qahar and Suiyuan along Mongolia's southern border. This widened the zone of contact between Mongolian and Japanese forces and increased Mongolian security problems. Incidents continued along the Mongolian borders with Manchuria and Inner Mongolia. In July 1938, the Japanese Guandong (Kwantung in Wade-Giles romanization) Army (the Japanese army in Manchuria, 1931-45) mounted a major, yet unsuccessful, attack against Soviet positions in an ambiguously demarcated area along the Manchurian-Siberian border near Vladivostok. Frustrated along the Siberian border, Japan turned the following year to the more vulnerable Mongolian border, where it thought that subversion against the Mongolians would pave the way.

Mongolia's easternmost portion is a salient jutting deep into Manchuria. A branch railroad runs from Changchun on the Shenyang-Harbin railroad to within a few kilometers of the border; on the other side of the frontier, the Halhin Gol runs parallel to the border on the Mongolian side for about 70 kilometers. This area had been the scene of serious clashes in early 1935.

An especially bloody affray at Changkufeng/Lake Khasan in 1938 resulted in over 2,500 casualties on both sides. It also seemed to stiffen Soviet resolve because the following year, Joseph Stalin, speaking before the Eighteenth Soviet Party Congress in March 1939, warned that any acts of aggression against the inviolable Soviet frontiers would be met by twice the force of any invader. Two months later, a handful of Soviet allied Outer Mongolian cavalry troops wandered into a disputed border area between the Halha River (Soviet name, Khalkhin Gol) and the tiny village of Nomonhan. The Japanese claimed that the boundary followed the river, but the Soviets maintained that it passed just east of the village of Nomonhan.

To facilitate military deployment into this vulnerable area, the Soviet Union built a wide-gauge railroad, completed in 1939, connecting the Chinese-Eastern railroad to the Mongolian town of Choybalsan. The frequency of border clashes increased until they occurred almost daily in this area during 1938 and early 1939. In early May 1939, Soviet foreign minister Vyacheslav M. Molotov issued another stern warning to Japan: "I give warning that the borders of the Mongolian People's Republic will be defended by the USSR as vigorously as we shall defend our own borders."

On May 11, 1939, the Japanese army occupied portions of Mongolia between the border and the Halhin Gol. A combined Mongolian-Soviet force quickly moved against the invaders. By the end of May, the joint force had seized a bridgehead on the Halhin Gol's eastern bank. To counter this move, the Japanese by early July concentrated a corps of 38,000 troops and attacked the northern flank of the Mongolian-Soviet bridgehead. The Japanese drove the allies back across the Halhin Gol, crossed it themselves, and established their own bridgehead on the western bank. On July 5, 1939, Soviet armor counterattacked and eliminated the Japanese bridgehead, after which both sides began a major force buildup.

During July 1939, the Mongolian-Soviet forces were reorganized. The Trans-Baykal Military District was set up as a front headquarters, with the First Army Group under General Georgi Zhukov as the striking force. Soviet forces were concentrated in eastern Mongolia, and the Mongolian army mobilized to its full strength of 80,000 in eight cavalry divisions; the 515 aircraft of the combined force were used mostly in screening the southern borders.

Zhukov's First Army Group included Mongolia's Sixth and Eighth Mongolian cavalry divisions, both of which were employed as flank protection for the army group along the 70-kilometer front on the Halhin Gol. Throughout early August 1939, probing attacks and occasional battalion-sized assaults by the Soviets characterized the activity on the battleground. Soviet artillery gained superiority and daily pounded Japanese positions. At the same time, General Zhukov built up his forces in preparation for a great Soviet offensive. The Soviets completed these preparations in complete secrecy, concealing the movement and disposition of their forces.

The Japanese decision to attack must have been based on faulty intelligence or on extreme overconfidence [the twin defects which plagued the Japanese military in the years prior to 1945], because the Japanese were weaker in infantry battalions by 30 percent, in tanks by 60 percent, and in aircraft by 25 percent. Further, Soviet intelligence was superior to the Japanese, because the Soviets had detected the Japanese buildup for the attack and had evidently correctly estimated its timing.

During July and early August, the Japanese forces, setting August 20, 1939, as the target date, prepared to cross the river and to destroy the opposing forces. At dawn August 20, 1939, the commander of the Mongolian-Soviet troops preempted the Japanese attack: 150 bombers struck Japanese positions, rear areas, and lines of communication. A ground attack by the southern and the northern wings of the First Army Group penetrated the Japanese flank with armor and infantry, and then they turned inward in a classic double envelopment as Mongolian cavalry protected the outer flanks.

The Japanese defended tenaciously, but by August 23 the Soviets had encircled the Japanese forces along the Halhin Gol. For five days, the Mongolian-Soviet forces beat back fierce attacks by Japanese relief forces as well as attempts by the surrounded units to break out. Japanese relief attempts slackened, and pockets of resistance were cleared out. On August 31, 1939, the Mongolian-Soviet forces advanced to the frontier.

Faced with the drastically new situation in Europe, the antagonists at Nomonhan/Khalkhin Gol suspended major military operations. The tempo of diplomatic negotiations already underway between Japan and the Soviet Union quickened and the fighting diminished in early September 1939. On September 15, 1939, [i.e. two weeks after the commencement of World War II] Stalin concluded a durable ceasefire with Japan, to take effect the following day. The day after that, September 17, Stalin belatedly joined Germany in the joint invasion of Poland.

Soviet casualties came to nearly 10,000, and the Mongolians lost 1,130. Japanese losses in the four months of fighting were extremely heavy: over 17,000, including 8,440 killed and 8,766 wounded. Soviet casualties were given as 9,284 killed and wounded. Total Japanese losses may have been far greater, with more than 18,000 killed and 25,000 wounded (some total estimates were as high as 80,000). More than 170 guns and 200 aircraft were lost. After the defeat, Japan turned its military thrust southward. On June 9, 1940, an agreement fixing the Manchukuo-Mongolian border was signed in Moscow.

After occupying South Manchuria of China, Japan forced the USSR to retreat from North Manchuria. To avoid conflict, after obtaining some benefits, the USSR retreated to Siberia and China's Outer Mongolia. On 13 April 1941 Japan realized one of its major diplomatic objectives with the conclusion of the Japanese-Soviet "Non-Aggression Pact." The Soviet-Japanese Neutrality Pact, which included a Soviet pledge to recognize the territorial integrity of Manchukuo and a similar Japanese pledge with respect to Mongolia.

However, the outbreak of the Soviet-German war only two months later created an entirely new situation. After Germany's invasion of the Soviet Union in June 1941, the Konoye Cabinet resigned on 16 July, reassembling two days later under the same Premier but with Matsuoka, the architect of the Axis Pact, replaced as Foreign Minister by Admiral Teijiro Toyoda. The new cabinet was geared to rehabilitate relations with the United States, a course that conservative Navy elements had stoutly advocated. The Japan-USSR Neutrality Treaty of 1941 was an invitation to divide China's Manchuria and Mongolia.

The entry of the United States into World War II in December 1941 fully committed the Soviet Union and Japan to other flanks of their respective domains; thus, their Mongolian flanks remained relatively quiet until the final weeks of World War II.

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Page last modified: 21-02-2022 13:35:32 ZULU