The 'Battle of Mutanchiang' was fought between Soviet and Japanese forces as part of the Soviet 'Avgust Buri' invasion of Manchuria (12/16 August 1945).

The rapid pace with which the Manchurian campaign was fought and concluded meant that this was one of the only set-piece battles that took place before the end of hostilities. During this battle, elements of Lieutenant General Shimizu Tsunenori’s Japanese 5^th Army attempted to delay the Soviet forces of General Polkovnik Nikolai I. Krylov’s 5^th Army and General Polkovnik Afanasi P. Beloborodov’s 1^st Red Banner Army long enough to allow the bulk of the Japanese forces to retreat to more defensible positions. Although the losses on each side were heavy, the Soviet forces were able to break through the hastily organised Japanese defences and capture the city of Mutanchiang 10 days ahead of schedule, but the Japanese defenders of the city nonetheless achieved their goal of allowing the main forces to escape.

During February 1945, at the 'Argonaut' conference in Yalta, the Soviet leader Iosif Stalin agreed with President Franklin D. Roosevelt and Prime Minister Winston Churchill that the USSR would enter the war against Japan within three months of Germany’s defeat. To meet that deadline, the USSR and the Western Allies co-operated in stockpiling supplies in the Far East, and the Soviet army despatched additional forces to the east along the Trans-Siberian Railway. The Japanese monitored the build-up but believed that the Soviets would not be ready to attack until the middle of September. The Japanese were thus being taken by surprise when the Soviet 'Avgust Burii' strategic offensive actually began on 8 August.

By this time, the Japanese force tasked with defending Manchuria, General Otozo Yamada’s Kwantung Army, had been reduced from the Imperial Japanese army’s most important fighting force to a shadow of its former self. Stripped of most of its heavy equipment and experienced formations for the reinforcement or rebuilding on the Japanese forces on other fronts, it possessed an average efficiency of less than 30% relative to its pre-war capabilities. The Soviets, on the other hand, hand-picked their best formations from the war in Europe based on their experience against certain types of terrain and defences. Key to the defence of eastern Manchuria was Lieutenant General Seiichi Kita’s 1^st Area Army, based at Mutanchiang. Subordinate to the 1^st Area Army were Lieutenant General Noritsune Shimuzu’s 5^th Army and Lieutenant General Murakami Keisaku’s 3^rd Army, and of these it was the 5^th Army which was to play the main part in the forthcoming battle. The Japanese overall strategy in the event of a Soviet attack was for an initial stand to be made near the borders to allow the main Kwantung Army forces to withdraw to a 'redoubt area' around the city of Tunghua but, unfortunately for the Japanese, the necessary redeployments and the fortifications at Tunghua were not ready at the opening of hostilities.

The Soviet strategy, on the other hand, was exactly the opposite. To prevent the Kwantung Army from withdrawing to relative safety, the Soviet leadership under Marshal Sovetskogo Soyuza Aleksandr M. Vasilevsky planned a lightning assault in the form of a pincer movement, which was designed to stun and envelop the Japanese forces before they had a chance to escape. In charge of operations opposite the 1^st Area Army in eastern Manchuria was Marshal Sovetskogo Soyuza Kirill A Meretskov’s 1^st Far Eastern Front, whose objectives were to seize Jilin and to isolate Manchuria from Korea.The implementation of these tasks would take Meretskov’s forces through the vital centres of Mutanchiang and Harbin. Leading the drive to Mutanchiang would be General Polkovnik Afanasi P. Beloborodov’s 1^st Red Banner Army and General Polkovnik Nikolai I. Krylov’s 5^th Army with at least half of their parent front’s combat strength.

The Soviets renounced the Soviet-Japanese Neutrality Pact with Japan on 5 April, and the Soviet forces crossed the border into Manchukuo (Japanese-held Manchuria) at 00.00 on 8 August, achieving both operational and tactical surprise. In response, Imperial General Headquarters ordered all-out military action against the USSR, and the Soviet-Japanese War had begun in earnest.

The initial Soviet thrust was opposed by the 5^th Army's 135^th Division, 126^th Division and 124^th Division, which were driven back by the Soviet attack. The main land routes to Mutanchiang were centred on a pair of mountain passes, one to the north and the other to the east of the city. The Soviets made use of both of these passes, the 1^st Red Banner Army attacking from the north and the 5^th Army from the east. The Soviets were ultimately successful in their advance, but their losses, especially in armour, were very heavy. Of particular concern to the Soviets were concealed anti-tank guns as well as suicide bombers with explosives strapped to their backs: together with the torrential rain, these made the Soviet advance difficult.

By 12 August, the 5^th Army had been compressed into a semi-circle around Mutanchiang. The Soviets continued to gain ground, but the shrinking Japanese lines and their recovery from the initial attack meant that resistance in all sectors was stiffening. Despite showing an ability to recover and repair damaged tanks that both impressed and disheartened the Japanese, the Soviets continued to lose armour: in one sharp action the 257^th Tank Brigade’s original strength of 65 tanks was reduced to just seven. Japanese losses were also severe: on the morning of 13 August, a convoy of troop trains was ambushed by Soviet tanks, which destroyed the trains and killed approximately 900 Japanese soldiers: 30 cars carrying 24 pieces of artillery, 30 vehicles, 800 rifles and 100 machine guns were lost. Among those who barely survived was the commander of the 135^th Division.

Over the course of the next few days the Japanese continued their resistance around Mutanchiang from a series of fortified hills, from which they could rain fire onto the Soviet corridors. The Soviets were forced to take these hills one by one, using their armoured and artillery superiority to neutralise the defences. During the struggle for Mt Shozu, an important Japanese stronghold, the weight of Soviet fire was so great that it appeared as if the top of the mountain had been wholly removed by fire. Suicide bombers and anti-tank guns remained an ever-present threat, however: on 14 August Japanese forces near Ssutaoling knocked out 16 Soviet tanks with direct fire and another five with individual suicide bombers. Nevertheless, these attacks were reliant on the fanaticism of the individual Japanese soldier, and while they resulted in the destruction of Soviet armour, Japanese human losses were much higher.

The unexpectedly strong resistance around Mutanchiang led Meretskov to change the 5^th Army’s objective from capturing the city to bypassing it, and to leave the 1^st Red Banner Army to take the city itself. That move threatened the integrity of the entire Japanese defence, whose situation thus became untenable. On 15 August, Shimizu, acting under the Kita’s authority, ordered the 5^th Army to begin a withdrawal, leaving only minor forces as a rearguard. At 07.00 on 16 August, the final Soviet assault on Mutanchiang began. Rocket artillery shattered the remaining Japanese defenders, while tanks and infantry smashed forward to attack the city itself. However, in attempting to cross the Mudan river to the east of Mutanchiang, the 1^st Red Banner Army found that all three bridges spanning this waterway had been destroyed by the Japanese, and heavy fire from the opposite bank made a landing by boat impossible.

In response, the Soviet 22^nd Division crossed the river farther to the north and surprised the Japanese defenders from behind, which forced their withdrawal. That allowed the bulk of the 1^st Red Banner Army to cross directly over the river and to begin the assault on the central area. By 11.00, Soviet forces had begun the room-by-room reduction of Mutanchiang in the face of continued fanatical resistance. By 13.00, the Japanese rearguard had abandoned the city under pressure from the south, east and north-west, leaving only scattered groups of diehards to continue resistance from the devastated buildings. As the 1^st Red Banner Army invested Mutanchiang, the 5^th Army to the south continued its advance to the west, enveloping and destroying the 126^th Division's 278^th Regiment, whose survivors opted to mount a last-ditch banzai charge rather than surrender. By the end of the day, all Mutanchiang had fallen into Soviet hands, and the battle for the city was over. Shortly after this, the main strength of the Kwantung Army laid down its arms in obedience to the Emperor Hirohito’s surrender broadcast.

Through the speed and the bold conduct of their offensive, the 5^th Army and 1^st Red Banner Army had secured a major victory at Mutanchiang, advanced between 95 and 110 miles (150 and 180 km), and captured their objective a full 10 days ahead of schedule. The rapid advance had pre-empted Japanese plans to establish a strong initial defensive line before Mutanchiang and forced the Japanese to begin their withdrawal early, which fragmented their forces. Despite those successes, however, stiff Japanese resistance and the failure of the main Soviet forces to keep pace with their spearheads allowed the bulk of the 5^th Army to withdraw, albeit at only 50% of its already limited effectiveness. Soviet leaders acknowledged this, admitting the retreating Japanese were still 'a very considerable force'. However, all of that matter little as the war ended before any further major fighting could take place.