General situation Before the outbreak of the Japan-Soviet war, the Japanese military's deployment was divided into the northern area (Shikika and Esutoru districts) and the southern area (Toyohara and Maoka districts). The 125th Infantry Regiment was stationed in the northern area, and the main force of the 88th Division was in the southern area. Both were tasked with conducting defensive operations in a prolonged battle, either against the Soviet Union or the United States. The northern area was covered by tundra, and the transportation network was underdeveloped. From the border to the vicinity of Kamishikika Station, there was essentially one military road and railway, making it easy to predict the enemy's course. The 88th Division, on-site, had been requesting a reorganization to focus more on the Soviet threat since late June. Finally, on August 3, they received permission to intercept in case of a Soviet invasion. On August 9, the Soviet Union declared war on Japan, but the order for the Soviet 16th Army to invade Sakhalin came on the night of August 10. The operation plan was divided into three phases: In the first phase, the 1st brigade (primarily the 79th Rifle Division and the 214th Tank Brigade) would break through the border security line. In the second phase, they would capture Kotono Station, which was considered a "fortress", and in the third phase, the 2nd brigade (primarily the 2nd Rifle Brigade) would rapidly advance to occupy South Sakhalin. Two brigades from the border area were the main axis, and supplementary amphibious operations were planned at Tōro and Maoka (Holmsk). After the restraint order was lifted, the 5th Area Army instructed the 1st Air Division's 54th Fighter Squadron to advance to Ochiai Airfield, but bad weather prevented the operation. Meanwhile, Soviet aircraft also struggled with the weather but managed to provide ground support. On August 13, the 5th Area Army decided to send reinforcements—three battalions from the 7th Division in Hokkaido—and even planned a counter-invasion of North Sakhalin (scheduled for August 16). However, on August 15, following the acceptance of the Potsdam Declaration, an order was issued from the Imperial General Headquarters to cease active offensives (Order 1382). The 88th Division on-site initiated a defense mobilization on August 9 and began recruiting special defense forces. On August 10, a combat command post was established at Kamishikika, with several staff members sent. By August 13, the National Volunteer Combat Teams were also summoned. The recruitment of volunteer combat teams from among the general populace was unique to the Sakhalin campaign, with the aim of giving the appearance of military readiness to deter the Soviet advance. The division learned of Japan’s acceptance of the Potsdam Declaration on August 15 via the imperial broadcast. At 4 pm on August 16, the Imperial General Headquarters issued Order 1382, directing all military forces, including the 5th Area Army in Hokkaido, to cease combat immediately, except for defensive actions in case of an enemy attack before ceasefire negotiations were established. The deadline for this order was within 48 hours. However, on August 16, when the Tōro landing operation began, the 5th Area Army’s Commander, Major General Kiiichiro Higuchi, ordered the 88th Division in South Sakhalin to continue fighting and block the Soviet advance, issuing a command to defend South Sakhalin at all costs. From the Soviet perspective, the Emperor's announcement of Japan's acceptance of the Potsdam Declaration was viewed as a general surrender. They maintained that Japan was still resisting and that it would only be considered a true surrender when the Emperor commanded the military to cease combat and lay down their arms. Despite this, both sides were willing to engage in ceasefire negotiations. Japan demanded that Soviet forces halt their occupation at the current positions, warning that further advances would be met with resistance. The Soviet Union, adhering to its demand for unconditional surrender, was determined to push forward and continue occupying the territory. Cherevko (2003) argues that the continuation of combat by Japanese forces in both Manchuria and Sakhalin led the Soviet forces to intensify their attacks. On the other hand, according to Nakayama (2001), the reason the Soviet Union persisted with the invasion of southern Sakhalin was to prevent Japan's retreat from Sakhalin and secure bases for the eventual occupation of northern Hokkaido. Civilian evacuation and road destruction work were carried out under the guidance of the division staff who advanced to Kamishikika, with the Special Security Unit and local security units in charge. The Soviet military’s invasion from the central military road began around 5 a.m. on August 11. The frontline at Handa, defended by about 100 men (two infantry squads and 28 Border Police officers), held off the Soviet advance for an entire day with the support of tanks and aircraft before being nearly completely destroyed on August 12. This death-defying resistance raised the morale of nearby Japanese forces, while the Soviets were shocked to record Handa as a fortress with field fortifications—though in reality, it was a minor defense consisting of a few light covers and anti-tank obstacles utilizing the embankments of the Handa River, and trenches were insufficient due to the wet tundra. Around midday on August 12, Soviet forces from the 179th Rifle Regiment, having broken through the tundra area from the Musuka region, began advancing towards Furuton but were momentarily stopped by a charge from the 2nd Battalion of the 88th Transport Regiment armed with training wooden guns and bayonets. Moreover, the 5th Army's order to cease aggressive attacks, issued on August 9, had reached the 125th Infantry Regiment by this time, restricting its tactics. On August 13, the Soviet 79th Rifle Division launched a siege attack on the 125th Infantry Regiment, combining the main forces on the military road and the flanking 179th Rifle Regiment. Despite the Japanese army's anti-tank guns, Soviet tanks were not destroyed, and the defenders at the Shishiha positions along the military road suffered heavy losses and were forced to retreat. However, the main force of the Soviet 1st Division, shocked by the fierce resistance, only managed to advance a few hundred meters before transitioning into defensive positions. Fierce fighting continued between the 1st Battalion of the 125th Infantry Regiment and the 179th Rifle Regiment around the barracks in Furuton, but by the evening of August 16, Japanese forces were driven into retreat after the deaths of Major Sadaharu Kobayashi and the battalion's deputy, Lieutenant Colonel Iwakai. On August 16, the Soviet main force resumed a general attack, deploying artillery pieces like the 213 artillery units and succeeded in opening the military road to Furuton. However, they were unable to capture the key position of Happo Mountain. On August 17 and 18, a ceasefire order reached the 125th Infantry Regiment’s headquarters from the division, but fighting continued. On August 18, Colonel Kobayashi sent a messenger and agreed to surrender. The 125th Infantry Regiment laid down their arms and ended combat at 10 a.m. on August 19. After the surrender of the 125th Infantry Regiment, the Japanese command in the Northern District was effectively assumed by the staff of the 88th Division stationed at Kamishikika. During the fighting on the central military road, by the morning of August 17, evacuation of the civilian population from Kamishikika had been completed, and the town was burned to the ground by Japanese forces' scorched earth tactics, along with an air raid by 20 Soviet aircraft. Kamishikika was abandoned on August 20, marking the start of a full retreat. The construction of a defensive line involving the destruction of the Uro Bridge and the Chidori River Bridge was considered but ultimately abandoned due to the presence of evacuees. As described earlier in the #General Situation, negotiations between the advancing Japanese division commanders and Soviet forces resulted in a ceasefire agreement on August 22. Additionally, separate from the central military road, Soviet forces launched an invasion on the western coast at Anbetsu, Nishi Saku Tan Village, on August 12. However, the 125th Infantry Regiment’s Anbetsu detachment (one company), supported by civilians, countered the Soviet attack. The Anbetsu detachment, after receiving a ceasefire order from the regiment's headquarters on August 20, refused to surrender and, absorbing personnel from other units, marched southward with about 500 men. Upon reaching the northern part of Nagoyama Town, the detachment disbanded, changed into civilian clothes, and took independent action. Some succeeded in reporting to the 5th Army Headquarters in Hokkaido. The losses sustained by the Japanese forces in the Northern District amounted to 568 killed, mostly due to the battles around Furuton. The Soviet losses remain unknown, but Japanese estimates suggest 1,000 killed and dozens of tanks destroyed. However, the Toyohara Naval Attaché Office remained behind to protect civilians.
August 16: Tōro landing operation (Hama District)
Tōro landing As part of the second-phase operation, the Soviet forces planned the Tōro landing operation near Esutoru Town, the second-largest city in southern Sakhalin. From August 10 onward, Esutoru Harbor and Tōro Harbor became targets for the Soviet Northern Pacific Fleet's air attacks. On August 13, reconnaissance was conducted by torpedo boats and cutter boats, which determined that there was minimal defensive strength. At that time, several boats from ships offshore Esutoru Harbor headed south toward Hama District, but were repelled by the gunfire of the Special Security Unit 301, which forced them to retreat. The landing was originally planned to coincide with a land invasion, but Admiral
Vladimir Andreyev of the Soviet Northern Pacific Fleet decided to act independently and initiated the landing on August 16. Near Esutoru and Tōro Town, when the war began, there was only one company of the 125th Infantry Regiment and some rear units stationed. After the Soviet invasion of Anbetsu, the threat of an attack from the Hondo-Anbetsu line arose, so on August 14, the 25th Infantry Regiment sent one regular company (with a machine gun squad) and a training company of rookie soldiers (equipped with a mountain gun) to reinforce the area. Additionally, the Special Security Unit 301, the 8th Special Security Team from Toyohara District, and a volunteer combat unit (including 600 student soldiers and 80 women) were mobilized. Colonel Kenzo Tomizawa, stationed temporarily at the Toyohara District Headquarters, was appointed as the commander. The Japanese forces deployed two regular infantry companies along the narrow path from Esutoru city to Upper Esutoru to establish a defense line, while one squad from Special Security Unit 301 (with 40 volunteers attached) was tasked with destroying the Tōro airfield and guarding Tōro Harbor, while the remainder assisted in evacuating civilians in the city. Many civilians evacuated to Upper Esutoru, and only about 20% remained when the Soviet forces landed at Tōro. The Japanese forces misidentified the Soviet reconnaissance on the 13th as a full-scale landing and believed they had successfully repelled it with fire from the Special Security Unit. However, this misinformation led to panic in the town of Tōro, with rumors circulating on the 15th that the Soviet forces would land soon. Soviet aircraft, flying with the sun at their backs, would arrive silently, and it was always when a Soviet plane appeared that someone would die. This was a common Soviet tactic of low-level attacks, which could be accurate but also highly dangerous, even against armed forces. However, against unarmed civilians, the pilots no longer required bravery.
Japanese forces' movements At this time, the residents of Esutoru criticized the military for fleeing first. According to Colonel Yasuo Suzuki, chief of staff of the 88th Division, a special security unit was formed from 200 local veterans, and three additional companies were quickly sent to the Esutoru area upon hearing that the enemy was attempting to land on the 13th. Major Tadashi Yoshino was appointed as the overall commander. However, Suzuki believed that if the Soviet forces launched a full-scale landing, the situation would be hopeless, so he instructed that the defense be moved to Upper Esutoru, located 24 kilometers inland on a mountain. Suzuki also claimed that the Special Security Unit should have already retreated to Upper Esutoru by the 16th, arguing that this was a combat strategy. When Yoshino arrived in Upper Esutoru, he found the soldiers unwilling to surrender their guns, and in order to avoid unnecessary conflict, he had them withdraw to the Baiun Gorge, a watershed area. There, they sheltered in the mountains to avoid endangering civilians fleeing, but on the 24th, after receiving orders from division headquarters, they surrendered to the Soviet forces. The route from Tōro to Esutoru was called the "Straight Road," located in a tundra area with shrubs and flowers, 4 kilometers south. Nakagaki's unit, consisting of the Special Security Unit and the volunteer combat unit, halted the Soviet 2nd and 3rd Naval Infantry Battalions advancing south from Tōro and launched a counterattack, forcing them to retreat. The Soviets set fire to the factory to cover their retreat, but the wooden barracks quickly burned down, and the fleeing Soviet forces were destroyed by Nakagaki's unit. Afterward, Nakagaki’s unit escorted the 400 evacuees from Esutoru and arrived in Upper Esutoru by 3:00 am on the 17th. However, other volunteer units in the city failed to execute orders effectively, possibly due to poor communication. At 7:00 am on August 17, the Soviet forces occupied Esutoru's city center and, by 10:30 am, took Hama District. According to Soviet records, there was fighting in Esutoru on the 17th, though it is believed that no regular Japanese forces remained at that point. However, there is limited information available on the actions of the volunteer units, and much remains speculative. On 24 August, when they reached the vicinity of Neiro, a liaison officer from the divisional headquarters arrived and communicated the order to surrender, and the troops accepted the disarmament. The resistance of the volunteer units on the straight road beyond Esutori was fierce, and the Soviet troops withdrew with many casualties. Before the Soviet attack, there had been an incident in which the volunteer troops executed Koreans on suspicion of spying, and eight members of the volunteer troops were later shot dead by Soviet troops on this road on that charge. Some Japanese have suggested that this was revenge for the Battle of the Straight Road. On the 20th, Chief of Staff Suzuki of the 88th Division had the first negotiations with the Soviet forces. However, bound by the order to defend Sakhalin from the 5th Far Eastern Army, Suzuki insisted that the Soviet forces refrain from occupying southern Sakhalin, while the Soviet forces insisted on the occupation and full surrender of the Japanese forces. The ceasefire negotiations were unsuccessful. The Japanese soldiers who had been disarmed at Shika were confirmed to have arrived near Mooka Station on the same day, as confirmed by the testimonies of station personnel. This suggests that, at this point, the Soviets may have believed that the entire Japanese division had already surrendered or was in the process of surrendering. Meanwhile, the Japanese were using Mooka Port as a point for repatriation to the mainland, with the town overflowing with over 15,000 local residents and evacuees. The 25th Infantry Regiment had its main forces stationed for defense, but most of the preparations, such as the burning of military flags and the discharge of older soldiers, were already completed. Only the 1st Battalion of the 25th Infantry Regiment had set up positions on the coast, but on August 16, soldiers were withdrawn from the coastal positions and urban areas and moved inland to camp near Arakeizawa Valley, waiting in reserve. The remaining forces near the city included gendarmerie, a small machine gun and regimental artillery unit, and a few army maritime troops. The "War History Series 44 – Northeast Area Army Operations 2: Defense of the Kuril Islands, Sakhalin, and Hokkaido" (1971) discusses how even after the August 15th end of the war, the 5th Far Eastern Army continued to receive orders from General Higuchi to defend Sakhalin, essentially keeping the defense efforts active. The main routes from Mooka to Toyohara were the Toyohara Mountain Road and the Toyohara Railway. When the Soviet forces landed at Mooka, they would use these routes to move towards Toyohara. The main battle occurred at Kumosa Pass with the 1st Battalion deployed at Arakeizawa. There was some criticism from Mooka residents regarding the absence of military forces in the town. The 25th Infantry Regiment's 1st Battalion Commander, Major Yoshio Nakagawa, explained to the War History Room at the Ministry of Defense that the decision was based on the assumption that Soviet forces would be peacefully occupying the area, and they wanted to prevent civilian casualties in case of unexpected situations. Furthermore, Regiment Commander General Yamazawa reported that the 1st Battalion's 2nd Company was preparing for disarmament on the morning of the 20th. Despite this, the order to continue defending Sakhalin was not widely known at the time.
Soviet forces' landing at Moaka In the early hours of August 20, several Soviet ships appeared off the coast of Moeka. Around 6:00 am Japan time (according to the "War History Series", Soviet records indicate it was around 6:30 am), a Soviet naval convoy, escorted by one patrol vessel and one minesweeper, began their landing at Moeka, firing a salute (blank shots). The Soviet forces, having encountered a torpedo boat that had run aground in the shallow waters and was fired upon with live ammunition by the Japanese forces, responded with naval gunfire. The Japanese side, however, recorded witnessing the boat’s grounding but did not return fire. At that time, Lieutenant Hirose, who was in charge of the regiment’s artillery unit in the Arakaisawa area, observed the Soviet fleet's appearance off Moeka early in the morning on the 20th and saw landing boats charging forward, but despite making contact by phone, he was told that shooting was prohibited and could not engage. However, there were testimonies from soldiers of the 1st Machine Gun Platoon dispatched to Moeka that the platoon leader ordered live rounds in response to blank shots, and letters sent to the battalion adjutant by soldiers of the 25th Infantry Regiment indicated that Japanese forces may have initiated the live-fire response. According to Takatoshi Michishita's post-war account "Reflections on Moeka Town during Soviet Occupation," Soviet soldiers initially landed leisurely on small boats while laughing, but as Soviet warships fired blank shots, Japanese forces began live-fire attacks, and a shelling battle ensued. Former Sakhalin newspaper editorial director Ryuuji Hoshino and Hokkaido Shimbun’s Moeka branch chief Yasuji Fujii are also said to have confirmed these accounts. (In fact, almost all able-bodied men were temporarily detained in coastal warehouses.) Some speculate that the Soviet forces, thinking of air raid shelters as fortified positions, may have attacked them without properly checking who was inside, using gunfire or grenades. There are many testimonies of such incidents, and it is said that clearly identifiable bodies were found. Nevertheless, aside from the 10 members of Hirose’s unit stationed in the northern suburbs, Moeka Town was also defended by one mountain artillery squad and two anti-aircraft machine guns for port and air defense, and Special Guard Unit 305 was responsible for security. Additionally, about 30 soldiers of the Akatsuki Unit (a naval transportation unit) and about 40 air defense watchers, totaling over 100 but fewer than 200 soldiers, were stationed in the town. As soon as the shelling started, it is believed they quickly fled. In Michishita’s memoir "Reflections on Moeka Town during Soviet Occupation," he writes that Mayor Takahashi, dressed in national clothing and wearing gaiters, was mistaken for a soldier and shot. The envoy consisted of 13 men, including guard dogs, and to prevent unforeseen events in the thick fog, sentries were posted every 50 meters. Lieutenant Takahashi Shin of the 2nd Company was perplexed as to why so many soldiers were assigned to the envoy, and upon hearing of their deaths, expressed regret, suspecting that the envoy had, from the beginning, entered Soviet-controlled territory under the guise of ceasefire negotiations and had planned to ambush Soviet officers, starting a battle or attempting an escape. He surmised that the Japanese military had no intention of truly negotiating a ceasefire. Regarding the dispatch of the military envoy, former Regimental Commander Yamazawa later stated in response to inquiries from the War History Room that he had not ordered it and believed it was Nakagawa's independent decision. He acknowledged, however, that even if it was done unilaterally, it was a reasonable measure, and Nakagawa admitted that it was, indeed, his own decision. However, the statements regarding the use of the Guard Duty Order are based on earlier testimonies (which mistakenly referred to Article 11, Paragraph 2). The 1971 War History Series widely publicized the orders from Army Commander Higuchi to defend South Sakhalin. Soviet forces executed several men caught in the fires, paraded their bodies before other prisoners, and then disposed of them by throwing them into the sea. On August 22, Toyohara also came under airstrike, with the area around the station square, where evacuees had gathered, being bombarded with incendiary bombs, resulting in over 100 casualties and the destruction of 400 homes. The airstrikes began around 11:50 am, shortly after a train had arrived, continuing for about 20 minutes. After the occupation, the Soviets attempted to prevent the repatriation of Japanese citizens and property to the Japanese mainland, and on the 23rd, they announced a ban on moving off the island. On the 24th, the Soviet forces occupied Toyohara, the capital of Sakhalin Prefecture, and by the 25th, with the landing at Odomari, the occupation of southern Sakhalin was completed.
On self-defense combat The term "self-defense combat" did not exist as an official term before this. In international law, there is a term for "self-defense war," which includes battles for territorial defense. However, when the Imperial General Headquarters used this term, combat continued against the Soviet forces in Manchuria, and it was intended to apply only if attacks occurred during ceasefire negotiations, assuming surrender under the Potsdam Declaration. This was a step beyond the earlier orders to cease active combat, limiting it to defensive war. The testimony of Colonel Nakagawa, made when Commander Higuchi's order to defend Sakhalin was not publicly known, was based on disarmament and the assumption of Soviet forces' occupation. This self-defense was closer to the concept of self-defense or emergency escape in criminal law. However, Major General Yasuo Suzuki of the 88th Division asked Lieutenant Iwai of the General Staff about self-defense combat. Iwai replied that in a military occupation, there was a risk of confiscation of residents' property, but in the case of occupation, international law protected residents' property, and thus, the proper procedure was to wait for an official ceasefire agreement by the government (not the military), not to continue fighting to halt the enemy's advance. In fact, the situation was quite different. Article 43 of the Hague Regulations on Land Warfare (as referred to in the Hague Regulations) states that during a ceasefire (referred to as a suspension of hostilities), the occupying power must respect the current laws of the occupied territory to the greatest extent possible. Article 46 further ensures the protection of private property. Rather than regarding the situation as an occupation, the terms of a ceasefire agreement or peace treaty would define reparations, territories, and other aspects, regardless of the occupied areas. It is noted that Lieutenant Ito, who was not familiar with this issue, gave his personal view on the matter and did not confirm it with higher commands or the division itself. The Ministry of Defense (at the time) War History Room in the "War History Series" does not comment on the correctness of Ito's argument, nor does it address Article 46 of the Hague Regulations. Here is the translation of the passage into English with the Japanese references retained.
August 22–23: Disarmament and end of combat The Soviet supreme commander informed the Kwantung Army in Manchuria that combat was still ongoing in Sakhalin. On August 21, a telegram from Shigeharu Asao, a staff officer at the Imperial General Headquarters who was on a business trip to Manchuria, arrived at the General Headquarters and the 5th Area Army in Sapporo, stating, "If combat continues under the guise of self-defense, the soldiers of Manchuria and the Northeastern regions will suffer unimaginable hardships thereafter". While efforts were made to conceal the involvement of the 5th Area Army, Major General Hoshikoma's post-war testimony suggested that the failure to cease combat was not their responsibility but rather that of the Soviets. Despite this, the Kwantung Army in Manchuria continued to send telegrams, claiming that they would face retaliation if they did not stop the fighting. The General Staff also sent a telegram warning that continued fighting would hinder the processing of the end of the war. Meanwhile, the local forces in Sakhalin were still acting aggressively, boasting about their victories and showing no intention to stop the combat. All these developments seemed to place the blame on others for the continued conflict. Initial post-ceasefire investigations indicated that 137 men of the 88th Division had died in the Battle of Moji, but later investigations estimated the total casualties to be over 300. On the morning of August 23, Soviet forces launched a combined naval infantry brigade (three battalions) from Moji, which landed at Odomari on August 25 via the Hon-to route. There was no resistance from the Japanese military, and naval bases like the Odomari base were occupied. Additionally, the small airfield at Konotoro, located north of Moji, was occupied by Soviet Navy paratroopers who performed an emergency landing on August 22. == Aftermath and casualties ==