This was the Soviet seizure of Manchukuo, Menjiang (Inner Mongolia), the northern portion of Korea, the southern portion of Sakhalin island and, in a subsidiary undertaking, the Kurile islands group in the USSR’s only military offensive of the war against Japan, otherwise known in its main element as the 'Manchurian Strategic Offensive Operation' (9/18 August 1945).
The extremely rapid defeat of the Kwantung Army, which the Japanese believed, though wrongly, to be their premier army formation, had immense politico-military ramifications: the Soviet success was at least as important as the US 'Centerboard' and 'Silverplate' atomic bombings of Japan, and indeed probably more so, in persuading Japan that it could no longer hope to continue to fight the Allied powers. The campaign also served to warn the USA of the advanced strategic, operational and tactical land warfare capabilities of the USSR as a result of the lessons the country had learned in the war against Germany.
At the 'Eureka' inter-Allied conference at Tehran in November 1943, Josif Stalin had agreed that the USSR would enter the war against Japan once Germany had been defeated, and at the 'Argonaut' conference at Yalta in February 1945, Stalin agreed to Allied pleas to enter the war against Japan within three months of the end of the war in Europe. The 'Avgust Buri' invasion began precisely three months after the German surrender: the USSR declared war on Japan late on 8 August and began the invasion, simultaneously on three fronts, during the first minutes of 9 August, a moment which fell between the US atomic bombings of Hiroshima and Nagasaki (6 and 9 August).
The Russo-Japanese War of 1904/05 ended in a major Japanese victory and was terminated by the Treaty of Portsmouth by which, in conjunction with other later events including the Mukden Incident and Japanese invasion of Manchuria in September 1931, Japan steadily gained total control of Korea, Manchuria (which became the puppet kingdom of Manchukuo) and the southern half of Sakhalin island. In the late 1930s there had been several Soviet-Japanese border incidents, the most significant being the Battle of Lake Khasan (the Changkufeng Incident if July/August 1938) and the Battle of Khalkhin Gol (the Nomonhan Incident of May/September 1939). These border conflicts were brought to an end in April 1941 by the Soviet-Japanese Neutrality Pact. This had the great benefit for the USSR of ending the threat of Japanese aggression against it and therefore making it possible for the USSR to concentrate on its war with Germany and transfer combat-experienced formations from Siberia to the Eastern Front, and for the Japanese of being able to concentrate on their southern expansion into Asia and the Pacific Ocean.
However, following its great strategic victory at Stalingrad in January/February 1943, which effectively made the defeat of Germany almost certainly inevitable, the USSR’s attitude to Japan began to became more anti-Japanese as Stalin started to make overt speeches denouncing Japan, and as the Soviet armed forces began a covert programme to increase their manpower, matériel and supplies in the Far East. At the Tehran conference the 'big three' (Prime Minister Winston Churchill, President Theodore D. Roosevelt and Premier Stalin) agreed that the USSR would enter the war against Japan. In this Stalin faced a dilemma, for he wished to avoid a two-front war at almost any cost, yet also wished to extract political and physical advantages in the Far East as well as in Europe. The only way Stalin could make Far Eastern gains without a two-front war would be for Germany to capitulate before Japan. Even so, the last period of the 'Great Patriotic War' was characterised by an initially slow but steadily accelerating enlargement of the Soviet military capabilities in the Far East.
By a time early in 1945 it had become abundantly clear to the Japanese that the Soviets were preparing to invade Manchuria, although in all probability only after the final defeat of Germany. Japan was already very hard pressed in the Pacific and Burma, but realised they needed to establish where and when the Soviet invasion would occur.
At the Yalta conference of February 1945, among the many success he gained over the ailing Roosevelt, Stalin secured US approval for the USSR’s Far Eastern territorial desires in return for an agreement to enter the war against Japanese no later than three months after the defeat of Germany. Despite the manifest longer-term Soviet threat to their possessions in the northern part of east Asia, by March 1945 the Japanese were so pressed in the Pacific theatre that they had perforce to withdraw most of their high-quality formations from Manchukuo for service in the the Pacific.
Meanwhile the Soviets continued the enlargement of their military strength in the Far Eastern. The Soviets had decided that they did not wish to renew the Neutrality Pact and, in line with the pact’s stipulation that notice of this fact thad to be given 12 months before the pact’s expiry, on 5 April the Soviets informed the Japanese that they would not renew the agreement. This caused the Japanese considerable concern, but the Soviets assured the Japanese that the treaty still had 12 months to run and that they had nothing about which to be concerned.
Germany’s surrender came on 9 May (Moscow time), which meant that, in in order to honour their Yalta agreement, the Soviets would have to enter the war against Japan by 9 August. The defeat of Germany left Japanese in a position still more precarious than it had been before this time, for its left Japan as the only Axis power still in the war. In these circumstances Japan wished to remain at peace with the USSR and to extend the Neutrality Pact. Since the time of the Yalta conference, the Japanese had repeatedly approached, or tried to approach, the Soviets in order to extend the neutrality pact, and to enlist the aid of the USSR in negotiating peace with the Western Allies. The Soviets did nothing to discourage these Japanese hopes, and extended the process as long as possible while also continuing to prepare their invasion.
One of the tasks of the government of Admiral Baron Kantaro Suzuki, which took office on 7 April 1945, was to try to secure any peace under any terms short of unconditional surrender. Late in June the Japanese approached the Soviets with the suggestion that the latter should help go negotiate a Japanese peace with the Western, and for their efforts offered the Soviets very attractive territorial concessions. Stalin expressed interest, and the Japanese awaited the Soviet response, which was never made. The Potsdam conference lasted from 16 July to 2 August, and on 24 July the Soviets recalled all their embassy staff and families from Japan. On 26 July the conference produced the Potsdam Declaration whereby Churchill, Truman and Chiang Kai-shek (the USSR not being at war with Japan) demanded the unconditional surrender of Japan. The Japanese continued to wait for a Soviet response, and avoided responding to the declaration.
Throughout this period the Japanese had been monitoring Soviet movements along the Trans-Siberian Railway traffic and also Soviet activity to the east of Manchuria. Taken in conjunction with the Soviet delaying tactics, this suggested to them that the Soviets would not be ready to invade eastern Manchuria before the end of August. However, the Japanese had no real idea about when or where any invasion would take place.
Thus the Japanese were caught completely by surprise when the Soviets declared war an hour before midnight on 8 August 1945, and invaded simultaneously on three fronts just after midnight on 9 August.
The entire Soviet campaign took the form of three primary operations ('Khingan-Mukden Offensive Operation', 'Harbin-Kirin Offensive Operation' and 'Sungari Offensive Operation', each of 9 August/2 September) and three subsidiary operations ('South Sakhalin Army Group Offensive Operation' of 11/25 August, 'Seisin Landing Operation' of 13/16 August and 'Kuril Landing Operation' of 18 August/1 September).
The Soviet authorities had allocated the planning and execution of this vast and fast-moving offensive to Marshal Sovetskogo Soyuza Aleksandr M. Vasilevsky’s Far East Command. The only Soviet equivalent of a complete theatre command in World War II, the Far East Command comprised Marshal Sovetskogo Soyuza Rodion Ya. Malinovsky’s Trans-Baikal Front aimed at Inner Mongolia and western Manchukuo with General Leytenant Aleksei I. Danilov’s 17th Army, General Leytenant Aleksandr A. Luchinsky’s 36th Army, General Polkovnik Ivan I. Lyudnikov’s 39th Army and General Polkovnik Ivan M. Managarov’s 53rd Army, General Polkovnik Andrei G. Kravchenko’s 6th Guards Tank Army, General Polkovnik Issa A. Pliyev’s Cavalry-Mechanised Group, and Marshal Sovetskogo Soyuza Sergei A. Khudiakov’s 12th Air Army; General Maksim A. Purkayev’s 2nd Far East Front aimed at eastern Manchukuo with General Leytenant Makar F. Terekhin’s 2nd Red Banner Army, General Leytenant Stepan K. Mamonov’s 15th Army and General Major Leonti G. Cheremisov’s 16th Army, and General Polkovnik Pavel F. Zhigarev’s 10th Air Army; and Marshal Sovetskogo Soyuza Kirill A. Meretskov’s 1st Far East Front aimed at northern Manchukuo with General Polkovnik Afanasi P. Beloborodov’s 1st Red Banner Army, General Polkovnik Nikolai I. Krylov’s 5th Army, General Polkovnik Ivan M. Chistyakov’s 25th Army and General Leytenant Nikanor D. Zakhvatayev’s 35th Army, General Major Vladimir A. Zaitsev’s Operational Group 'Chuguevsk', General Polkovnik Ivan M. Sokolov’s 9th Air Army, and Konter-Admiral N. V. Antonov’s Amur Military Flotilla. Each front had 'front units' attached directly to the front instead of its component armies.
The Soviet invasion force totalled 89 divisions with 1.685 million men, more than 5,550 armoured fighting vehicles including 3,700 T-34 machines and 1,850 self-propelled guns, 26,135 pieces of artillery, and 5,360 aircraft including 3,700 first-line combat warplanes. Some one-third of this overall strength was in combat support and services. The naval force comprised 12 warships, 78 submarines, many amphibious craft, and the Amur Military Flotilla consisting of eight river monitors, 11 river gunboats and numerous small craft including 52 armoured launches.
Carefully and very competently developed in the months before the operation was launched, the Soviet operational plan incorporated the lessons of all the experience in manoeuvre warfare which the Soviet forces had acquired fighting the Germans.
Malinovsky’s Trans-Baikal Front was the western half of the Soviet pincer movement, attacking across the Inner Mongolian desert and over the Greater Khingan mountains. The Trans-Baikal Front was thus to take Mukden (now Shenyang), then meet troops of the 1st Far East Front at the Changchun area in south central Manchuria, and in doing so complete the planned double envelopment.
Meretskov’s 1st Far East Front was the eastern half of the Soviet pincer movement, attacking toward Mudanjiang (or Mutanchiang) and, once it had taken this, advancing toward Jilin (or Kirin), Changchun and Harbin. Its final objective was to link with the Trans-Baikal Front at Changchun and Jilin, thus closing the double envelopment movement. As a secondary objective, the 1st Far East Front was to prevent the Japanese forces from escaping south-east into Korea, and then to invade the Korean peninsula to a line as fat to the south as the 38th parallel, in the process establishing what later became North Korea.
Purkayev’s 2nd Far East Front had a supporting role, and its objectives were Harbin and Tsitsihar as well as the prevention of an orderly withdrawal to the south by the Japanese forces. Once the 1st Far East Front and Trans-Baikal Front had captured Changchun, the 2nd Far East Front was to attack the Liaotung peninsula and seize Port Arthur (now Lushun).
The Japanese defence was vested in General Otozo Yamada’s Kwantung Army, which was the major part of the Japanese occupation forces in Manchuria and Korea. The Kwantung Army comprised two area armies and two independent armies in the form of General Seiichi Kita’s 1st Area Army in north-eastern Manchukuo and comprising Lieutenant General Keisaku Murakami’s 3rd Army and Lieutenant General Noritsune Shimizu’s 5th Army; General Jun Ushiroku’s 3rd Area Army in south-western Manchukuo and comprising Lieutenant General Shojiro Iida’s 30th Army and Lieutenant General Yoshio Hongo’s 44th Army; Lieutenant General Uemura Mikio’s independent 4th Army responsible for northern Manchuria; and Lieutenant General Senichi Kushibuchi’s independent 34th Army responsible for the areas between the 3rd and 17th Area Armies. There were also the Kwantung Defence Army responsible for Inner Mongolia, and Lieutenant General Yoshio Kozuki’s 17th Area Army responsible for Korea but assigned to the Kwantung Army just before the launch of the Soviet offensive but unable to play any effective role in the defence of Manchuria. The defence of southern Sakhalin and the Kurile islands was vested in Lieutenant General Kiichiro Higuchi’s 5th Area Army.
Equivalent to a western army, each area army had headquarters units and formations attached directly to the area army, in addition to the field armies each equivalent to a western corps.
In addition to the Japanese there was General Zhang Jinghui’s 40,000-man Manchukuo Defence Force, comprising eight incomplete, poorly equipped and badly trained Chinese divisions. Korea, which would have been the next target for the Far East Command, was garrisoned by Lieutenant General Yoshio Uetsuki’s 17th Area Army.
In overall terms, the Japanese had 1.217 million men including more than 600,000 troops in two tank divisions, 25 infantry divisions and four independent mixed brigades. These had 1,155 armoured vehicles (mostly armoured cars and light tanks), 6,700 pieces of artillery (mostly light), and 1,800 aircraft (mostly trainers and obsolete types). The Japanese navy contributed nothing to the defence of Manchukuo, whose occupation it had always opposed on strategic grounds.
Most of the Japanese formations were far below establishment strength as many of their constituent units had been redeployed to strengthen formations depleted in fighting the Americans, British and Chinese farther to the south, and most of Japan’s heavy weapons and equipment had also been transferred out of the theatre to meet the pressing and, at the time, more urgent needs of the Pacific campaign. The result was that the Kwantung Army had in real terms been reduced to a comparatively light infantry force more suited to the counter-insurgency than modern combat role, and possessing only limited mobility and experience. Manchuria had the bulk of usable industry and raw materials for the Japanese in China, and was therefore of primary strategic importance, but the Japanese forces were no match for the Soviet army which had a vast superiority, qualitative as well as quantitative, in terms of its equipment, matériel and tactics by that time. The Japanese forces also contained a large number of new recruits.
At the dictate of Imperial Japanese army headquarters, Korea was given priority defence and the army was oriented along the northern and eastern borders of Manchuria with only limited outposts along the western border.
The Japanese believed that for purely economic grounds Manchukuo was worth defending as it contained most of the usable industry and raw materials outside of Japan and was still under Japanese control in 1945.
Technically, tactically and numerically outmatched by the Soviet forces which were preparing to attack them, the Japanese had also made its own task all the more difficult by making a number of mistakes and erroneous assumptions. Two of these were notably important. Firstly, the Japanese assumed that any attack from the west would follow either the old railroad line to Hailar, or head into Solun from the eastern tip of Mongolia. The Soviets did indeed attack along these routes, but their main attack from the west went through the supposedly impassable Greater Khingan range to the south of Solun and into the centre of Manchukuo. Secondly, Japanese military intelligence signally failed to establish anything approaching the real nature, location and scale of the Soviet strength in the Far East. Based on initial underestimates of Soviet strength, and the monitoring of Soviet traffic on the Trans-Siberian Railway, they believed the Soviets would not have sufficient forces available before the end of August, and that an attack was most likely in the autumn of 1945 or even in the spring of 1946.
As a result of withdrawal of the Kwantung Army’s best formations for redeployment to the Pacific theatre, in the summer of 1945 the Japanese prepared new operational plans for the defence of Manchuria against a seemingly inevitable Soviet attack. The new plans called for the redeployment of the main Japanese strength from the border areas, which would be held lightly and fight delaying actions, while the Kwantung Army’s main strength was to hold the south-eastern corner and in the process defend Korea from attack.
Furthermore, the Japanese had only observed Soviet activity on the Trans-Siberian Railway and along the eastern part of the Manchurian front, and so were preparing for an invasion from the east. They believed that if and when an attack developed from the west, it would be of a scale with which the redeployed forces would be able to cope.
Although this redeployment had been initiated, however, it was not due for completion until September. Thus the Kwantung Army was in the middle of redeployment when the Soviets launched their attack simultaneously on all three fronts.
The Soviet operation was carried out as a classic double pincer envelopment over an area the size of western Europe. In the western pincer, the Soviet forces advanced over the deserts and mountains from Mongolia, far from their resupply railways. This confounded the Japanese military analysis of Soviet logistics, and the Japanese were therefore taken by complete strategic, operational and tactical surprise, and in unfortified positions. The Japanese commander was missing for the first 18 hours of the conflict, and communication was soon lost with forward units: the Japanese forces had been misled into believing that any invasion would take place in October. At the same time, Soviet airborne units were used to seize airfields and city centres in advance of the land forces, and were also used to ferry fuel to units which had outstripped their supply lines.
The fighting lasted for only one week before Emperor Hirohito read the Gyokuon-hoso (imperial rescript) on 15 August, and declared a ceasefire in the region the next day. By this time Soviet forces were already deep into Manchukuo, and persevered with their now largely unopposed advance, reaching Mukden, Changchun and Tsitsihar by 20 August. At the same time, Inner Mongolia was invaded by the Soviet forces and their Mongol allies, with Guihua soon taken. On 18 August, several amphibious landings had been launched ahead of the land advance: three in northern Korea, one in Sakhalin, and one in the Kurile islands.
This meant that, in Korea at least, there would already be Soviet soldiers waiting for the troops coming overland. The land advance was stopped a good distance short of the Yalu river, the beginning of the Korean peninsula, when even the aerial supply lines became unavailable. The forces already in Korea were able to establish some measure of control in the northern part of the peninsula, but the Soviet ambition to take the entire peninsula was cut short when US forces landed at Inchon on 8 September, six days after the signing of the Japanese instrument of surrender.
Hokkaido was not invaded as had been planned. In Sakhalin and the Kurile islands, the Soviet offensives meant the immediate establishment of Soviet sovereignty. In Sakhalin the LVI Corps (79th Division, 2nd Brigade, 5th Rifle Brigade and 214th Tank Brigade attacked the 88th Division. Although the Soviets outnumbered the Japanese by 3/1, they were unable to advance in the face of strong Japanese resistance. Thus it was not until the 113th Brigade and 365th Independent Naval Infantry Battalion from Sovetskaya Gavan landed on 16 August at Toro, a coastal village of western Sakhalin, that the Soviets broke the Japanese defence line. Japanese resistance grew weaker after this landing. Actual fighting, mostly skirmishes, continued until 21 August. From 22 August to 23 August, most of the remaining Japanese units announced a truce. The Soviets completed the conquest of Sakhalin on 25 August 1945 by occupying the main town, Toyohara.
Japanese sources claim that 20,000 civilians were killed during the invasion. Of some 448,000 Japanese residents of South Sakhalin in 1944, a significant number were evacuated to Japan during the last days of the war, but the remaining 300,000 or so stayed behind for several more years, and while the majority of Sakhalin Japanese were eventually evacuated to Japan in 1946/50, tens of thousands of Sakhalin Koreans (and a number of their Japanese spouses) remained in the USSR.
Perhaps even more than the 'Silverplate' and 'Centerboard' atomic bombings of Hiroshima and Nagasaki on 6 and 9 August, 'Avgust Buri' broke the Japanese political deadlock and forced Japan’s surrender, for the three events had made it clear that Japan had no hope of holding out, even in the nation’s 'home islands'. Some historians, particularly Soviet and Chinese scholars, have viewed the loss of Manchuria (and the implicit threat of a total collapse of Japanese power in China as a whole) as a decisive factor in the Japanese surrender, perhaps more important than the atomic bombings. In particular, it is said that the Japanese were eager to surrender to the USA before they were occupied by the USSR.
Soviet-occupied Manchuria would also provide the main base of operations for Mao Tse-tung’s Chinese communist forces, who proved victorious over Chiang Kai-shek’s Nationalist forces in the following four years of civil war in China. In fact, military success in Manchuria prevented the USSR from receiving the bases in China which had been promised by the Western Allies, because all land gained was turned over to the communists after they gained power in China.
Before leaving Manchuria, however, Soviet forces looted its considerable industrial plant and relocated it to war-torn Soviet territory. As agreed at Yalta, the USSR had intervened in the war with Japan within three months of the German surrender, and was thus entitled to the territories of Sakhalin and the Kurile islands as well as to pre-eminent interests over Port Arthur and Dairen, with its strategic rail connections. The territories on the Asian mainland were transferred to the full control of the People’s Republic of China in 1955.