5-1 The first change in defense policy
5.1.1 Shift of defense policy in the Japanese military
On June 7, the Operations Division of the Navy General Staff called on the Operations Division of the Army General Staff to explain the war situation and to exchange opinions on future operations. At that time, they agreed on the considering the permanent occupation of the western Aleutian Islands [4, p276]. The reason for this was to prevent from establishing Allied bases for air raids on the mainland of Japan. In addition, it was introduced the view by Commander-in-Chief of the Fifth Fleet that "We found to be able to overwinter on both Attu and Kiska Islands. If we are once removed, reoccupying them will be difficult. So we should continue to occupy both islands." [3, p125]. The significance of blocking of linkage between the US and Soviet Union was also taken into consideration.
As a result, on June 23, the Imperial General Headquarters issued the order of the permanent occupation of Attu Island and Kiska Island with Great Army Ordinance No. 647 [4, p277]. As mentioned above, on June 25, the North Sea Detachment came under the direct control of the Imperial General Headquarters [3, p124]. Regarding this policy change, the Japanese War History Series, Senshi Sosho Vol.9 "Pacific War Navy Operation History" also states that "with the opinion of the Commander-in-Chief of the Fifth Fleet and the views of both politics and strategy after the Battle of Midway ..." [ 4, p277]. But that would have required a drastic review of the occupation strategy such as creating air bases. It was quite possible that the US military would build air bases further west of the eastern Aleutian and try to recapture their own territory while threatening the supply line to Kiska and Attu.
The member of Landing Force on board the destroyer "Wakaba" conducted the surveys on Shemya Island and Amchitka Island on June 12. Shemya Island, 50 km east of Attu Island, was found to have dry grasslands suitable for airfields. It was also found that Amchitka Island, 130 km southwest of Kiska Island, had a flat land that could be used as a crash-landing airfield with a little construction [4, p256]. However, the Imperial General Headquarters left both islands unattended (The landing operation of Shemya Island was carried out in November 1942 but was canceled before landing as described later). The fact that Amchitka Island was left unattended and an airfield was built there by the US military in February of the following year became fatal to the defense of the western Aleutian Islands for Japan, as described later.
The Fifth Fleet Command requested the Navy General Staff and the Combined Fleet Command to urgently construct airfields for defense, but both high commands were reluctant to dispatch land airplanes to the western Aleutian Islands. Lieutenant Colonel Tatsukichi Mishiro, who was in charge of aviation at the Imperial Navy General Staff, said, "The purpose of the occupation is to prevent the enemy from using these islands" [4, p298]. This shows the Navy General Staff's belief that the Allied Forces would not attack on these islands if they were occupied by the Japanese troops.
The Navy General Staff underestimated the US counterattack in the western Aleutian Islands and thought that they did not want to involve valuable air power in the attrition warfare. For this reason, the Navy General Staff determined to defend the islands with only ground troops and seaplanes [4, p298]. The permanent occupations of these islands without airbases became the first change in defense policy after landing, which had made the establishment of defense slower than the attack of Allied Forces.
Since the Fifth Fleet command requested the formation of a base corps to the Navy General Staff, the Navy Fifth Guard Corps was established in Kiska Island on July 1, 1942, based on the Navy Third landing Force [4, p280]. However, due to the frequent air raids by US bombers, the Northern Unit again requested the construction of airfield. As a result, the Navy General Staff agreed on June 23 to send investigators for airfield construction of next year. The Combined Fleet Command also changed its mind on July 21 to research the weather conditions this year for considering airfield construction of next year [4, p299]. In any case, there were no plans to build airfields immediately.
Following may be the hindsight-based opinion; If the Japanese military had started transporting materials for airfield and constructing an airfield at this time before the air raids intensified, the Japanese military might have been able to complete an airfield in Kiska Island by the time the US constructed the airfield on Adak Island in mid-September.
Due to the first Japanese policy of occupying the islands by Autumn and the underestimation of US forces, the cannons installed were only four 12 cm cannons, four 7 cm anti-aircraft guns on Kiska Island, and two 7.6 cm cannons and two battalion guns on Attu Island [4, p278]. In response to the unexpected counterattacks by the US air force, the strengthening of defense was immediately considered even though it had just after landed.
To reinforce the defense of Kiska Island, the followings were determined to be sent to Kiska Island by the transport fleet in early July [4, p281]: the Navy Second Landing Force, a field artillery unit, a construction corps, six 15 cm artillery, four 12 cm anti-aircraft guns, four 7 cm field anti-aircraft guns, eight mountain guns, eight anti-tank guns, ten other guns, six midget submarines (Type A Kou-hyouteki-class submarine), and six seaplane fighters.
Along with this transportation, the second interception operation was set up by the Northern Unit. On June 28, the Northern Unit of almost the same force as the previous one, including the aircraft carriers (excluding the carrier "Jun-yo" by the engine trouble), waited at the sea east of Hokkaido [4, p263]. However, the US fleet did not appear, so the two Northern Fleet interception operations by the Imperial Navy had no effect. On the other hand, the transport fleet was targeted by the US submarines near Kiska Island as described below.
5.1.2 Deployment of midget submarines
The transport fleet consisted of the seaplane tender "Chiyoda" carrying midget submarines and the Navy Type 2 seaplane fighters for strengthening the defense, the cargo ship "Aruzenchina Maru", and the destroyers "Arare", "Kasumi", "Shiranui". They arrived at Kiska Island in the fog on July 4. "Chiyoda" and "Aruzenchina Maru" managed to berth in Kiska Bay in the fog, but three destroyers berthed outside the bay. These destroyers were attacked by the US submarine "Growler", which sank "Arare" and wrecked the other two [4, p272].
On July 5, the destroyer "Nenohi" was sunk off the coast of Agattu Island by the US submarine "Triton." As mentioned earlier, on July 1, two submarine chasers were sunk by the US submarine "Grunion" outside Kiska Bay. The soldiers on Kiska Island realized the harshness of the future by the facts that the destroyers and submarines chasers that were supposed to bury submarines were sunk by submarines. However, the Navy Type 2 seaplane fighters and the midget submarines carried by "Chiyoda" were successfully landed. This landing reinforced the various cannons and 350 men of engineering corps for the construction of midget submarine bases.
The construction of the midget submarine base began in July in the midst of the air raid. It took about 3 months to complete a 100-meter slide, a hangar that dug down the coast, and boilers. However, after several training in the bay, all the midget submarines became unusable one after another due to flooding of the submarines due to stormy weather, poor insulation, and the damage to boilers and generators by the bombing [7, p91]. Under the severe weather and the air superiority of US air forces, the midget submarines were never used in any operation.
Three Japanese Type A-class midget submarines wrecked by demolition charges, at a former Japanese base on Kiska Island. (September 7, 1943)
https://ww2db.com/image.php?image_id=3332
The cargo ship "Kano Maru" heading for Kiska Island via Attu Island on July 31 was hit by a torpedo from a US submarine outside Kiska Bay [4, p314]. The next torpedo fired unexploded, so the submarine surfaced because she seemed to try to sink the "Kano Maru" in a gun battle. "Kano Maru" fired an 8 cm cannon in front of her, and the shell hit the submarine's command tower and sank the submarine [4, p327]. This sunken submarine has been recently identified as the US submarine "Grunion". However, in the United States, it is speculated that her sinking is by a damage to the elevator due to the torpedo launched by herself [14]."Kano Maru" was towed into Kiska Bay and was trying to repair it, but she was laid down on September 15 by the air raid.
Attu Island was out of the attack range of US bombers, so no anti-aircraft unit was deployed. However, seeing the situation on Kiska Island, the Imperial Army decided to deploy an anti-aircraft company on Attu Island. Four 7 cm anti-aircraft guns, five 20 mm anti-aircraft guns and about 40 freight vehicles were landed on Attu Island on August 17. However, there were no roads on Attu Island, so the vehicles were hardly available [7, p103]. Moreover, due to the change in defense policy immediately after this as described later, most of the vehicles were abandoned at the removal from Attu Island in September, except for a few vehicles such as tow tractors and ammunition vehicles [7, p104].
5.1.3 Install of radar on Kiska Island
The Navy 1-Gou radar (the first type) was sent to Kiska Island, and the large antenna was installed on the summit of the mountain called Katsura-Yama in August. The radar was supposed to have the detection range of 100 km, but was actually able to capture aircraft 300 km away [7, p239]. The operation unit of the radar was not composed of military personnel but of civilian employees and engineers who had graduated from industrial schools or radio communication schools. Using their expertise and experience, they could detect enemy aircraft from the reflected waveform on the cathode ray tube and reported it to the air defense unit.
Their report was very useful for ground soldiers to evacuate before the air raid. The anti-aircraft units also listened to the course of the enemy airplanes, waited for them with preparing, and shot down them where the enemy aircraft emerged over the mountain [7, p248]. Furthermore, the seaplane fighters took off first after being contacted by the air defense unit, and then headed for interception in the air according to the radio instructions of the enemy's position [7, p212].
Some members of radar unit stated that the radar was believed by soldiers who didn't know it as a super-large telescope that could see everything. Not only were they able to reliably capture the enemy airplanes, but around February 1943, from the waveform reflected on the cathode ray tube, they could know whether the target was bombers or fighters by aircraft type [7, p241].
The radar antenna on Kiska Island was guessed to have caught the US military's attention, but the antenna of the radar was not attacked even by the numerous air raids. The production amount of the Navy 1-Gou radar was about 30, and some of them were also sent to the battle fields in South Pacific, but the one on Kiska Island performed best [15, p94]. It is worth noting that in the early stage of the war, the Japanese troops succeeded in constructing the effective interception system using radar. It is regrettable for Japan that the system was used for the seaplane fighters and the number of them was quite small.
5.1.4 Activities of anti-aircraft units and seaplane fighters for defense
The six Navy Type 2 seaplanes transported to Kiska Island by the seaplane tender "Chiyoda" immediately fought the air battle with the B-24 bomber on July 8. They contributed to the defense to some extent together with the anti-aircraft units. The 7 cm field anti-aircraft gun (Army Type 88 75 mm AA gun) deployed by the Imperial Navy on Kiska Island was inherited from the Imperial Army. However, taking advantage of the fact that the Army and Navy had the same type of anti-aircraft guns on Kiska Island, the information and ammunition possessed by both were unified. The training was also carried out in cooperation with them, so the guns were operated efficiently [7, p226]. It was unusual elsewhere in the Japanese military.
Captain Seiichi Kakizaki, Chief of the Fifth Guard (Deputy Officer of the Navy Third Special Landing Force), stated that the Army's 7 cm field anti-aircraft gun was the suitable gun that was very easy to use and more agile than the Navy's 12 cm anti-aircraft gun [7, p229]. The Imperial Navy did not have this size of anti-aircraft guns including ships. This type of gun also defended the ship from the air raid. Captain Asazo Wada, the commander of the Imperial Army 22nd anti-aircraft gun company, installed three 7 cm field anti-aircraft guns on the transport ship "Boruneo Maru" when his company was deployed to Kiska Island. He then coordinated in advance with the captain of the ship how to navigate when enemy planes came to attack. As a result, they succeeded in destroying the US bombers at sea, and the "Boruneo Maru" could arrive safely on Kiska Island [7, p111].
The Navy Type 2 seaplane fighter (Rufe) was a floatplane developed based on Navy Type Zero fighter and was equipped with 20 mm machine guns. However, US bombers such as the B-17 and B-24 were faster than this, so Navy Type 2 seaplane fighters could not hit more than three times. Therefore, even if it could damage them, it was difficult to shoot them down [7, p212].
After the opening of the US Army Air Base on Adak Island in September, the Navy Type 2 seaplane fighters fought with US Army fighters such as P-39, P-40, and P-38. The speed of Navy Type 2 seaplane fighter was slower than that of Navy Type Zero fighter due to the large float attached, but the turning performance increased due to its buoyancy. Pilots of the Navy Type 2 seaplane fighter on Kiska Island included veterans with excellent skills, and it was said that the US fighters challenged the Navy Type 2 seaplane fighters only when they were superior [7, p213].
As the results of the air battle until August 15, one B-17 bomber and one seaplane reconnaissance aircraft were shot down. One B-17 and one B-24 bomber were damaged. There was no damage to the Japanese pilots [4, p297]. By September 15, the results of battle were five shot down and two destroyed, and the Japanese seaplane fighter had two unreturned and two damaged [4, p308].
The Navy Type 2 seaplane fighter (Rufe)
https://ja.wikipedia.org/wiki/%E4%BA%8C%E5%BC%8F%E6%B0%B4%E4%B8%8A%E6%88%A6%E9%97%98%E6%A9%9F#/media/%E3%83%95%E3%82%A1%E3%82%A4%E3%83%AB:A6M2-N_Rufe.jpg
At that time, the production of Navy Type 2 seaplane fighter was from 10 to 20 per month, and the deployments of them were on Kiska Island and islands in the south Pacific. In the Navy Type 2 seaplane fighter unit on Kiska Island, the aircraft was exhausted in battles and stormy weather, and repeatedly replenished. The replenishment of it was carried out at most once a month on a seaplane tender. As there were some periods when there were no fighters in operation, so the interception on Kiska Island was limited. The seaplane unit on Kiska Island was formed as the Fifth Air Corps on August 5, and became the 452 Navy Air Corps in November.
5.1.5 Bombardment on Kiska Island by US fleet
As the US military considered that the bombing by large bombers was not be effective by clouds, they boldly planned to carry out the bombardment by warships for Kiska Island. The fleet consisted of five cruisers, five destroyers, and four minesweepers had left Kodiak for the attack scheduled on July 23, but it turned back near Kiska Island due to a fog. The fleet had set sail again on July 27, but again encountered a thick fog and turned back. Along the way the destroyer "Monaghan" and the minesweeper "Long" collided in the fog, and the minesweepers "Lumberton" and "Chandler" also collided [10, p41]. These four ships returned to Kodiak and took several months to repair.
Major General Theobald of the North Pacific Force transferred control of the North Pacific fleet to Brigadier General William Smith on August 3, according to the direction by Admiral Nimitz [2, p46]. On August 8, the US fleet led by Brigadier General Smith, which was consisted of the heavy cruisers "Indianapolis", "Louisville", light cruisers "Honolulu", "St. Louis", "Nashville", and four destroyers, approached Kiska Island. The day was cloudy and foggy. The fleet once rushed into the coast using radar, but lost their position due to the fog, so it returned offshore [10, p41]. The fleet launched the reconnaissance seaplanes to survey the fog near Kiska Island. They confirmed the fog cleared, then approached the island again and fired [8, p19].
There were ten cargo ships, four submarines, and one light cruiser in Kiska Bay. The US fleet took the position of southwest of the peninsula called South Head, southwest of Kiska Bay, because the Japanese destroyers were wary of the entrance to the bay. The fleet was unable to aim directly into Kiska Bay behind the peninsula, so it fired by indirect pointing [8, p19].
Fifth Ground Corps in Kiska had just been warned by Northern Unit as the US troops landed on Guadalcanal Island in the South Pacific on August 7, the day before. However, the attack on this day by the US fleet on Kiska Island was due to fog, not in line with the landing operation on Guadalcanal Island. This attack was a surprise attack for the Japanese troops. The Japanese troops noticed the enemy fleet's approaching after discovering the US reconnaissance seaplanes in the sky, and immediately after that, they received heavy naval gunfire [7, p128]. Since the US reconnaissance seaplanes were intercepted by the Japanese seaplane fighters over Kiska Island, one was shot down and three or more were damaged. The Navy Type 2 seaplane fighters also shot the US destroyer "Case". In addition, The Navy Type 97 large flying boats bombed the US fleet from above the clouds, but the US fleet was not damaged [2, p46].
The US fleet fired 7,000 5-8 inch shells. From the second half, the air raids by bombers were also carried out to support the evacuation of the fleet. However, the damage to Kiska Island was only one seaplane fighter damaged and two soldiers killed in action [4, p290]. As a result of later air reconnaissance, the US military determined that although it sank one destroyer and one cargo ship and damaged one cargo ship, it had little effect on ground troops. However, it was not clear whether those damages were due to this naval gunfire or the previous bombings [10, p44]. Brigadier General Smith thought that air strikes were more effective than naval gunfire. Buckner, on the other hand, was wondering the Theobald's undaring instructions for bombing from high altitudes [2, p47].
5-2 The second change in defense policy
5.2.1 Relocation of Attu's garrison to Kiska Island
For the Japanese, the US counterattack on Kiska Island was faster and more powerful than expected. The bombing and naval gunfire on Kiska Island seemed for the Japanese that the Allied Forces would focus on the recapture of Kiska Island. The landing on Guadalcanal Island by Allied Forces also caused concerns about the defense of Kiska Island [3, p146]. The Fifth Fleet command raised the opinion to the Imperial General Headquarters that it would be difficult to secure the western Aleutian Islands for a long time in this situation. The Imperial General Headquarters decided to move Attu Island's garrison to Kiska Island in order to unite and strengthen the defense. It was the second change in defense policy.
On August 25, the Imperial General Headquarters ordered the North Sea Detachment on Attu Island (Attu's garrison) that they relocate to Kiska Island and enter under the command of the Commander-in-Chief of the Fifth Fleet. The advance team of the North Sea Detachment departed for Kiska Island on the transport ship "Nagata Maru" on August 26. However, the transfer of the main troops by the transport ship "Imizu Maru" took time due to stormy weather. In addition, another transport ship "Nojima Maru" assigned to the transfer had been wrecked by the air raid on Kiska Island, so the transfer was delayed. The relocation of Attu's main troops was completed by two separate transports on September 11 and 18. When the North Sea Detachment relocated, they took the part of barracks panel to Kiska Island. However, they burned the rest of the wooden materials, food, and anything else that could be utilized by the enemy on Attu Island [3, p147].
Following the change in defense policy, on September 15, the Imperial Navy formed the Navy 51st Base Force on Kiska Island and appointed Maj. Gen. Katsumi Akiyama as the commander [4, p339]. The Imperial Army occupied Attu Island in November again, but the abandonment of Attu Island and the incineration of most of materials delayed the construction of defense facilities after the reoccupation, which became one of the reasons that the Attu's garrison was wiped out in a short period of time in May 1943.
5.2.2 Occupation of Adak Island by the Allied Forces
The Unite States concerned that Japanese troops would build an airfield on Amchitka Island and occupy Adak Island (400 km east of Kiska Island). Residents of Alaska were also worried about the Japanese invasion to the east. To prevent this, General Dewitt, Commander-in-Chief of the Western Army, felt the need to advance bases west. Buckner of the army Alaskan Defense Force proposed to build an air base on Tanaga Island (300 km east of Kiska Island) and once obtained the approval of the Joint Chiefs of Staff of the United States.
However, Theobald of the North Pacific Force opposed this, saying it was too close to Kiska Island, and directly appealed to Ernest King, Commander-in-Chief of the United States Fleet, to build a base on Adak Island [5, p14]. Eventually, George Marshall, Chief of Staff of the United States Army, instructed Dewitt (and Buckner ) to occupy Adak Island [16, p14]. Due to the controversy involving the Joint Chiefs of Staff of the United States, the operation to occupy Adak Island was delayed by about a month.
The Allied Forces landed the reconnaissance unit on Adak Island on August 28, confirming the absence of Japanese troops, and then landed 4,500 Army soldiers on August 30. On the same day, the engineer corps also landed. They leveled the ground with bulldozers, dug a ditch, and drained water. Mesh iron plates (38 cm x 3 m) of sixty thousand, called Marston mats, were laid there in haste to construct a runway. Due to the extraordinary efforts, the 1500 m long and 150 m wide runway was completed on September 12 [10, p53]. However, due to the runway built on poorly drained land, when it rained, high sprays were generated every time the aircraft took off and landed.
On August 28, a Japanese reconnaissance seaplane found a light cruiser and a destroyer in Nazan Bay, Atka Island. On the next day, three Japanese seaplanes attacked on Atka Island, but there were no ships there. They bombed the berthed flying boats, but they were not damaged.
Three Japanese submarines, "Ro-61", "Ro-62", and "Ro-64", were also ordered to attack on Nazan Bay. The submarine "Ro-61" entered Nazan Bay and hit a cruiser with a torpedo [4, p302]. However, "Ro-61" was forced to surface by the depth charge attacks by the Catalina flying boats and the destroyer "Raid", and was sunk by the bombardment of the destroyer. Five of her crew were rescued by the destroyer and taken prisoner of war [2, p49]. The cruiser "Ro-61" attacked was the seaplane tender "Casco", and she was disabled in the bay by the hit of torpedo, but she was towed back to Dutch Harbor [8, p21]. In addition, the submarine "Ro-62" reported the discovery of the US fleet, so the commander of the Northern Unit prepared for the attack by the US fleet, but the movement of the US fleet was not to attack the Japanese troops but to land on Adak Island.
On September 4, the fighter planes raided Kiska Island for the first time. They were P-38 fighters from Fort Glen Air Base [3, p154]. The Japanese troops suspected that the US military might advance their air base to the west because short-range land fighters had attacked on Kiska Island. The Japanese might not have known P-38 had a long range. However, because there was no air raid after that, the Japanese troops did not notice that Adak Island had been occupied. The US military deployed 15 B-24 bombers, 15 P-38 fighters, and 16 P-39 fighters on Adak Island on September 13 [10, p53]. The base on Adak Island was subsequently expanded to the large base with 9,000 soldiers and personnel.
5.2.3 Air raid with fighter escort
The US air forces made the large-scale air raid on Kiska Island from Adak Island on September 15. The air-raid alarm was issued in advance because the radar on Kiska Island had caught the enemy airplanes. However, this was not the bombing by a small number of bombers until then, but the first large-scale bombing with 12 B-24 bombers and 28 P-38 and P-39 fighters joining the escort. Moreover, the tactics were changed to make the bombing effective; the bombers bombed from low altitudes instead of high altitudes [2, p50].
The bombing and shooting damaged the cargo vessel "Nojima Maru" [4, p307], damaged two submarines "Ro-63" and "Ro-68", and also destroyed land facilities [4, p341]. Four Navy Type 2 seaplane fighters intercepted shot down of five enemy airplanes [4, p313]. Meanwhile, two Japanese seaplane fighters were shot down and one was wrecked. According to the US materials, their damage was the loss of two P-38 fighters that collided in the air [2, p50]. The air battle left only one seaplane fighter on Kiska Island for the Japanese air force.
The US air force tried to expand the outcome, but the aircraft could not fly for the next 10 days due to the bad weather. Meanwhile, the relocation of the Attu's garrison to Kiska Island was successfully completed. However, when the weather improved, large-scale air raids took place on September 26, 29, and 30. On September 26, the submarine "Ro-67" was damaged by the bombing in Kiska Bay [4, p341]. On October 1, a Japanese reconnaissance seaplane finally found the US air base on Adak Island [4, p331]. The Japanese seaplanes air-raided the air base on Adak Island on the night of October 2 and 3 [4, p332]. The submarine "Ro-62" and the submarine "Ro-65" also attacked on Kuluk Bay in Adak Island, but neither was able to get results [4, p341].
The Japanese military seems to have been surprised at the sudden appearance of the air base on Adak Island. However, the Japanese military's response to the advance of the air base to Adak Island was only the replenishment of seaplane fighters and the transport of facility materials and ammunition for air defense to Kiska Island [4, p334].
The establishment of the US air base on Adak Island had significantly increased the frequency of air raids on Kiska, and the fighter support to US bombers had made it difficult to intercept by the seaplane fighters. On September 25, the "Kimikawa Maru" replenished Kiska Island with six seaplane fighters and two reconnaissance seaplanes. However, in the battles after the September 26, there left only one seaplane fighter on October 4, and one reconnaissance seaplane on October 10 [4, p340]. The Fifth Fleet command had requested the further replenishment of seaplane fighters, but the production could not keep up with the exhaustion. Nevertheless, the number of seaplane fighter assigned on Kiska Island was increased to 12, and the commander of the Northern Unit decided to transport five seaplane fighters and three reconnaissance seaplanes to Kiska Island on October 13 [4, p336].
On October 7, the cargo ship "Boruneo Maru" was laid down by the bombing in Gertrude Cove on Kiska Island. The submarine chasers were also damaged on October 9 and 10, and the vessels temporarily left Kiska Island [4, p334]. In addition, a large amount of land supplies and ammunition on Kiska Island were burned down in the air raid on the October 15 [4, p334].
After this, destroyers began to be used for transportation. However, on October 17, the destroyers "Oboro" and "Hatsuharu" carrying ammunition were attacked by six B-26 bombers north of Kiska Island. As a result, "Oboro" sank and "Hatsuharu" was damaged [4, p334]. For the transport using destroyers, they entered Kiska Bay at night and were forced to unload in a short period of time [4, p338].
Moreover, on October 26, the cargo ship "Keizan Maru" loaded with supplies to Kiska Island was sunk by the US submarine S-31 in Suribachi Bay, Paramushir Island [2, p50]. The activities of US submarines had also become active around the northern Kuril Islands.
The Japanese troops on Kiska Island needed solid underground shelters to withstand the large-scale bombings that are expected to continue. Kiska Island troops stopped constructing the defense facilities and began excavating the underground air raid shelters. From the investigation of bomb marks, the underground pit was installed at a depth of 10 m or more [7, p141].
The materials for construction such as drifters were urgently transported by the destroyer "Wakaba" on October 16 [4, p337]. The construction tools of the Japanese troops were only rock drills, pickaxes, and shovels. The excavation of hard rock under the tundra was extremely hard work for them. The soldiers had no choice but to endure the US air raids in the underground shelters. However, thanks to the air raid shelters, they were able to avoid suffering serious damages.
In mid-October, the US fleet again planned to bombard Kiska Island. However, at that time, the battles around Guadalcanal Island in the South Pacific were being culminated, and the US Navy had to pull out several cruisers from the Aleutian area. As a result, the naval gunfire for Kiska Island was ceased [8, p22]. In December, some of the remaining ships were also diverted to the South Pacific, leaving the North Pacific fleet with only two light cruisers, four destroyers and a few torpedo boats, excluding submarines [4, p399]. Although another naval gunfire on Kiska Island was not realized, the US Navy's fighting sprit in the North Pacific seems to have been high and aggressive.
5-3 The third change in defense policy
5.3.1 Review of the defense policy
Since October, Kiska Island had been exposed to the air raids by fighters and bombers, and US Navy vessels have frequently appeared nearby. The construction of airfield on Adak Island strengthened the sea and air attacks on Kiska Island. On the other hand, the Japanese military had no means to counter them, and the situation of transportation to Attu Island and Kiska Island became difficult. Moreover, due to the tense war situation in the South Pacific, it was difficult for Japan to reinforce the naval power toward Aleutian.
On October 8, information was exchanged with the Army and Navy at the Imperial General Headquarters. The situation judgment there was as follows: "The US military is trying to weaken the power of the Japanese forces by cutting off the long supply line. It may not be possible to be invaded soon due to the operations in the South Pacific, but it is likely that the invasion by Allied Forces will take place next spring. Therefore, the Japanese military needs to prepare it by the end of March" [4, p356]. It should be noted that at this point the Imperial General Headquarters had already expected invasions by Allied Forces of the next spring.
The commander of the Navy 51st Base Force on Kiska Island proposed to capture Adak Island. He also requested the reinforcement of land planes and submarines if that was difficult. The Fifth Fleet Command upheld the proposal of the Navy 51st Base Force, but they decided that it would be difficult to capture Adak Island. The Fifth Fleet Command requested to the Navy General Staff the reinforcement according to the proposition by the Navy 51st Base Force. However, the Navy General Staff only replenished seaplane fighters and deployed additional two submarines and two destroyers to the Fifth Fleet [4, p358]. The Fifth Fleet command thought that no matter how much ground troops were strengthened, it was difficult to stop the enemy's invasion without deployment of air forces. Rather, the Fifth Fleet Command was considering retreat from the Aleutian Islands during the winter months [4, p358-359].
Although the Navy General Staff did not agree with the dispatch of land planes, the atmosphere in the Navy General Staff changed to the construction of airfields, partly due to the demands of the Fifth Fleet [4, p362]. On the other hand, the Combined Fleet command continued to consider securing only by ground troops. The Combined Fleet command was inactive to the situation around Aleutian Islands because they were busy responding to the Solomon Islands, which was the main battlefield.
On October 12, the chief of the second section of Army General Staff, who saw the attitude of the Navy, said, "I think it is necessary to secure the Kiska area. The ideas within the Navy are scattered and complicated, and I hope they should resolve this." [4, p360]. Rather, from around this time, the Imperial Army began to place more importance on the western Aleutian Islands as a key point for the battle between Japan and the United States and the prevention of US-Soviet alliances [3, p167].
Although the Imperial Army once abandoned Attu Island, they thought it would be possible for US to build an air base on Attu Island using its high construction ability. The Navy also believed that the construction of an air base on Attu would endanger Kiska Island [3, p168]. The Navy General Staff had the meeting on October 14 regarding the defense of the western Aleutian Islands, and around October 17, they were decided to secure Attu Island again [4, p364].
On October 21, the meeting was held in Ominato between the Fifth Fleet Command, Lieutenant Colonel Sakuo Mikami, Chief of Staff of the Imperial Navy General Staff, and Major Ryuzo Sejima, Chief of Staff of the Imperial Army General Staff. There is no record left on this meeting, but it is speculated as follows: The Fifth Fleet thought that the withdrawal during inactive winter months of aircraft should be considered, and increasing only ground troops without taking adequate measures to retain the western Aleutians would increase supply, which would make rather be at the enemy's discretion [3, p169].
However, the Navy General Staff proposed as follows: Withdrawal would allow the enemy to construct air bases and advance further west, so the Japanese military should regain Attu Island and build airfields on Attu Island and Kiska Island by February of the following year [3, p170]. The idea was different from that of the Fifth Fleet, but it seems that the Fifth Fleet was convinced by the proposition of airfield construction by the Imperial General Staff [4, p359]. This was the third change in defense policy since landing.
The commander of the North Army Force was replaced by Vice Admiral Kiichiro Higuchi on August 1. He is also famous for having tens of thousands of Jews escape to Shanghai via Harbin in Manchuria when he was there. The North Army Force was not in charge of the Aleutian area at that time, but he had interests and raised the war plan for the area to the Imperial General Headquarters. For this reason, the Imperial General Headquarters dispatched a northern research team headed by Maj. Gen. Matsujiro Kimura to Kiska Island in September to collect information for defense. The debriefing session for the research team was held on October 26 at the Army General Staff Headquarters. The report of it properly suggested the important points, so I will summarize some of them [3, Appendix No,8] .
Judgment of the situation in the direction of "Aleutian"
The enemy's invasion is most likely next spring and we needs to be prepared by next March.
The enemy's tactics is block of our long supply line for reduction our strength by direct bombing.
The invasion is unlikely to be surprise attacks, and they will reduce our strength through artillery fire and bombing and then will directly assault.
Setting of defensive zones
Airfields are necessary for defense.
Amchitka Island is relatively flat, especially along the coast of Constantine Harbor. However, there are many swamps, so considerable construction efforts are required.
There are two sites suitable for airfield at the eastern end of Shemya Island.
Construction of a 100m x 800m runway on Kiska Island will take about 70,000 man-days.
Defensive facility
It seems cruel for soldiers to defend only with defense facilities without airfields. If so, the soldiers will only atrophy and become even more disadvantaged.
Hearing the results of the debate at this debriefing session, Major general Toichiro Mineki, the commander of North Sea Garrison (Hokkai Shubitai; details are described later), wondered the military's idea to complete both the airfield construction and the fortification by April-May next year. He also felt that there was a lack of consideration of the weather conditions on Attu Island in conducting various operations [3, p171].
5.3.2 Reoccupation of Attu Island
Abruptly, on October 18, the information came in that the Allied Forces had occupied Amchitka Island. This was a false alarm, but the cause is said to have been announced by US radio broadcasts [4, p364]. At the time, the policy of occupation of Attu Island again had already been decided, so the Imperial Army hurriedly ordered the North Army Force to reoccupy Attu Island (Great Army Ordinance No. 706) on October 20.
Approximately 600 men, including the Northern-Kuril-Fortress Infantry extracted from the North Army Force, led by Lieutenant Colonel Hiroshi Yonekawa, were transported by three light cruisers, "Abukuma", "Tama", and "Kiso". They landed on Attu Island to reoccupy on October 29 [4, p347]. In addition, about 520 men of the anti-aircraft artillery unit gathered from the Western and Eastern Army Forces were reinforced to Attu Island on November 12 by the cargo vessels "Dou-baa (Dover) Maru" and "Dairin Maru" [3, p176].
In order to secure Kiska Island and Attu Island, the Imperial General Headquarters newly established the Army "North Sea Garrison" on Kiska Island on October 24, under the command of Maj. Gen. Juichiro Mineki, and put it under the command of the Fifth Fleet. The Imperial General Headquarters decided on November 1 the following "Army and Navy Central Agreement" [4, p366]:
・ Build a group of air bases consisting of Kiska Island, Attu Island, and Shemya Island by around February 1943.
・ Establish an air base for seaplane on Attu Island
・ The Army builds air bases and the Navy cooperates in transporting its materials
・ Advance fortress infantry to Attu Island
・ In the future, Amchitka Island may be occupied depending on the situation.
However, the last meant only postponing the occupation of Amchitka Island [3, p168]. The North Sea Detachment became the independent infantry battalion and entered under the North Sea Garrison. The newly established North Sea Garrison was provided with construction materials, telephones, dynamite for airfield construction, winter clothing, rain cloaks, rubber boots, etc. [3, p173].
On November 10, Army North Sea Garrison command, including the commander Maj. Gen. Juichiro Mineki, arrived on Kiska Island on the destroyers [4, p347]. The meeting was held with Maj. Gen. Katsumi Akiyama, commander of the Navy 51st Base Force, and the policy for strengthening defense was decided. It was confirmed that the Army would build the complex defense zone including the airfields on Kiska, Attu, and Shemya by the end of February, and that the necessary materials for this were needed to be transported by early December [3, p181]. At the meeting, it was argued that, without air superiority, the U.S. military would be activated after March next year, and that if the US military occupied Amchitka Island, it would be extremely difficult to defend Kiska Island.
The Japanese military had begun to strengthen the defense of the western Aleutian Islands in earnest. In accordance with the aforementioned Army and Navy Central Agreement, the transport of a large amount of materials and an operation to occupy Shemya Island near Attu Island were planned to be implemented by the end of December. However, since the US air force built the air base on Adak Island, Attu Island was also within the range of air raids from there. On November 6, "Kimikawa Maru" ferried five Navy Type 2 seaplane fighters and three reconnaissance seaplanes to Attu Island, but all of them became unusable on the next day due to the storm and the US air raids. The cargo ship "Cheribbon Maru", which arrived at Attu Island on November 27, was laid down by the low-altitude bombing by one B-24 bomber and four B-26 bombers [3, p187].
The Shemya Island capture fleet, consisting of the light cruiser "Tama", the destroyer "Hatsushimo", and the army cargo ships "Montrile Maru" and "Yawata Maru", left Paramushir on November 24. However, it was judged difficult to land on Shemya Island due to seeing the damage of the "Cheribbon Maru" on Attu Island, so the occupation operation of Shemya Island was canceled on the November 28 [3, p187]. When the false alarm of the occupation of Amchitka Island by US troops, it was even said by some Japanese officials that if Amchitka Island could not be retaken, the defense policy in this area should be fundamentally reconsidered [3, p167]. However, since the cargo ship was damaged on Attu Island, the occupation of Shemya Island even near Attu Island was canceled. The neglect of Amchitka Island and the suspension of the occupation of Shemya Island became to bring the major crisis to the defense of Kiska and Attu Islands in next May.
(to be continued)