Fragile peace in the east
The Japanese Empire fought alongside Germany and Italy on the Axis side in World War II. This bloc is often labeled fascist, yet Japan bore its own traditional, chauvinist nationalism. Despite differing ideologies, the practical aim remained clear: seize as many territories as possible to boost resources and prestige.
During the war, the Japanese met the Red Army as it moved to defend Mongolia, an ally of the USSR, from bases in occupied Manchuria. A heavy defeat at Khalkhin Gol taught Tokyo that a quick clash with the Soviet Union would be unwise, nudging the empire toward a broader war with its partners. The moment came in 1941 when Germany began its invasion of Russia, but the targets shifted: the emperor planned a war with the United States by year’s end. Sanctions cut Japan’s oil lifeline, pushing supply lines toward Southeast Asia, controlled by American allies.
The European fighting ended in May 1945, yet the Red Army did not rest. Right after the German surrender, divisions moved east under an agreement with Western allies: the USSR would strike Japan six months after victory over Germany. A main invasion of the main islands would demand forces on par with the Normandy operation of 1944, something not available to the USSR. The plan instead focused on liberating Manchuria by defeating the Kwantung Army.
A thousand kilometers of kilometers
The Manchurian operation stretched beyond the scope of earlier campaigns. The problem was not enemy strength. The Japanese army could not match the Wehrmacht at any point, and the Kwantung Army had long served as a supplier of equipment and manpower to other fronts. The challenge lay in scale: Manchuria extended from eastern Mongolia to Vladivostok and from the Amur to Harbin, over more than a million square kilometers. Soviet planners expected to seize the vast area within weeks.
To make that possible, the Red Army assembled roughly one and a half million soldiers, 27 thousand artillery pieces, 5 thousand tanks, and 3.5 thousand aircraft. The Kwantung Army, with forces in occupied Korea, nominally reached about 900 thousand, aided by around 200 thousand Chinese collaborators. Many seasoned troops had been moved away to other theaters to repel American actions in the Pacific and to shore up China, leaving behind relatively fresh units. Armament across the line consisted of only 400–500 tanks on a 2,000-kilometer front, with older models like Type 95 and Type 89 barely comparable to contemporary Soviet armor. The infantry faced a shortage of machine guns and anti-tank rifles; anti-tank guns failed to reliably pierce modern armor.
On August 9, the Red Army opened a two-pronged offensive from Mongolia and from Vladivostok, closing around major centers such as Changchun and Mukden (today Shenyang). Smaller pincers spread toward Blagoveshchensk and Chita, reaching toward Qiqihar. Soviet air forces bombed enemy installations, striking headquarters, warehouses, communications hubs, and troop concentrations with little resistance.
The Japanese defense could not halt the breakthrough. Even when anti-tank rifles and explosives were used against armor, measures failed to stop the armored spearheads. The defenders were young, healthy veterans who had fought in Europe, yet the technology gap remained wide. Kamikaze tactics, aimed at tanks, did little to change the outcome. The real struggle lay in keeping pace: fuel, ammunition, and food supplies were the limiting factors for the advance.
To sustain the push, the Red Army dropped air assault units onto Manchurian airfields to receive cargo. Forces landed along the southern Kuril Islands, on Sakhalin, and in northern Korea to speed up movement. In under two weeks, the Kwantung Army collapsed. On August 15, the emperor announced surrender, though some units in Manchuria did not immediately receive or accept the news. Fighting persisted until August 20, with Soviet casualties around 12,000, a figure far smaller than in some other campaigns.
Why should he surrender?
Soviet textbooks often credit the Manchurian operation as the decisive factor in forcing Japan to surrender, while suggesting atomic bombs had limited impact. The success of the campaign in China is studied in military academies worldwide, showing how a determined assault could force a collapsing opponent from the field. Without Japanese capitulation, the USSR would likely have faced a longer struggle, possibly confronting American or Chinese forces on Japanese soil. Japan had long hoped the USSR might broker peace with the United States, so Soviet entry into the war erased that option. Yet the question remains how a nation committed to fighting to the end could end a war so abruptly.
In Japan, surrender carried the weight of nuclear devastation. Conventional warfare no longer appeared viable to many leaders rooted in a belief that cities must not be destroyed by such weapons. Plans for Okinawa had turned the island into a fortress, preparing for a long, brutal struggle if Tokyo faced a direct assault.
After Hiroshima, the Imperial Cabinet debated Potsdam terms. Some leaders doubted the existence of a new weapon; others discussed parity strategies. The Emperor’s own stance came through in comments that time could not be wasted and the war must end to avoid more tragedy. The second bomb over Nagasaki accelerated the decision. A captured pilot later described how a misinformed view of American stockpiles shaped voices in the room. The dialogue reflected fear, not certainty, about what the next days could bring.
When Hirohito spoke to the nation, he framed surrender around the new, devastating bomb and its threat to humanity. He did not dwell on the Soviet campaign in his address, though it surely affected the choice. The joint pressure of the Manchurian defeat and the atomic crisis left little room to bargain. The region watched as a once formidable empire chose to stop the war, allowing new political realities to emerge in Asia and beyond. [Source: Soviet military archives]