100: Opening Phases


The summer of 1939, near the Mongolian village of Nomonhan, would see the largest clash between the Soviet Union and Japan of the interwar years, and it would have important ramifications for relations between the two nations as the world was rapidly descending into war.


  • Anti-Russian and Anti-Soviet Subversion: The Caucasian-Japanese Nexus, 1904-1945 by Hiroaki Kuromiya and Georges Mamoulia
  • Japanese Geopolitics and the Mongol Lands, 1915-1945 by Li Narangoa
  • Khalkin-Gol: The Forgotten War by Amnon Sella
  • The Lake Khasan Affair of 1938: Overview and Lessons by Alvin D. Coox (1973)
  • Soviet-Japanese Confrontation in Outer Mongolia: The Battle of Nomonhan-Khalkin Gol by Larry W. Moses (1967)
  • Nomonhan: Japan Against Russia, 1939 by Alvin D. Coox
  • Nomonhan, 1939: The Red Army’s Victory That Shaped World War II by Stuart D. Goldman


Hello everyone and welcome to History of the Second World War Episode 100, Nomonhan Pt 2 - Opening Phases. This week a big thank you goes out to Jose who has decided to become a member, gaining access to ad free versions of all of the podcast episodes plus special member only episodes roughly every month, head on over to historyofthesecondworldwar.com/members to find out more. As this is episode 100, and as I know that many listeners are waiting for the actual European phases of the Second World War to start on the podcast, here is a look at the road ahead: This episode today starts a 3 episode series on the fighting around Nomonhan in the summer of 1939, fighting that would overlap with the German invasion of Poland in September of that year. Then in episode 103 we will start at 5 episode series I have tied “Europe Goes to War” which will focus on the events of the summer of 1939 as Europe moved closer and closer to war, covering topics like the growing tension in Danzig, the British and French Guarantee of Polish borders, and preparations for war around the continent, that will be episodes 103 to 107. Then episode 108 will be an episode of reflections on all of the first 107 episodes of the podcast, looking at the events during the interwar period at a higher level to discuss themes, trends, and to once again consider the question of whether or not the war was inevitable. Then in Episode 109, the series of episodes on the German invasion of Poland will begin. If my math is correct, and if I don’t miss any weeks, that means that the first episode on the invasion will be released on August 24th, one week before the anniversary of the start of the invasion. But that is the future, for now we are going to return to the tensions between the Soviet Union and Japan in Eastern Asia in 1939, this time moving away from the Maritime Province and into Outer Mongolia. The fighting that would occur during the battle of Khalkin Gol, or as part of the Nomonhan Incident, would be the largest fighting that would take place between the Soviet Union and Japan during the 1930s. It was larger than the clash during the summer of 1938 at Changkufeng in every way, more troops were involved, they fought over a lengthier period of time, and more of them would become casualties. The results would also have a much greater and more far reaching set of impacts, and it would force the Japanese army to come to the grips with the fact that they were in a bad place when matched up with the Red Army. The overall course of the fighting near Nomonhan would be one of the contributing factors to the eventual signature of the Soviet-Japanese Non-aggression pact which would last for almost the entirety of the Second World War. During this episode we will look at why this remote area of Mongolia became so important, and the early stages of the fighting as the two sides began to slowly increase the resources they were willing to commit to the fighting to try and achieve their goals.

War between Japan and the Soviet Union had been an ongoing concern on both sides for many years before 1939. In the Japanese Army this was driven by the idea that it was the Soviet Union that was the prime threat to Japanese control of Eastern Asia. On the side of the Soviet Union the concern was one of a brewing two front war between the Soviet Union on one side and Germany and Japan on the other. One of the reasons that the Molotov-Ribbentrop pact of 1939 was so surprising to other nations around the world was due to the fact that for most of the 1930s the Soviet Union was one of Germany’s most likely enemies, and no small amount of German official propaganda painted the Soviets as the great enemy. During the early years of the 1930s there had been some discussion of a non-aggression pact between the Soviet government and Japan, but near the end of 1931 the Japanese would reject the proposal. This refusal, and just the general expansion of the Soviet military under the Five Year Plans would result in shift in strength to the Far East, which would be in position to deal with any Japanese aggression. There was also an effort by the Mongolians, who actually controlled the area of the Nomonhan battle, to increase their own military capacity in the last half of the 1930s. This was fully supported by the Soviets, and because it was coupled with a greater Red Army presence it represented a large increase in total military strength. These resources would then be used in 1939 for several very small border fights during the early months of the year. None of these skirmishes were large, but there were probably over 25 of them. The fighting that would occur near the Outer Mongolian village of Nomonhan would be of a completely different type. As with the battle around Chankufeng, this new fight would back place on a piece of disputed territory. In this case a triangle of territory between the village of Nomonhan and the Khalkin Gol river, one small note here, Japanese sources refer to the river as the Halha River, but it is referring to the same thing as Khalkin Gol. This was also one of those areas where there had been some treaties that tried to settle the border disputes during the late 1800s, but those were also imprecise and debate. At its most basic level, the river was roughly 10 kilometers to the West of Nomonhan, the Soviet claimed that they controlled everything from the river to Nomonhan, while the Japanese claimed they controlled everything between the River and Nomonhan, and it would be in this area that the fighting would occur.

While these disputes around where precisely the border was between the two nations was a common cause of friction, there were some additional reasons that this disagreement specifically resulted in such a large confrontation. It comes back to something called Order 1488. This order originated from the Kwantung Army headquarters, because they were generally pretty disappointed in what they saw as the tendency of Japanese front line commanders to be hesitant and overly cautious. The Japanese units were told not to themselves move across the border, but to react far more aggressively if the Soviets tried to move into what was considered Japanese territory. The precise name of the document that was sent out was “Principles for the Settlement of Soviet-Manchukuoan Border Disputes”. They would be presented on April 25, 1939 at a meeting of the Kwantung army high command and divisional commanders. Here is a lengthy quote from the order which touches on some of the most important points: " If the enemy crosses the frontiers … annihilate him without delay, employing strength carefully built up beforehand. To accomplish our mission, it is permissible to enter Soviet territory, or to trap or lure Soviet troops into Manchukuoan territory and allow them to remain there for some time… . Where boundary lines are not clearly defined, area defense commanders will, upon their own initiative, establish boundaries and indicate them to the forward elements… . In the event of an armed clash, fight until victory is won, regardless of relative strengths or of the location of the boundaries. If the enemy violates the borders, friendly units must challenge him courageously and endeavor to triumph in their zone of action without concerning themselves about the consequences, which will be the responsibility of higher headquarters.” There are a few important pieces I want to highlight out of what I just read. First up, the Kwantung Army was putting it on the local commanders to make the decision in instances with poorly defined borders, telling them to establish where those boundaries should be, a very dangerous thing to push all the war down to local army officers. The second is that it contained the words “fight until victory is one, regardless of relative strengths” which essentially meant that not only should local commanders choose where they were going to fight, but that they should then fight to the death. Remember these two items, they will come back later. This order was also forwarded to Tokyo, although there was apparently no response. These orders were received by all Japanese officers in the theater, including by General Komatsubara, the commander of the 23rd division. The 23rd division had only been formed about a year before it would be called to fight at Nomonhan, and it was made up primarily of reservists, fresh recruits, and other personnel who had aged out of front line service in higher quality units. It would be the 23rd that would be in the border regions with the Soviet Union because so many of the best troops had already been sent to China, and there was the desire to keep several of Japan’s best divisions always rested and ready at full strength to meet any serious Soviet aggression. The war with China had already required 7 new divisions to be created in 1938, with the 23rd being one of them, and it would then require 9 more in 1939 with this massive expansion, doubling the size of the Imperial Army, putting pressure on both manpower and equipment reserves. To give the Japanese Army’s own evaluation of the 23rd, it would be rated as “below medium”. While the men had either seen too many winters, or too few, the state of their equipment was even worse. This was again due to the demands of the fighting in China, which meant that most of the non-top of the line divisions did not have their full complement of equipment. All this really meant that the most important unit for the fighting at Nomonhan, would be very unprepared for the ordeal that it would be put through.


The precise events that started the fighting new Nomonhan are, fuzzy. Both sides generally claim that the other was the one that violated the border first, with the Japanese claiming that Mongolian cavalry rode onto their side of the border, while the Mongolian sources, which the Soviet sources agree with, claim that it was actually the Japanese were the ones that made the violation first. The fun part is that both of these facts can be true, because neither side agreed on where the border actually was. The first week of the fighting is generally just a series of very confused events and both sides have stories that do not completely match up. This would later change, as the overall course of events would solidify as larger and larger units were brought into the action, but that only really starts happening after May 17th. What can be generally determined is that the fighting would begin on May 11th when a group of Mongolian cavalry would clash with soldiers from the 23rd division that were positioned to guard the Japanese definition of the border. While this would kick off a major confrontation between the two armies, this incident in the early morning hours of May 11th had happened countless times before on other areas of the border. A small bit of fighting, maybe a few casualties, and then everything would cool down again and go back to normal, but this time it would be different. The catalyst for this change would be Order 1488, because on may 13th General Komatsubara was holding a conference to discuss the order with many of his staff and regimental officers, and it was during this conference that news of the vents at Nomonhan would arrive at the headquarters of the 23rd division. While before there had been some ambiguity about what was expected of Japanese units in this situation, after order 1488 all of that ambiguity was gone, they were expected to “challenge him courageously and endeavor to triumph in their zone of action”. With clear expectations, General Komatsubara made the decision to quickly send two infantry companies, a cavalry troop, and an armored car company into the area under the command of Lieutenant Colonel Azuma Yaozo. This collection of units, generally referred to as the Azuma detachment, would arrive in the area on May 15th. When Azuma arrived he found that most of the Mongolian cavalry had already retreated out of the disputed territory and onto the other side of the river. This information was then relayed to 23rd Division headquarters, and Komatsubara would order Azuma to withdraw, the mission seemingly complete, but it wasn’t. This was because on the 15th Red Army forces would arrive in the form of one battalion of the 149th infantry regiment of the 36th infantry division, and some armor and artillery assets. They would not initially cross the river, which would have brought them into conflict with the Japanese, but some Mongolian troops would cross the river once again on the 17th. When news of this new violation reached Komatsubara he made the decision that such a violation, so soon after the previous event, demanded a swift and decisive response.

To meet the new aggression Komatsubara would send the 64th Infantry Regiment under the command of Colonel Yamagata Takemitsu, and it would be referred to, you guessed it as the Yamagata Takemitsu. It would contain about 800 infantry, an artillery company with 3 75mm mountain guns and four 37mm anti-tank guns, along with three companies of trucks. It would also absorb Azuma’s group when it arrived. All of this gave Yamagata a total strength of roughly 2 thousand men, and he would be given the task of destroying anything he found on the east side of the river, with the attack first scheduled to begin on the 22nd of May, before it was then pushed back to the 27th. The overall plan for the attack was worked out in some detail, and it would share one feature with many of the Japanese plans from the following action, it was by and large far too complex. It would involve Azuma’s unit be separated from the main group, and making an independent advance to where the Halha river met the smaller Holsten river. Then the main body of Yamagata’s forces would be split up into five different attack groups, which would advance in ways that required careful coordination. In theory this could ensure that any Mongolian or Soviet troops that were on the eastern side of the river would be trapped, which would present some opportunities, but it was very risky, especially given the fact that the Japanese had very little idea of what kind of resistance they would be facing. They knew that there were some troops that had recrossed the river on the 20th, but beyond that it was mostly just an empty map. It probably would have worked if it had been met with only week and feeble resistance, which had been the case in several of the previous border clashes, but in this case the Japanese would not come up against a small and easily deterred enemy. What they were facing was a collection of Red Army and Mongolian units which were under the command of Major Bykov. There would be roughly 1,000 men including 16 armored cars, 4 76mm guns, and other assorted equipment. Along with these troops under Bykov, there were also several other units, including reconnaissance units and artillery batteries nearby. The attack would kick off in the early morning hours of the 28th, and there would be some initial success. The Japanese were able in those early hours to take advantage of some key advantages, the first was simply that of numbers, there were many more Japanese than there were those opposing them. They were also able to find quick success against the units of Mongolian cavalry that were in general less equipped to deal with the Japanese attack, they were generally only lightly armed and did not have the equipment backing them up that Red Army troops had access to, but the Japanese advances would begin to slow as they moved closer to the river, because as they moved to the west, they grew closer and closer to the Soviet artillery and various support units of armored cars. This included Azuma’s detachment which was making its run for the bridges over the river. They had expected the bridges to only be lightly held by a few units, but what they found was that it was protected by a Soviet infantry company, a group of combat engineers, and armored cards and artillery. Azuma’s men had nothing with which to deal with the armored vehicles, and they were basically stopped in their tracks. This caused a serious problem, because Azuma had greatly overextended into enemy territory, his goal was to secure the bridges until the rest of the Japanese force arrived under Yamagata. But it was not going to arrive, because the main Japanese attack had also ground to a halt. By mid-day Azuma was already surrounded, and his unit would begin to be attacked from multiple different sides. Azuma, who was under orders to attack and not retreat was determined to hold his ground as long as possible. To make matters worse, the Soviets were bringing additional reinforcements into the fight very quickly, including the rest of the 149th Infantry Regiment, and additional artillery. This made Azuma’s defense hopeless, and as the afternoon wore on the Soviet attackers ground their way closer and closer to Azuma’s units. Then in the evening, understanding that the fight was almost over, Azuma and all of his remaining men led a final charge on the enemy, which was very quickly ended by Soviet Machine guns. Of the men that had attacked with Azuma, several hundred, four would manage to escape the Soviet encirclement, all of the rest were killed or captured.

When the disaster became known at 23rd Division headquarters there was a scramble to push forward more artillery and antitank weaponry, and even some additional infantry on May 29th. These reinforcements allowed the Japanese to partially recover, and to recover 200 Japanese bodies, including that of Azuma, but with a quarter of the original Yamagata force now casualties, the additional forces in no way allowed for a complete transformation of the overall situation near Nomonhan. One thing that worked in favor of the Japanese troops that were in the Nomonhan area was that the transport situation on the Soviet side of the front was abysmal. This would hamper their operations for the entirety of the campaign, because the nearest Soviet rail link was seven hundred kilometers to the west which meant that everything had to be transported by truck or horse cart over that distance. In comparison, the Japanese railheads were around 200 kilometers away, a more manageable distance. To make matters worse the road network in the region, where there even were roads, was not exactly the most optimal for the transport of tons and tons of military goods. There were some attempts to ameliorate this problem over the course of the summer of 1939, but in an effort to build more rail lines faster, the decision was made to use a narrower gauge, which meant that everything had to be unloaded and reloaded onto different rail cars on its way to the front. If it would have just been a few cars a day, maybe no big deal, but at its peak the Soviet and Mongolian forces required 2,000 tons of various material per day.

While the fighting on the ground was only going to ramp up after May, the fighting in the air would be on a similar trajectory. Unlike at Changkufeng, the Japanese would commit air squadrons to assisting the ground units during the fighting, which would be met by a similar commitment by the Red Army Air Force. The early fighting over the battle area was heavily in the favor of the Japanese, due to the fact that the only aircraft in the area for the Soviets were generally the heavily outmatched I-15 biplanes. This resulted in heavy losses for very little gain anytime their aircraft ventured over the river in an attempt to participate in the battle. Eventually the order would be given to halt all air operations, which would still be the case when the Japanese attack was launched on May 28th, which heavily contributed to the early successes experienced by Yamagata’s forces. The balance of forces would very quickly shift in completely the other direction, with more and more Soviet aircraft, and they would be flying newer models. This eventually put the Japanese into the position of being heavily outmatched. To try and gain an advantage in the air the Japanese would launch a bombing raid of Soviet air bases in the area, operations that were not mentioned in reports to Tokyo. The fear was once again that they would be cancelled due to the desire in Tokyo to avoid any kind of wider escalation. When they were launched in late June, and they would actually be pretty successful. They would reach several different air fields and drop 50 kilo bombs, with the Japanese estimates being that 98 aircraft were fully destroyed. The number was almost certainly less than 98. Russian fighter aircraft had been able to take off in some instances, but they were mobbed by the fighter aircraft that accompanied the Japanese bomber formations. While the attack would be judged a success, and would give at lease some level of respite for the Japanese, it would also prove to be yet another heavy blow to relations between the Kwantung leadership and High Command back in the home islands. The general amount of distrust and tension would only increase.