4-1 Invasion on Attu Island
The Attu invasion troops arrived outside Holtz Bay (Hokkai Bay) on Attu Island on the night of June 7, and the North Sea Detachment aboard the transport ship "Kinugasa Maru" landed in thick fog at 0010 (almost dawn) on June 8 [3, p116]. The Japanese War History Series, Senshi Sosho "Army Operations of the Northeastern <1>" states that "Unexpected mountains overlaped and no battalion cannons were able to be carried. The map was inaccurate, and it was difficult to determine the direction in the fog, so the troops often went wrong ways" [3, p117].
Although it was June, there was still a lot of snow left, and the march was carried out while trampling on the snow [12]. The troops marched through the snow that remained on the steep terrain and occupied Chichagof Harbor (Atsuta Bay) at 0730. Eventually, 1143 men of the North Sea Detachment consisting of one infantry battalion (1st battalion of the 26th infantry regiment), one company of engineers (a company of the 7th engineer regiment), and the Navy Communications Corps landed [7, p18].
https://ww2db.com/image.php?image_id=18565
No American soldiers were stationed on Attu Island, and the Japanese protected 37 Aleuts and an American radio engineer and his wife by the Japanese War History Series, Senshi Sosho "Navy operations in the Northeastern" [4, p255]. According to the materials on the American side and "Kiska Senki", there were 42 Aleut people who lived on Attu Island [2, p37] [7, p412]. The radio engineer and his wife committed suicide, but her wife survived and was sent to Japan as a prisoner of war [7, p413]. She was the only American citizen who became prisoner of war during the World War II.
The Japanese troops set the border with the Aleut settlements and lived friendly with them [7, p414]. When the Japanese troops abandoned Attu Island at the end of August, they moved to Kiska Island with all of the Aleut. Eventually the Aleut were relocated from Kiska Island to Otaru in Hokkaido [7, p413]. However, many of them died in the unfamiliar Japanese climate, and only 24 Aleut were alive at the end of the war [2, p37].
When landing on Attu Island, it estimated to take one week to land supplies (three months' worth of food) from the transport ship "Kinugasa Maru", but the Northern Unit issued a return order to "Kinugasa Maru" on June 10, three days after landing [3, p119]. The reason for this is not written. There were no air raids on Attu Island, only a Catalina flying boat reconnaissance on June 12. The tanker "Nissan Maru," which was supplying fuel (coal) to Attu Island, had requested to call at Kiska Island on the June 10 to replenish aviation fuel to the island. It would lead her to be bombed at Kiska Bay.
4-2 Invasion on Kiska Island
The transport ships "Hakusan Maru" and "Kumagawa Maru" carrying the Kiska invasion troops arrived near Shiraito Bay, north of Kiska Bay, at 2227 on June 7, and the troops started landing. Eventually, 550 men of the Navy Third Special Landing Force, which consisted of 3 companies, an anti-aircraft artillery corps, a surveillance corps (radar staff), and support unit (accounting, medical affairs, and communications), and 750 men of the engineer corps landed [7, p17] [3, p130]. There was a US military meteorological station built on May 18, with 10 observers in the northwest of Kiska Bay. One of the observers was injured when they learned of the approach of the Japanese troops with a machine gun sound. They hurriedly burned the code, but two were taken as the war of prisoners. The remaining eight escaped. However, the wounds of the injured observer worsened, and all but one surrendered to the Japanese troops the next morning [2, p36]. The remaining one also surrendered later.
The occupation of both islands was extensively announced in Japan for the purpose of concealing the defeat of the Battle of Midway. Two fishermen from the Northern Kuril Islands had been also sent to Kiska Island as a fishing group for supplementary food supply. The waters near Kiska Island were blessed with marine products. In the summer, not only were large numbers of cods, flatfish, salmon, and sea urchins caught when fishing, but geese and ducks were also caught when hunting. The fishing group was fishing between air raids and storms, but it is unknown how long they were [7, p409].
A seaplane base was set up on Kiska Island by the special cruiser "Awata Maru". On June 8, Navy Type Zero reconnaissance seaplanes (Jake) were transported by the seaplane tender "Kimikawa Maru", and patrol flight was started by them. On June 9, six Navy Type 97 Large Flying Boat (Mavis) of the East Port Naval Air Corps Detachment and three submarine chasers for defense arrived. Furthermore, on June 15, the seaplanes were reinforced by the seaplane tender "Kamikawa Maru". As a result, the number of seaplanes was follows: Navy Type Zero reconnaissance seaplane was seven; Navy Type Zero Observation Seaplane (Pete) was four; and Navy Type-95 reconnaissance seaplanes (Dave) was two [4, p269].
However, unloading from two transport vessels did not proceed easily. From the June 12, bombing by the US Army Air Corps began, as will be described later. In addition, the pier built on the coast of Kiska Bay for landing using Daihatsu-class landing craft was damaged repeatedly by the waves. In addition, coastal to inland roads had to be opened to carry landing supplies [7, p40].
4-3 US military responses to the Japanese invasions
The United States noticed on June 8 that the weather report on Kiska Island had stopped coming. On June 9, a patrol flying boat found that both islands were occupied by the Japanese troops by discovering the Japanese ships in Kiska Bay and tents built on Attu Island [2, p37]. Chester Nimitz, Commander in Chief of US Pacific Fleet, ordered the Task Force 16 including the aircraft carriers "Enterprise" and "Hornet" to attack the Japanese fleet off Kiska Island on June 8. Task Force 16 headed off Kiska Island. However, Nimitz learned that a radio broadcast from Tokyo was broadcasting that the Japanese had finished occupying Attu and Kiska islands. He stopped the attack on June 11 and recalled the fleet, fearing that Task Force 16 would be ambushed by the Japanese fleet [2, p37]. Since the Japanese Navy changed the code on May 28, the failure to read the Japanese military's plans after the Midway Operation might have also be related to the suspension of the attack.
Until then, the United States had only placed secondary operational value towards the Aleutian Islands. The Japanese may have intended to invade further east. The United States was forced to prepare for defense against the Aleutian Islands and raise the priority of the allocation of war resources. In order to stop the further invasion, the US military first adopted a strategy of exhausting and weakening the Japanese forces by bombing with aircraft and attacking with submarines. Air reconnaissance was frequent because there was little information about the climate and geography of the Aleutian area. Old maps were also pulled out, but those maps only showed the shape of the coastline [10, p73].
Upon learning of the Japanese landing, the US Navy dispatched a seaplane tender "Gillis" to Nazan Bay, Atka Island. Twenty Catalina flying boats were gathered there and intensively bombed on Kiska Island from June 12 to 15, with one pilot flying for 19.5 hours over a 24-hour period for example [2, p42]. Several PBY Catalina flying boats were irreparably damaged, but only one was shot down over Kiska Island.
The Eleventh Air Force hastily gathered B-17 and B-24 bombers at Fort Glenn base from the continental United States, and began bombing Kiska Island on June 12. The runway, which was simply laid with iron plates on a soft swamp, waved like a mattress during the takeoff and landing of heavy bombers. As the first raid, on June 12, three B-24 bombers were launched from Fort Glenn base. Upon arriving at Kiska Island, Japanese ships in the bay were gathered under the umbrella of anti-aircraft fire for defense.
The Japanese shot down a B-24 bomber operated by Captain Todd with anti-aircraft fire [2, p41], and the scene was captured by a Japanese press member on Kiska Island [Imperial Navy Announcement Movie (the last part of it)]. Subsequently, five Catalina flying boats launched from Nazan Bay on Atka Island bombed, and three crew members were killed in anti-aircraft fire. In addition, five B-17 bombers bombed [2, p41], which damaged the starboard front of the destroyer "Hibiki" that was on the alert at the entrance of Kiska Bay. The destroyer "Hibiki" miraculously left no one injured and returned to Kiska Bay towed by the destroyer "Akatsuki" [7, p68].
After that, the bombing of the US military continued as long as the weather allowed. With a round trip of 2500 km from Fort Glenn Air Base to Kiska Island, weather information near Kiska Island was essential for the US air force to carry out long-range bombing. Therefore, almost every morning, a large bomber was dispatched as a meteorological observer around Kiska Island and Attu Island to report the weather conditions [10, p38].
However, the weather conditions west of Attu Island were unknown, and due to variable weather and difficulty of weather forecasts, bombers often turned back on the way even if they sortied. Or, they sometimes bombed by guessing the position of the target by using Mount Kiska (Kiska Fuji), whose head was sticking out of the clouds, as a mark. Fortunately for the Japanese, the US air raids were only successful six times in June due to weather and other factors. In July, the US bombers made 15 sorties, seven of which turned back on the way due to the bad weather. [10, p39]
4-4 Actions of the Japanese military after occupations
On Kiska Island, a coastal fuel depot was bombed and the gasoline continued to burn for several days. The Japanese soldiers on Kiska Island were tense by the relentless air attacks. The soldiers believed that the Navy's flying boats had been bombing. So when they found the large US Army bomber on the ground which was shot down on June 12, they were surprised. They did not expect the large US Army bombers to arrive so soon after landing [7, p64].
These air raids were completely unexpected for the Japanese troops. The seaplanes deployed on Kiska Island had not ability to intercept large bombers, and the number of field anti-aircraft guns laid on the coast in a hurry was small, resulting in insufficient air defense capabilities. Therefore, as will be described later, Navy Type 2 seaplane fighters (Rufe), which had not been originally planned, would be deployed for air defense.
On June 13, the captain of the light cruiser "Kiso" made an opinion to the Northern Unit that on board fighters should be dispatched for interception from the second Task Force over Kiska Island. However, the command of the second Task Force rejected it for confidentiality of the location of fleet [4, p262].
The type 97 Large Flying Boat deployed began patrol flight in mid-June, but during this period the crew had great difficulty in reconnaissance and water landing due to frequent fog. The top altitude of the fog was not high, and mountain peaks on islands often appeared above the fog. Therefore, when landing in the fog, the pilots remembered the topography of the island from the shape of the mountain and plunged into the fog using the same method as the night landing method [13, p204]. However, due to the high latitude, the compass was greatly displaced. Furthermore, after the front passed, the altimeter (barometer) set to zero at the ground pressure at the departure deviated significantly [10, p47].
On June 13, a seaplane reconnaissance aircraft of "Kimikawa Maru" found a seaplane tender and 11 flying boats in Nazan Bay, Atka Island. The Japanese attacked the seaplane tender on June 15 with five Type 97 Large Flying Boat [4, p269]. However, the attack was after the US seaplane tender and the flying boats had left on the night of June 14 due to the exhaustion [2, p42]. There is another view that the seaplane tender had been evacuated by receiving the information on the Japanese attack from the intelligence department in advance [3, p124].
The Japanese flying boats moored in Kiska Bay were exposed to the bombing by large US bombers. Therefore, from June 21 to 22, the large flying boats of the East Port Naval Air Corps Detachment were temporarily removed to Paramushir. The reconnaissance seaplanes also evacuated to Agattu Island except for the seaplanes for observation.
Although they were re-deployed at Kiska Island on July 1, the flying boats of the Yokohama Naval Air Corps, deployed in Tulagi near Guadalcanal Island, were wiped out by the landing of the Allied Forces on August 7. All the large flying boats of the East Port Naval Air Corps were removed to Yokohama on August 14 for replenishment of the Yokohama Naval Air Corps [4, p296]. The reconnaissance seaplane unit left Kiska Island, including the seaplane fighters deployed in July, became the Fifth Air Corps on August 5 [4, p297].
On June 19, the oil tanker "Nissan Maru" was sunk in Kiska Bay by bombing of five B-24 bombers and three B-17 bombers. The military ships and two transport vessels moored in Kiska Bay left Kiska Bay on June 20 with the remaining materials loaded [4, p270]. The US air raids demonstrated their effects, leaving only three submarine chasers and Daihatsu-class landing crafts in Kiska Bay. Two of the submarine chasers were also sunk outside Kiska Bay on July 15 by the attack of the submarine, USS Grunion [4, p325].
Japanese transport ship in Kiska Bay burned by air raid on June 19 (probably "Nissan Maru")
https://www.history.navy.mil/our-collections/photography/numerical-list-of-images/nhhc-series/nh-series/80-G-11000/80-G-11686.html
4-5 Imperial Navy Intercept Operation for the U.S. Task Force
On June 11, the Imperial General Headquarters issued a warning to the Combined Fleet and the Fifth Fleet, as the US Task Force may have headed for Kiska Island from intercepting radio messages [4, p258]. However, as mentioned above, on this day the US Task Force abandoned the attack and turned around.
In preparation for the emergence of the US Task Force, the Northern Unit changed its standby area to 350 km southwest of Attu Island because of the discovery a seaplane tender on Atka Island on June 13 [4, p259]. On the same day, the Combined Fleet Command reinforced the Northern Unit with the aircraft carrier "Zuikaku", destroyers, and others, so the number of aircraft carriers in the Second Task Force became four [4, p260]. A total of nearly 80 Japanese ships had been operating in the area.
The US military sensed the existence of the large Japanese fleets and raised the sense of crisis that the entire Aleutian Islands might be invaded by the Japanese [8, p15]. The US Navy deployed old-fashioned S-class submarines of around 1000 tons in the northern Pacific Ocean to probe the movements of the Japanese fleet, but the navigation was difficult for this class of submarines in the rough seas near the sunken-rock-rich Aleutian Islands. On June 19, the submarine S-27 ran aground near Amchitka Island due to the bad weather. Her crew was rescued after drifting on the life rafts for six days [10, p46].
The commander of the Northern Unit made a plan to dispatched fighters from two aircraft carriers "Zuikaku" and "Zuiho" to over Kiska Island on June 20 to intercept large bombers. However, the plan was postponed to June 21 because of the forecast of bad weather on June 20. However, Combined Fleet Command opposed the operation which divided the air forces of Task Force, so ordered the Northern Unit to return to Ominato on June 20 to prepare for the next operation [4, p262]. Therefore, the dispatch plan of fighters over Kiska Island was not carried out after all. All ships of the Northern Unit, including reinforcements, had returned to Ominato and elsewhere by June 24.
Since the Japanese Navy changed the code at the end of May, the information of the US Military Intelligence Service at the time was confusing. The intelligence agency believed that the Japanese occupation of the western Aleutian Islands could be the beginning of a conquest of the entire North Pacific Ocean [2, p43].
On June 20, the US military intelligence service judged from the radar information that a large Japanese fleet including four aircraft carriers and two battleships was heading north in the Bering Sea toward Nome of Alaska. A large-scale airlift operation of soldiers and weapons was carried out over a two-week period from June 21 using more than 140 transport aircraft to defend Nome where there was no land road [2, p43]. As a result, an army unit of 2000 men was established in Nome in early July. Also, as if to support the invasion of the Japanese troops, the submarine "I-26" fired near Vancouver on June 20, and the submarine "I-25" fired at the US military base on the west coast of Oregon on June 22.
(To be continued)