Nomonhan Incident (May - September 1939)

Manchuria Map, 1939

Japan occupied Manchuria in 1931 and established the puppet state of Manchukuo. To the west, Manchukuo's border was the Mongolian People's Republic, the only communist state in the world at that time other than the Soviet Union and a Soviet allied.

In 1939, there were disputes about the border line between Mongolia and Manchukuo, with the Japanese claiming the border to be the Khalkhyn river (Khalkhyn Gol) and the Soviets arguing it to be 16 km east of the river, by the town of Nomonhan. These disputes rapidly escalated to what came to be known as the Nomonhan Incident in Japan and the Battle of Khalkhyn Gol in Soviet Russia.

Japanese Forces at Nomonhan (Pinterest)

On May 11th 1939, about 70-80 Mongolian cavalry men entered the disputed area to feed their horses. Manchuoko´s cavalry attacked and expelled the Mongolians back to their land, but Mongolians counterattacked on May 13th with greater numbers and the Manchuoko's men were forced to retreat. The Japanese deployed the 23th Division led by Lieutenant General Michitarō Komatsubara (under command of the Kwantung Army) and drove the Mongolians out. On May 28th, Mongolian and Soviet forces returned to the disputed area and defeated the reconnaissance regiment of the 23th division, causing the first major defeat for the Japanese.

Then both the Soviets and the Japanese began to bring reinforcements to the area. The Japanese added the Yasuoka Detachment, consisting on the 26th Infantry Regiment of the 7th Infantry Division led by Colonel Shinichiro Sumi, the 3rd Medium Tank Regiment of Colonel Kiyotake Yoshimaru and the 4th Light Tank Regiment under command of Colonel Tamada Yoshio to the already present 23th Division and the 8th Border Guards Regiment of the Manchukuo army. In total, the Japanese fielded up to 38,000 men, 73 tanks, 64 tankettes, 400 aircraft and about 250 artillery pieces.

Georgy Zhukov (Wikipedia)

On the other side, the Soviet forces comprised up to 73,000 men, more than 500 tanks and 450 armored cars, 900 aircraft and up to 600 artillery pieces, under command of Commanding officer of the Corps Georgy Zhukov, who was to become the most successful soviet commander through WWII.

The Japanese were not only outnumbered in strength, but also were equipped with less powerful tanks and artillery and did not have the means to maintain a proper line of supply. Between June and August, several battles were fought with only a few of them resulting in Japanese victories.

On August 20th, Zhukov launched a massive tank and infantry attack on Japanese positions, preceded by heavy artillery and aircraft bombing. Soviet armored units outflanked the Japanese and attacked them in the rear, isolating the 23th Infantry Division, which was almost completely destroyed by August 31st.

Japanese troops crossing the Khalkhyn Gol (Wikipedia).

Japan and the Soviet Union agreed to cease fire on September 15th, and Stalin invaded Poland two days later.

This battle had several consequences on the development of Japanese war strategies but also to the outcome of the war in general.

The humiliating Japanese defeat played an important role in the decision of expanding south of the Pacific instead of attacking Russia in 1941 (as Germany, Japan allied, wanted). The Japanese attacked Pearl Harbor instead, dragging the Americans into the war.

Japanese expansion to the south enabled Stalin to redeploy his Siberian troops to defend against German invasion, which turned out to have a major impact in turning the tide of the war.

The Nomorhan incident played a major role in the development of the war, despite being a quite unknown and forgotten battle.

Sources:

- Wikipedia
- The Pacific War Online Encyclopedia
- firedirectioncenter.blogspot.se