There is a Chinese proverb: "When the roof leaks in the overnight rain, there are always tens of thousands of people beating the broken drum." When the Japanese were losing ground in the Pacific Theater and getting bogged down in the Chinese theater, the Soviets certainly didn't stand idly by.
The atomic bomb was not the only factor that ultimately prompted Japan's surrender. Another factor was also quite important: Japan's proud Kwantung Army was easily annihilated by the Soviet Union. However, after the atomic bomb was dropped, Japan was naïve enough to think that the Soviet Union would mediate. Of course, they were wrong.
In August 1945, the Soviet Union officially declared war on Japan. In addition to the feud between Russia and Japan, a large part of the reason for the war was that the rich mineral and land resources of the northeast region had always made the Soviets salivate. Moreover, helping China to "recover" the northeast is also conducive to supporting a force loyal to itself in China, so that it can help itself against the United States after the war, which can be seen that the Soviets' calculations are quite good.
Although the Soviet Union had absolute military strength, fighting against Japan was definitely not a simple matter. First of all, it is a matter of time, because the main purpose of this operation is to seize the interests in the northeast, so it is necessary to end the battle before Japan surrenders to the United States, otherwise the Soviet Union will act as a "migrant worker" for the United States and China.
Secondly, the area involved in this operation is very large, and the front line is very long. And most importantly, the Japanese Kwantung Army has occupied the tohoku region for fourteen years, and has built many fortifications such as fortresses and artillery towers in the northeast. Next, I will explain the comparison of military strength between the two sides.
The military strength of the Japanese army
The Japanese army was commanded by Army General Otsuzo Yamada, and the Japanese Kwantung Army had the First, Third, and Seventeenth Fronts and the Independent Fourth Army, with a total number of about 970,000 people, plus the puppet army and other dependent countries' total strength of 1.2 million people.
The commander of the Soviet army was Marshal Vasilevsky, with a military strength of 1.68 million people, and the number was superior. The strength of the Japanese was that of the defenders, familiar with the terrain and quite strong fortifications. According to statistics, the Japanese army built seventeen fortification areas in the border area, and there were two aviation units involved in support operations.
However, the shortcomings of the Japanese army are also very obvious, that is, the armor and firepower are seriously insufficient. The Soviets had more than 5,500 tanks and self-propelled guns, compared to just over a thousand Japanese tanks. Moreover, the Soviets had twenty-six thousand artillery pieces, while the Japanese had only five thousand.
As mentioned above, the Japanese army had two air forces involved in the war, with 1,800 aircraft, while the Soviet Union had 5,200 aircraft. Moreover, in most weapons, the Soviet army was far better equipped than the Japanese army. It can be seen that in the comparison of the military strength of the two sides, the Soviet army is slightly superior.
Where is the Soviet advantage
At 00:10 on August 9, 1945, the Soviet army launched a surprise attack on the Japanese army on the long border line of more than 5,000 kilometers between China and the Soviet Union without fire preparation. Such raids rendered many of the fortifications ineffective---- the Japanese did not even have time to enter the fortifications, and the Soviet tanks had already run over them.
The Soviets quickly broke through the Japanese defenses, and the speed of the attack far exceeded the imagination of the Japanese army. On the first day of the campaign, the tank corps advanced 120 kilometers and the infantry corps advanced 50 kilometers. This speed even exceeded the Soviet army's plan, and even logistics were difficult to supply. The advance detachment of the Sixth Tank Army broke into the northeast plain and advanced four hundred and fifty kilometers. Then he was forced to stay for two days because the logistics did not keep up.
At the same time, the First and Second Armies of the Far East also launched an offensive according to the plan. Although the First Army's offensive was blocked in some places, its main force successfully bypassed the fortifications and advanced into the northeast.
The Second Army attacked at 1 a.m., crossing the Heilongjiang River and engaging in a fierce battle with the Japanese in the surrounding counties. The Second Army was the weakest of the entire Soviet Army, and the number of heavy equipment was also the smallest, so it was relatively difficult to fight.
On August 15, the Japanese army was forced to surrender under pressure from many quarters. However, the Kwantung Army did not stop fighting until August 17, when the Kwantung Army officially ordered a truce of the troops, and on the 18th issued an order to surrender. At this time, the Soviets quickly sent mobile troops to take over various strategic points in the northeast region.
Sporadic resistance continued, but the Soviet offensive did not stop. By August 30, the entire Kwantung Army had been completely disarmed and the war had ended.
Summary: According to Soviet statistics, the Soviets captured nearly 600,000 Japanese troops in this battle, the vast majority of whom were sent to Siberian labor camps. More than 80,000 people were killed, nearly 700 tanks, more than 800 aircraft, 1,800 artillery pieces, 15 self-propelled guns, 13,000 machine guns, about 300,000 rifles, and a large number of other military supplies were captured.
On the Soviet side, nearly 10,000 people were killed in battle, more than 1,300 people were killed in non-combat, and nearly 1,000 people were missing. In addition, nearly 20,000 people were wounded in the battle. The total casualties were about 36,000.