In August 1939, just weeks before Hitler invaded Poland, the Soviet Union and Japan fought the largest tank battle the world had ever seen.

Under the then unknown General Georgy Zhukov, the Soviets won a crushing victory at the batte of Khalkhin-Gol (known in Japan as the Nomonhan Incident).

Defeat persuaded the Japanese to expand into the Pacific, where they saw the United States as a weaker opponent than the Soviet Union. If the Japanese had not lost at Khalkhin Gol, they may never have attacked Pearl Harbor.

The Japanese decision to expand southwards also meant that the Soviet Eastern flank was secured for the duration of the war. Instead of having to fight on two fronts, the Soviets could mass their troops – under the newly promoted General Zhukov – against the threat of Nazi Germany in the West.

In terms of its strategic impact, the battle of Khalkhin Gol was one of the most decisive battles of the Second World War, but no-one has ever heard of it. Why?

Rising Tensions

Manchuria MapIt was perhaps not all that surprising that the Soviet Union and Japan, two expansionist powers who just happened to be close neighbours, butted heads in the Mongolian borderlands.

Tensions between the two had been high for decades, and had erupted into open conflict on a number of occasions. Japan had clearly had an edge over Russia during the early part of the 20th century – it had decisively defeated Tsarist Russia in the Russo-Japanese war of 1905 (a conflict most memorable, perhaps, for the Russian Navy’s folly of sailing its entire Baltic fleet around the globe only to be promptly sunk by the Japanese Navy within days of its arrival), and had occupied Vladivostock for several years during the Russian civil war.

But, by the 1930s, the Soviet Union under Stalin was a resurgent power, and had become a major regional rival to the Japanese. The Japanese High Command were particularly concerned about the threat Soviet submarines posed to Japanese shipping, and the ease with which Soviet bombers, operating out of Vladivostok, would be able to reach Tokyo.


Mongolian cavalry at Khalkhin GolBy the late 1930s, both Mongolia and bordering Manchuria (Manchukuo) were Soviet and Japanese puppet states. The border between the two was hotly disputed.

Japanese backed Manchuria claimed that the border ran along the Khalkhin-Gol river, whereas Mongolia argued that the border actually ran just east of Nomonhan village, some 10 miles east of the river.

Although the two countries had previously fought some minor skirmishes (most notably at Changkufeng/Lake Khasan in 1938, a battle which resulted in more than 2,500 casualties on both sides), the battle of Khalkin Gol was sparked when, on 11 May 1938, a small Mongolian cavalry united entered the disputed area in search of grazing for their horses. They were quickly given a bloody nose and expelled by a larger Manchurian unit but, within days, the Mongolians returned with greater support and forced the Manchurian forces to retreat.

The conflict gradually escalated until Soviet and Japanese forces were drawn into direct conflict. On 28 May Soviet forces surrounded and destroyed a Japanese reconnaisance unit. The Japanese unit, led by Lt Colonel Yaozo Azuma suffered 63% casualties in total, losing 8 officers and 97 men, plus suffering 34 wounded.

A month of relative quiet followed this battle. But, instead of using the time to consider a peace deal, both sides redoubled their efforts to build up their forces in the region.

Daring Japanese Air Raid

japan air raid khalkhin golThe quiet was shattered on 27 June by a daring Japanese air-raid on the Soviet air base at Tamsak-Bulak in Mongolia. The unprepared Soviets lost many planes on the ground although, once they got airborne they gave a good account of themselves. Their skill, however, could not prevent the Japanese pilots returning gloriously home, having destroyed twice as many Soviet planes as they had lost themselves.

However, their glory was short-lived. The Imperial Japanese Army Headquarters, based in Tokyo, had not been told of the attack in advance, and was not amused at the local commander’s initiative. When news of the raid reached Tokyo, furious Generals immediately ordered that no further air strikes would be launched – a decision for which Japanese foot-soldiers later paid a high price.

The Japanese ground attack

Despite their decision to withdraw air cover, Tokyo was happy to authorise a land-based operation to “expell the invaders.”

Lt. Gen. Michitaro Komatsubara, well schooled officer, planned a devastating two-pronged assault that would encircle and destroy the Soviet armies and bring him a glorious victory.

Japanese infantry at Khalkhin Gol

His Northern task force launched its first assalt on 1st July. After easily crossing the Khalkhin Gol river, Japanse soldiers drove the Soviet forces from Baintsagan Hill and quickly began to advance southwards. The following day his Southern task force followed them with another massive assault.

However, Komatsubara soldiers were ill-prepared, and not able to take advantage of their early success. Poor logistical planning meant that their supply line across the river consisted of just one pontoon bridge.

Soviet Tank Attack Khalkhin Gol

Seizing their opportunity, the Soviets under Zhukov quickly rallied 450 tanks for a daring counter-attack. Despite being entirely without infrantry support, they attacked the Japanese task force on three sides, and very nearly encircled them.

By 5 July, the battered Japanese Northern Taskforce had been forced back across the river.

The second Japanese attack

Following the failure of their first attack, the Japanese withdrew and planned their next move. Defeat was not an option for Komatsubara. After giving his soldiers a fortnight to recover, and restock their supplies, he conceived another assault plan – this one relying on brute force.

On 23 July, backed by a massive artillery bombardment, the Japanese threw two divisions of troops at the Soviet forces that had, by now, crossed the river and were defending the Kawatama bridge. Two days of fierce fighting resulted in some minor Japanse advances, but they were unable to break Soviet lines and reach the bridge. Despite thousands of casualties, the battle was effectively a stalemate.

Unable to progress further, and rapidly running out of artillery supplies, the Japanese decided that discretion was the better part of valour, and disengaged to plan a third assault.

Soviet Counter-Attack

Planning for a third Japanse assault went well, but the Soviets under Zhukov (pictured below, on the right) beat Lt Gen Komatsubara to the punch.

Zhukov Khalkhin Gol

By August 20th, Zhukov had amassed a force of more than 50,000 men, 498 tanks and 250 planes. Matched against him was a similarly sized, but not well armoured Japanese force, that had no idea the Soviet counter-attack was coming.

A classic combined arms assault followed, as thousands of Soviet infantry attacked the Japanese centre, Soviet armour encircled the Japanese flanks, and the Soviet air-force and artillery pounded the Japanese from long-range.

By August 31st, the encircled Japanese force had been decimated and surrounded. A few Japanese units managed to break out of the encirclement, but those who remained followed Japanse martial tradition and refused to surrender.

Zhukov wiped them out with air and artillery attacks.


Khalkhin Gol Ceasefire talksHalf way across the world Hitler and Stalin were putting the finishing touches to their plan to invade and carve up Poland.

Although he was technically an ally of Hitler’s Nazi Germany, Stalin thought it would be prudent to ensure that the Soviet Union’s European flank was also secure.

Poised to finish off the remnants of the Japanese forces, Zhukov’s armies were ordered not to push home their tactical advantage. Instead, they were ordered to dig in and hold their position at Khalkhin Gol – the border they had previously claimed as theirs.

A ceasefire was quickly agreed (talks are pictured above). Implemented on 16 September, it held until the Soviet Union invaded Japan at the end of the Second World War.

How Khalkhin-Gol changed the course of history

The battle of Khalkhin-Gol decisively showed the expansionist Japanese military that it was not a match for the Soviets – particularly while Japanese forces were still bogged down throughout China. The Soviets under Zhukov had combined their forces to stunning effect, while Japanese tactics remained stuck in a pre-modern mindset that valued honour and personal bravery more highly on the battlefield than massed forces and armour.

When Hitler finally invaded the Soviet Union in 1941 the Japanese, although tempted to join the attack, remembered the lessons of Khalkhin Gol and decided to remain on the sidelines, ensuring that the stretched Soviet military could focus its forces on just one front. This, in turn, meant that Nazi Germany was forced to fight a four year war on two fronts – against the Soviets in the East, and the British and Americans in the West.

Defeat at Khalkhin-Gol can also be seen as a major factor in the Japanese decision to expand into the Pacific. As expansion to the North-West was no longer an option, ill defended and scattered colonial territories made far easier targets. Even the United States was deemed a less formidable adversary than the Soviet Union and, if the Japanse had not lost at Khalkhin-Gol, they would surely have never attacked Pearl Harbour.

However, although the Japanese probably took the sensible strategic course after Khalkhin Gol of targetting a ‘weaker’ opponent, they didn’t learn the combat lessons dealt out by the Soviet army. Honour and bravery remained central to the Japanese military mentality and, once they had recovered from the initial onslaught, the United States and Britain were able to mass their forces and push the Japanese out of the Pacific and back to the Home Islands in one brutal battle after another.

Further reading