Having lost the Russo-Japanese War (1904-05), the emperor in Japan over the Portsmouth Peace secured the transfer to his disposal of the Kwantung Region (Liaodong Peninsula). On this territory it was allowed to have a certain number of troops.
The emerging Kwantung Army helped strengthen Japanese influence in China. In 1931, an urgent reorganization of these troops began. First of all, the number of soldiers increased.
It should be noted that the Kwantung Army was the most honorable military group in Japan. Service in these troops guaranteed promotion through the ranks. The Kwantung army at that time was in some way a base for the training of ground forces.
The Japanese government tried as quickly as possible to implement the plan for the construction of various strategically important facilities on the territory of Manchuria. By the end of the summer of 1945, about four hundred landing sites and airfields, twenty-two thousand automobile and seven and a half thousand railways were built. In addition, barracks were formed to accommodate seventy divisions (about one and a half million soldiers), warehouses for food, ammunition, and other materials were created. All this made it possible to launch full-scale military operations in a fairly short period of time, if necessary.
Due to the fact that Japan considered the Soviet Union to be its main opponent, seventeen fortified regions were created on the border with the USSR. The total length of these areas was about eight hundred kilometers. According to experts, the Kwantung Army could use these fortified areas not only to provide protection, but also to conduct offensive operations.
After unsuccessful military operations on the Khanhin-Gol and Hassan Lake in 1938-39 Japan has taken all necessary measures to prevent conflicts with its northern neighbor. Along with this, the preparations for the war against the USSR continued actively. The command of the Kwantung Army developed a plan for the invasion of the Soviet Union, which was adopted by the ruler of Japan in 1940. However, already in the following year, 1941, the Kontokuen plan was approved (immediately after the invasion of the German troops in the USSR).
The outcome of the Battle of Stalingrad forced the Japanese to abandon their campaign against the Soviet Union. From this moment, the Kwantung Army was somewhat disbanded. By the fall of 1943, the best units of the troops were deployed to the south. The following year, one company of each combat engineer battalion and one battalion of each artillery and infantry regiment were removed from the army. By the summer of 1945, a significant number of tank, engineer, and artillery units had been transferred to Japan and China. The replenishment of troops was carried out at the expense of Japanese settlers (senior stock and recruits). However, the formed six new divisions were not able to replace the withdrawn parts. In addition, the new personnel, as a whole, were not prepared for military operations, and there was no time for training.
By the end of the summer of 1945, the USSR began a war with Japan. The fairly well-trained and mobile troops of the Soviet Army relatively quickly overcame the resistance of the scattered units. The absence of aviation and tanks allowed to enter the territory of Manchuria almost unhindered, which ensured the further defeat of the Kwantung Army.
These troops included about 900 thousand soldiers. At the same time, almost half of them were military personnel of auxiliary units (engineering, convoys, engineer, communications and others). About 90 thousand soldiers died during the hostilities, about 15 thousand died from illnesses and wounds, a small number fled.