Battle of Nomonhan

The incident began on 11 May 1939. A Mongolian cavalry unit of some 70-90 men had entered the disputed area in search of grazing for their horses. On that day, Manchukuoan cavalry attacked the Mongolians and drove them back across the Khalkhin Gol. On the 13th, the Mongolian force returned in greater numbers and the Manchukoans were unable to dislodge them.

On the 14th, Lt. Col. Yaozo Azuma led the reconnaissance regiment of 23rd Division, supported by the 64th Regiment of the same division, under Colonel Takemitsu Yamagata, into the territory and the Mongolians withdrew. However, Soviet and Mongolian troops returned to the disputed region and Azuma's force again moved to evict them. This time things turned out differently, as the Communist forces surrounded Azuma's force on 28 May and destroyed it. The Azuma force suffered eight officers and 97 men killed and one officer and 33 men wounded, for 63% total casualties.

On 27 June, the Japanese launched an air attack. The Japanese 2nd Air Brigade struck the Soviet air base at Tamsak-Bulak in Mongolia. The Japanese won this engagement, destroying half again as many Soviet planes as they lost, but the strike had been ordered by the Kwangtung Army without getting permission from Imperial Japanese Army headquarters in Tokyo. Tokyo promptly ordered the Japanese Army Air Force not to conduct any more strikes.

Throughout June, there were continuing reports of Soviet and Mongolian activity on both sides of the river near Nomonhan, and small-scale attacks on isolated Manchukoan units. At the end of the month, the commander of the Japanese 23rd Division, Lt. Gen. Michitarō Komatsubara, was given permission to "expel the invaders". The Japanese plan was for a two-pronged assault. Three regiments plus part of a fourth, including three from the 23rd Division--the 71st and the 72nd Infantry Regiments, plus a battalion of the 64th Infantry Regiment--and the 26th Infantry Regiment under Colonel Shinichiro Sumi, "borrowed" from the 7th Division, would advance across the Khalkin Gol, destroy Communist forces on Baintsagan Hill on the west bank, then make a left turn and advance south to the Kawatama Bridge. The second prong of the attack would be the task of the Yasuoka Detachment, consisting of the 3rd and the 4th Tank Regiments, plus a part of the 64th Regiment, a battalion of the 28th infantry Regiment, detached from the 7th Division, 24th Engineer Regiment, and a battalion of the 13th Field Artillery Regiment, under overall command of Lieutenant General Yasuoka Masaomi. This force would attack Soviet troops on the east bank of the Khalkhyn Gol and north of the Holsten River. The two Japanese thrusts would meet in the Soviet rear and encircle them.
The northern task force succeeded in crossing the Khalkhyn Gol, driving the Soviets from Baintsagan Hill, and advancing south along the west bank. However, their advance would slow and eventually be turned back by Soviet forces following a bloody counterattack. Meanwhile, the Yasuoka Detachment (the southern task force) attacked on the night of 2 July, moving at night to avoid the Soviet artillery on the high ground of the river's west bank. A pitched battle ensued in which the Yasuoka Detachment lost over half its armor, but still could not break through the Soviet forces on the east bank and reach the Kawatama Bridge. After a Soviet counterattack on 9 July threw the battered, depleted Yasuoka Detachment back, it was dissolved and Yasuoka was relieved.

The two armies continued to spar with each other over the next two weeks along a four-kilometer front running along the east bank of the Khalkhyn Gol to its junction with the Holsten River. On 23 July, the Japanese launched another large-scale assault, sending the 64th and 72nd divisions against the Soviet forces defending the Kawatama Bridge. Japanese artillery units supported the attack with a massive barrage that consumed more than half of their ammunition stores over a period of two days. The attack made some progress but failed to break through Soviet lines and reach the bridge. The Japanese disengaged from the attack on 25 July due to mounting casualties and depleted artillery stores. They had suffered over five thousand casualties to this point but still had 75,000 men and several hundred planes facing the Communist forces. The battle drifted into stalemate.

The Soviets would launch their next offensive August 20, 1939 to break the stalemate. Soviet attacks started off well but would bog down in the face of concentrated artillery fire. The Japanese would counterattack with 200 tanks and infantry. Nothing positive is gained by either side. The Japanese Air Force successfully cleared the skies of Soviet aircraft though at heavy loss to themselves over several days allowing the Kwantung Army to fight under a neutral sky. Japanese losses, especially infantry, are severe. On the northern flank, the Japanese Border Guards regiment, augmented by recently arrived troops, blunt the main Soviet thrust of attack until sheer numbers force the regiment to pull back. Near Fui, the Red Army broke through using tanks and flamethrowers but were pulled into a trap when newly arrived infantry regiments and artillery pieces force the Communist breakthrough into a box. The Japanese tanks are easily disabled by the superior Russian models, leaving the Japanese no options but Human wave tactics. The 7th Foot Infantry division, one of the recent reinforcements, suffered grievous losses.
By August 26, 1939, Soviet forces had halted their attacks. In four days of battle, 40,000 Japanese and 27,000 Russian soldiers have been killed. Most of the Red Air Force in the region (some 150 aircraft) was destroyed. Only 200 Soviet tanks remained and Japanese air attacks had destroyed the only road and railways from Chita to the Nomonhan threatening the Red Army's supply line. Unsettled by Japanese fanaticism, and their own losses, Soviet forces pulled back to strengthen their defenses for future Japanese assaults.

Both sides would seek an armistice following the bloody and inconclusive Battle of Nomonhan. Though their second major loss in two years, the Japanese, and especially the Kwantung Army, were not to be discouraged.

SOURCE: The Anatomy of a Small War: The Soviet-Japanese Struggle for Changkufeng/Khasan, 1938-1941