In February of 1945, at the Yalta conference, the USSR promised to declare war on Japan three months after the defeat of Hitler's Germany. In exchange for this aid, the Soviet Union would gain Sahalin and the Kuril islands, lost in the Russo-Japanese war of 1904-1905.
At that moment, Japan and USSR had a neutrality pact, signed in 1941, lasting 5 years. In April of 1945, the Soviet Union declared a one-sided annulment of the pact, citing Japan's alliance with Germany and military action against allies of the USSR. “In this situation, a neutrality pact between Japan and the USSR has become meaningless, and there is no point in prolonging it,” claimed the Soviets. The sudden annulment of the pact sent the Japanese government into a panic, and for a good reason. The war situation was becoming critical. Allied forces dealt a series of crushing blows in the Pacific theater. Japanese cities and industrial centers were constantly bombed. No reasonable person remained in the Japanese government that believed in victory. The only remaining choice was to tire out the Americans until acceptable conditions for surrender can be negotiated.
America understood that a victory over Japan would not be easy. A handy example would be the battles for Okinawa. Japan had 77 000 soldiers on the island. America sent 470 000 against them. The island was taken, but America lost 50 000 soldiers. The Minister of Defence estimated that a final victory over Japan without the involvement of the Soviet Union would cost one million killed and wounded.
A declaration of war was handed to the Japanese ambassador at 17:00, on August 8th, 1945. It declared that combat will start the next day. Considering time zone differences, this left the Japanese effectively one hour before the Red Army marched into battle.
The Soviet strategy included three stages: the Manchurian, South-Sahalin, and Kuril. The first stage was the largest and most important, and it deserves a detailed description.
The Kwantung army, led by General Otsudzo Yamada, opposed the USSR in Manchuria. It contained about one million soldiers, over 6000 artillery and mortars, about 1500 planes and over 1000 tanks.
The Red Army started the operation with a pretty significant numerical advantage: 1.6 times as many soldiers, 5 times as many tanks, 10 times as many artillery pieces, more than 3 times as many planes. The advantage was not only quantitative; the Red Army's machinery was significantly more modern and powerful than that of the enemy.
The Japanese understood long ago that a war with the Soviet Union is unavoidable. For this reason, they created numerous fortification regions. Let us examine one of these: the Hailar region, which was to counter the advance of the left flank of the Trans-Baikal Front. Reinforcements were built up for 10 years. In August of 1945, it consisted of 116 bunkers, connected with concrete trenches, and a large amount of defensive engineering structures. This region was held by a division of soldiers.
It took several days to drive the enemy out of this region. This does not seem like a long time, it's not like the troops were stuck for months. However, in this time, other sections of the Trans-Baikal front moved forward as much as 150 kilometers. By the standards of that war, the delay was significant. Even after the main forces of the Hailar region surrendered, separate groups of Japanese continued to fight, showing fanatical bravery. Soviet reports constantly mention soldiers that chained themselves to their machine guns in order to prevent retreat.
Among the Red Army's successful operations, one must pay special attention to the 350 kilometer march of the 6th Guards Army through the Gobi desert and Hingan Mountains. The peaks of Hingan seemed an impenetrable barrier for tanks. Soviet tanks traveled on a road as high as 2000 meters above sea level, on slopes as steep as 50 degrees, forcing the tanks to zig-zag. Conditions were further complicated by nonstop rain, impassable mud, rushing mountain rivers. Regardless, Soviet tanks moved forward. By August 11th, they passed through the mountains and found themselves deep in the rear of the Kwantung army, on the Central Manchurian Plains. The army was lacking fuel and armament, and had to be supplied by air. 900 tons of tank fuel alone was supplied. As the result of this incomparable feat, the Red Army managed to capture 200 000 prisoners, and a large amount of guns and armour.
The First Far-East Front of the RKKA was met with brutal resistance from soldiers entrenched on hills designated “Sharp” and “Camel”, which were included in the Hotou fortified region. The approaches to those hills were swamps, scarred with small rivers and streams. The slopes were covered in trenches and barbed wire. The Japanese carved hardpoints into the mountain granite. Bunkers were covered in concrete up to 1.5 meters thick.
Defenders of “Sharp” rejected all offers for a surrender. The Japanese commander beheaded the local villager used as a translator. The Japanese were always unwilling to negotiate with the Red Army. When Soviet soldiers breached the fortifications, they discovered no remaining people, only corpses. Among them were not only men, but women, armed with grenades and daggers.
In the battle for the Mudandzyan city, the Japanese actively used suicide bombers. They threw themselves on Soviet tanks and soldiers with grenades strapped to them. On one section of the front, 200 of these “living mines” lay down in front of advancing tanks. Suicide attacks only initially had results. Red Army soldiers quickly learned to remain vigilant, and the attacker was usually shot before he could get in range and harm infantry or tanks.
On August 15th, Emperor Hirohito addressed his country by radio, informing the population that Japan accepts the conditions of the Potsdam conference and surrenders. The Emperor called his people to display courage, patience, and unite their strength to build a new future.
Three days later, on August 18th, 1945, at 13:00 local time, a radio message was issued from the Kwantung army general staff to its soldiers, which informed them that the decision to surrender was made, as continued resistance was futile. Over the next few days, forward detachments of the Kwantung army with no radio link were informed by messengers.
Most soldiers accepted surrender without any objections. Furthermore, in the city of Chanchun, where Soviet forces were insufficient, the Japanese themselves guarded military installations. Even so, a small number of fanatical soldiers and officers continued to resist, refusing to accept a “cowardly” order to cease fire. Their war only ended when they died.
On September 2nd, 1945, the act of unconditional surrender of Japan was signed aboard the American battleship Missouri. This date marks the official end of the Second World War.