With the onset of the War in the Pacific, islands that flanked the Japanese South Seas possessions were of great interest to the Imperial General Headquarters (IGHQ) with the Imperial Navy section in the lead. They wanted to secure key locations in order to protect the lateral edge of the Japanese outer-islands. Their main interest was in the Gilbert Ellice Islands, a British Protectorate. Of the northern Gilbert Islands (Code RA) Tarawa (RYB) and Apamama (RHG) were the most appropriate for air facilities.

Fleet Admiral Yamamoto, Commander in Chief of the Combined Fleet, issued Combined Fleet Top Secret Operational Order No. 1 ("Nachi" Document,) on 5 November 1941; it directed the South Seas Force to capture Guam and Wake Islands at the outset of hostilities and to continue the assault on RA. This same order also called for the neutralization of hostile air forces on RJH (Howland Island).

Vice Admiral Shigayoshi Inouye, Commander in Chief of the 4th Fleet, and concurrently Commander of the South Seas Force, prepared to launch operations against Howland Island and the northern Gilberts and the policy was to begin with the assault on the Howland area in an surprise attack, primarily with aircraft and submarines, its objective being to destroy the enemy air forces in the area. Simultaneously, the attacking force was to destroy enemy military installations and to prevent further use of the base in this area. Other units were instructed to carry out mopping-up operations against strategic points in the Gilbert Islands and, at the same time, occupy some of the key points in order to construct air bases to expand the Japanese sphere of air control.

Just before the outbreak of the war, on 16 November 1941, one land-based attack plane of the 24th Air Flotilla secretly reconnoiter the Gilbert Islands by command of Vice Admiral Inouye. The reconnaissance assured the commander that the situation in this area remained unchanged. On the 21st, the disposition order was activated and the South Seas Force repared itself for the operations. With the commencement of hostilities at 0630-hours on 7 December 1941, the air unit began its attacks while other units went into action according to the plan.

The story of the Japanese occupation of the Gilbert Islands falls onto three parts. The first being with the Japanese invasion of Makin Atoll on 10 December 1941 and lasted until the raid by the Marines of the 2d Raider Battalion (Carlson’s Raiders) on 16 August 1942. During this period only Butaritari Island on Makin Atoll was garrisoned. The island was developed as a seaplane base and a lookout station for more developed bases in the Marshall Islands. The second period lasted from 20 August 1942 to March 1943. This phase was characterized by a gradual increase in strength of the garrison, by expansion of the occupied area to include Tarawa and Apamama Atolls and by a change the strategic character of the occupation from that of a lookout post to a fortified station.

These changes were formalized in February 1943 by a reorganization of a command which detached the Gilbert’s from the Marshall Islands (6^th Base Force supported by the 6^th Defense Force) headquarters at Kwajalein Island and established new independent command at Betio, (285 acres in size) Tarawa Atoll. A stable strength figure and a feverish effort to build up fortifications in preparation for an anticipated allied invasion characterized the third period, which lasted from March to the invasion in November.

During the Japanese occupation of the Gilbert Islands were garrisoned by units of the Imperial Navy and it would be well at this point to provide a brief descriptions of the most important types of Naval ground forces that were found in the Central Pacific. These types include Base Forces, (Konkyochitai), Guard Forces (Keibitai), Special Naval Landing Forces (Kaigun Tokubetsu Rikusentai), Defense Forces (Bobitai) and Construction units (Setsueitai). Base Forces were of two types, Base Forces and Special Base Forces (Tokubetsu Konkyochitati), with little difference between the two, except that the Special Base Force were generally smaller. The distinction is important, however, because the new numeral designation might apply to both types. For instance, the 3d Base Force at Palau and the 3d Special Base Force a Tarawa were two entirely unrelated organizations. Outside of Japanese home waters, the Imperial Navy was organized into Fleets directly responsible to the Combined Fleet. While ground formations, especially construction units, hereafter called Encampments Corps, were frequently attached to Fleet Headquarters, they were usually contained in or command of a Base Force. Some Fleet and designated land areas of responsibility. Thus, each Base Force was responsible for land defenses and functions within it area of responsibility, and the Base Force constituted the command echelon directly below the Fleet; Base Forces were commanded by a Vice or a Rear Admiral.

Encampment Corps (EC) [construction units] was composed of both naval personnel and civilian engineer technicians and laborers, and were identified by a numerical designation, i.e., 111^th Encampment Corps. They could be assigned directly to Base Forces. For instance, the 3d Special Base Force in the Gilberts commanded the 111^th EC.

The primary strategic purpose of the Japanese beginning of the Pacific War was the occupation of what they called the “Southern Resources Area, ” the Netherlands East Indies and adjacent regions in order to gain the raw materials they considered necessary to Japan’s economic welfare.

The corollary of this seizure was the maintenance of free lines of communication between Japan and the Southern Resources Area. In order to ensure her hold on these two objectives, Japan hoped to cripple allied surface strength in the Pacific and establish a strong defensive perimeter to protect the homeland and its new economic adjacent to the south. Japan had hoped to make this perimeter strong enough to discourage the Allies will to fight. In accomplishing these purposed the Japanese strategy was through the following stages:

1. The establishment of a perimeter along a line includes the Kuriles, Marshalls, Bismarcks, Timor, Java, Sumatra, Malay and Burma.

2. The consolidation and strengthening of the perimeter.

3. The defense of the perimeter.

4. The implementation of this plan in he Central Pacific and the Bismarcks area was the responsibility of the 4^th Fleet, which before Pearl Harbor commanded naval ground garrisons in the Mandated Islands from its headquarters on Truk.

According to Imperial Navy plans formulated in November 1941 the mission of the 4^th Fleet at the beginning of the war was as follows:

1. Defend the South Sea Islands, patrol, maintain surface communications, capture Wake. At the opportune time attack and destroy enemy advanced bases in the South Pacific area. In cooperation with the Army capture Guam and then the Bismarck area.

2. Search and attack enemy shipping. Make surprise attacks and destroy enemy bases on our perimeter.

The first paragraph outlines the 4^th Fleet part of the first phase of expansion and conquest, and the second states the part of the 4^th Fleet in the subsequent phases of consolidation and defense. The main offensive thrust was to reach southward to the Bismarcks area [Rabaul], while in the east of the line was to be held by the capture of Wake. A minor part of this plan was he seizure of Makin Atoll in the Northern Gilbert for the grater security of the Marshalls.

Makin Atoll, one degree south of the boundary of the Japanese Mandated Islands, offered the advantage of being located about 270 statue miles from the farther to the southeast than Jaluit, the most important seaplane base in the lower Marshalls. The seizure of Makin and it subsequent development into a seaplane base would make it possible to extend air patrols closer to Howland and Baker and Ellice Islands, the overall purpose being to protect the eastern flank of the Japanese perimeter from probable Allied advance along the Ellice-Gilbert chain, a British protectorate. Since Makin Atoll is in the most northerly most of the Gilbert Islands, it is the easiest to supply by transport from the Marshalls.

The 4^th Fleet, which exercised command over all Japanese naval ground forces stationed in the mandates, had no large surface units. The command had four older cruisers, the Kashima, Tenryou, Zxatsuta and the Yubari. A few destroyers, a large number of transports, gunboats, minelayers, minesweepers and submarine chasers. The warships were assigned to the 4^th Fleet headquarters at Truk, while most of the smaller craft and ground forces were commanded by four Base Force headquarters. When necessary, large surface units from other fleets were attached to the 4^th Fleet. For instance, November 1941 plans called for the carriers of Carrier Division 1 to support the 4^th Fleet operations in the Bismarcks area after the conclusion of the Pearl Harbor operation.

The 6^th Base Force, the Japanese nerve center in the Marshalls, participated in the Wake Island Operation (U Sakusen) and the Gilbert’s Operation (Gi Sakusen), provided all the ground forces and most of the surface forces for the latter. The Gilbert’s Operation in the initial phase was under the command of the Yokohama Naval Flying Corps (Capt. Shigetoshi Miyazaki IJNAF). The invasion force was to stage through Jaluit, the southernmost of the Japanese bases in the Marshalls at this time.

The 51^st Guard Unit on Jaluit organized a Gilbert Island Special Land Force ( Ratokubetsu Rikusentai) by detaching one company (Rilujo Butai) and on 3 December this force was placed under the Air Force command. The 51^st Guard Force remained responsible for supply for the landing forces and was to cooperate with the Imperial Navy Air Force in anti-air and anti-submarine patrol, for which they used small naval vessels regularly under its command. On 3 December, the auxiliary patrol vessel Nagata Maru (a converted gunboat) was detached from the Jaluit command and attached to the Air Force. The minelayer, the Okinoshima (4,400 tons) and the auxiliary minelayer Teyo Maru No. 2 (6,843 tons) was dispatched from the 4^th Fleet and arrived on Jaluit on 3 December.

With the outbreak of war, at 0630 hours on 8 December 1941 (7 December in Hawaii) and units went into action according to the plan. At 1330, supporting group composed of the 19^th Minelayer Division Okinoshima and Tenyo Maru), the 2d Section, Asanagi and Yuragi of the 29^th Destroyer Division and the vessels of 8^th Gunboat Division, the Nagata Maru left Jaluit Island to capture the Gilbert Islands. The Asanagi and the Yunagi reached Tarawa Atoll at 2400 on 9 December and immedadially landed a combined landing force (ships complement) of approximately 200 men without meting resistance. By 0600, the next day the landing force had completed mopping up operations. Then, the force headed for Makin anchorage to cooperate in the construction of a seaplane base. They departed Makin on the 13^th, and, with a supporting group reached Roi (within the Kwajalein Atoll) the following day.

Meanwhile, the Okinoshima and Tenyo Maru, with one company of the 51^st Guard Force (Rilujo Butai) on board, reached Makin Island before dawn on the 10^th. Both the Tenyo Maru and Okinoshima debarked their land combat personnel at 0219, and completed cleaning up the island by 0800. Two hours later, the Nagata Maru arrived and unloaded the seaplane construction materials and within two days the flying boat facility was completed. On the 11^th, the Okinoshima departed to disembark other land combat units on Little Makin, six miles away. On the 24^th, she left for Abaiang Island. After neutralizing the islands, the forces were taken aboard the Okinoshima and returned to the Roi anchorage. In the Gi Sakusen nine prisoners were taken. All the troops were withdrawn except for Makin, where the detachment of the 51^st Guard Force and the base personnel of the Yokohama Naval Flying Corps were assigned to guard the seaplane base, as several Kawanishi Type 97 flying boats used the facility to patrol the area.

On 10 April 1942, the 51^st Guard Force detachment on Makin was reorganized as the 62d Guard Force. Its designation was known as the 62d Guard Force, Makin Dispatched Landing Force now commanded by Warrant Officer Kanemitsu. Its main force was on Kawjalein with detachments on Jaluit and Maloelap. Makin remained as a lookout and air station. By August, the troop strength on Makin dwindled to 44. The situation remained immobile until mid-August 1942.

At 0315 on 17 August, A and B Companies of the 2d Marine Raider Battalion consisting of about 200 Marines, (Carlson’s Raiders) landed on the south side of Butaritari Island from two submarines, opposite of the principal settlement. The Raiders were on a destroying rampage. At 0905, the garrison radioed the 6^th Base Force, “All men are dying serenely in battle.” Warrant Officer Kanemitsu and 43 of his man died. Beginning in late on the 18^th the Raiders made their difficult way back to the subs however; nine Marines being out of touch and were left behind.

The reaction to the Carlson’s raid involved not just the replacement of the Makin militia, but the garrisoning and fortifications of the Gilbert & Ellice Islands colony on a hitherto unprecedented scale. In the following month, Nauru, Ocean, Tarawa and Apamama were invaded and garrisoned, and operations were conducted to clear the Gilbert’s of any and all nationals and Allied personnel. At first, the 4^th Fleet ordered small elements of the 5^th Special Base Force (Saipan) and 4^th Base Forces (Truk) were sent into the islands to be brought under Japanese control. Gradually these forces were replaced or absorbed by larger units destined to become permanent garrison forces. When it was determined that no major enemy force was on Makin Island, the Japanese moved quickly. They organized the 6th Base Force Combined Landing Force led by Lieutenant Morimoto and created in company strength from elements of the 61^st. (Kwajalein) and ^the 62d Guard Force (Jaluit) for immediate deployment. On the 20^th, 35 men were detached from the 62d Guard Unit and flown from Emidj, Jaluit to Makin in two flying boats one from the 19^th Air Unit on Kwajalein and one from the 24^th Air Group on Truk. The balance of the landing force followed by water transportation leaving on the 19th includes the minelayer Tokiwa, three other sub-chasers and the Daido Maru. The Daido Maru reached Makin at 1015 on the 21^st. The next day, mopping up operation began including the newly arrived joined the 35 that had been flown in earlier and had taken nine Marine prisoners. They captured 5 rubber boats, 15 machine guns, 5 rifles, 24 automatic pistols and 350 rounds of ammunition.

Now began a series of troop movements from all directions to converge on the British Island possessions bordering the Marshall Islands. A landing party was formed at Truk by detaching one company from the 41^st Guard Force. This formation with its equipment was loaded on board the Kooi Maru which left Truk anchorage on he 26^th and arrived on Ocean Island on the 30^th. On the 29^th, a landing party composed of one company (Ariaka Butai) of the 43d Guard Force (Palau) assumed the duties of the occupation of Nauru. On the 27^th, another company was detached from he 62d Guard Force commenced the occupation of Ocean Island. Three days later still another company from the 41st Guard Force joined this force. A Company was detached from the 5^th Special Base Force on Saipan and departed the station on the 28^th aboard the Shotoku Maru and arrived Makin on the 30^th. There it remained pending the arrival of a special landing unit from Japan.

Besides there movement into new territory, Mille, Marshall Islands, hereto merely a lookout post, was occupied by the Yokosuka 3d Special Naval Landing Force SNLF (844 men) which had been transferred from the southwest. This formation was placed under the 4^th Fleet on 20 August, arriving at Truk from Rabaul on the 25^th and reached Mille on the 30^th.

These moves were followed by the Apamama Invasion Operation that lasted from 31 August to 4 September. This was accomplished by the usual anti-submarine and anti-air-protection afforded by small naval vessels and aircraft of the 19^th Air Group. It will be recalled that the 6^th Base Force Combined Landing Force which had landed on Makin after the Carlson’s raid was composed of elements of the 62nd and 62d Guard Force. Elements taken from the 62d were now divided into two sections, called ‘A’ Detachment and ‘B’ Detachment. Detachment ‘A,’ commanded by Lieutenant Taniura and known as the Taniura’ Detachment, boarded the Daido Maru at Makin on the 31^st, and arrived on Apamama on 2 September, approaching through the South Passage. The Taniura Butai debarked and proceeded to conduct mopping up operations. Also on the 31^st, B Detachment, under Warrant Officer Otsuka, also left Makin for Apamama aboard the Katori Maru and reached the island through the West Passage arriving on the 2d. Otsuka Butai began moping up operations in a southerly direction. Both formations in cooperation destroyed enemy communications equipment and by 6 September the island was declared secure.

The largest and most significant troop movement that incurred directly after the Makin raid was the dispatching of the Yokosuka 6^th Special Naval Landing Force (Comdr. Keisuke Matsuo) from Japan to the Gilbert’s. This was the first unit of considerable strength to arrive in the area and its strength at the time was 52 officers, 1,440 enlisted sailors and 18 civilians. The Yokosuka 6^th as organized at Yokosuka on 15 August 1942, two days before the raid on Makin. The following week was spent in preparation from departure from Japan, which was completed on he 23d. The next day, the Yokosuka 6^th left Yokosuka on two transports (Hitachi Maru and the Katori Maru) bound for Jaluit. On the 25^th, it was assigned to the 6^th Base Force and given the mission of defending Tarawa. On 5 September the SNLF arrived at Emidj, Jaluit Atoll, where it disembarked to await transfer to the Gilberts. At Emidj, it was divided into two parts; one called the Tarawa Main Force, and the other the Makin Dispatched Force. The Makin formation was transported in two stages, on segment departed on board the Ikuta Maru on 11 September and the other leaving the next day aboard Katori Maru. Both ships arrived on Makin on the 13th and 14^th. The Makin Dispatched Force, on arrival assumed responsibility for the defense of Makin Island and the units, which had arrived previously, were released for duty elsewhere. These forces were the company detached from the 5^th Special Base Force and some of the troops from the 61^st Guard Force. The 5^th Special Base Force company boarded the Katori Maru and departed Makin on the 15^th and arrived at Nauru two days later and began garrison duties.

The Tarawa Main Force left Emidj on 13 September and arrived at Betio, Tarawa on the 15^th. On the same day, 76 men were detached and formed the Apamama Detachment and reached the island on the 16^th. The one company detached from the 62d Guard Force, which had landed first on Tarawa and then on Apamama, now was transferred to Ocean Island. The major section of the Tarawa Main Body started to set-up defenses for the island, except the 2d Platoon, 3d Company, which was assigned to the Gilbert Islands moping-up operations.

Since the beginning of the war a number of New Zealand coast watchers (and a few Australians) had remained in various islands of the central and southern Gilberts, observing Japanese air and surface movements. The Gilbert area mopping-up operations were designed to destroy those sources of allied intelligence. The first step was the formation of a small surface force, which patrolled the waters between the Gilbert and Ellice Islands beginning on 21 September. The operation itself lasted from 24 September to 6 October. The 2d Platoon, 2d Company Yokosuka 6^th SNLF was divided into two parts identified as the first and second mopping-up parties.

On Betio, the 1^st Mopping-up party of 24 sailors boarded the Katori Maru on 24 September and accompanied by the destroyer Yuzuki, 4^th Fleet. Both vessels left the anchorage the same day and arrived at Beru Atoll on the 26^th. The landing party went ashore accompanied by 25 sailors from the Yuzuki and occupied one edge of the island, where they destroyed a wireless station and then returned to their ships. On the following day, the Katori Maru sailed to Tamana Atoll 60 miles south of Tarawa and landed at Bakaka Village. This was the southern most point reached in these operations and the limit of their land operations. Here, they destroyed communication equipment and captured two New Zealand soldiers and one wireless operator. Then they turned north and landed at Tabiteuea, the largest atoll in the Gilbert Group, reaching there on the 26^th. In checking they found no communication equipment. The only Europeans they found were two French missionaries and on 30 September they returned to Tarawa.

The 2d Mopping-up party aboard the Daido Maru left Betio on 25 September, and reached Maiana Atoll some 20 miles from Tarawa. Some communication equptments was confiscated. Going further south they landed on Nonouti Atoll in the central Gilberts and captured communication equipment. On the 28^th, they turning back north and made a landed on Kurita Atoll that netted more wireless equipment and three prisoners. On the 30^th, they returned to Betio. On 6 October the Gilbert Islands were declared completely clear of enemy personnel.

The period following the Marine raid on Makin was characterized not only by the seizure of new island bases and increased garrison strength but by energetic efforts towards the construction of fortifications as well. During September gun mounts were completed at various Marshall Islands bases, and defensive installations were begun in the Gilberts.

The strength in the Gilbert Islands jumped from 44 men to over 1,500 plus four companies on Nauru and Ocean Islands. Before the raid, Makin had been within the command area of the 62d Guard Force. After the raid three new command areas were created in the Gilberts on the same level as the 62d Guard Force, and directly responsible to Kwajalein. The troop movements in August and September were only the beginning and the Japanese continued to build up strength in the Gilberts and the entire 4^th Fleet area (Marshalls, Carolines and Marianas) as well.

The end of 1942 and the beginning of 1943 was a period of characterized by a great increase in naval ground force in the 4^th Fleet area. By October the sailors of the Yokosuka 6^th SNLF had already began constructing 8-mm and 14-cm gun positions on Betio, but the fortification plans had exceeded the capabilities of these sailors and steps were taken to dispatch a construction unit to the Gilbert area. On 20 October 1942, the 111^th Encampment Corps was activated at Kure, Japan. Preparations for departure, including accumulating supplies, uniforms, weapons, construction material and ordnance stores, were made both at Kure and Tokyo. By 6 November, the unit was brought up to strength and some attempts were made to provide the assemblage with some military training. On 10 December, the 111^th EC departed Kure docks for Kwajalein, where materials for two 20-mm turret guns were brought aboard. On 26 December, the formation arrived on Betio, and immediately began the construction of temporary defenses. Most of the 111^th remained on Betio, but detachments were parceled out to Makin, Nauru and Ocean Island. Strength figure for 16 January 1943 shows the 111^th with 153 military personnel (security), 34 technicians and 1580 laborers for a total of 1,767.

On 15 February 1943, the Gilbert Islands, Nauru and Ocean Islands were removed from the command of the 6^th Base Force and placed under a newly activated 3d Special Base Force with headquarters on Betio, Tarawa. This force came into being by simply deactivated the Yokosuka 6^th SNLF and renamed the 3d Special Base Force. For a brief period, Comdr. Keiuke Matsuo, the commander of the Yosokuka 6^th ,was is command of the force. The next day, Rear Adm. Saichiro Tomonari who had recently commanded the 5^th Special Base Force on Saipan took command of the new unit.  However, the one basic change was the status of Nauru and Ocean Islands, which now came under the command of the 3d Special Base Force on Betio. The chain of command ran through Nauru, which in turn commanded Ocean Island. Commander Matsuo distraught over the loss of his command took his life n 2 May 1943.

Also on the 15^th, the four dispatched landing force identities on Nauru and Ocean Island were deactivated and formed the 67^th Guard Force, with headquarters on Nauru and responsible to the 3d Special Base Force on Betio. The 43d Dispatched Landing Force and the 5^th Special Base Force Dispatched Landing Force became the 67^th Guard Force Nauru Main Force. The 62d Guard Force Dispatched Landing Force and the 41^st Guard Force Dispatched Landing Force became the 67^th Guard Force, Ocean Island Dispatched Force. In the beginning of 1942, the Japanese had nothing more than a lookout station in the Gilberts, which was subordinate to a Guard Force command which was in turn responsible to a Base Force on Kwajalein. Now, in February 1943, the Japanese forces in the Gilberts were constituted as a Base Force command equal to that of the 6^th Base Force on Kwajalein.

They lost no time in beginning work on fortifications once they committed sizeable garrisons to the Gilberts, Nauru and Ocean. The Makin garrison completed work on temporary positions by the end of September. From 1 to 6 October the garrison was occupied with the installation of 8-mm gun positions and within the next month three others were set up. They installed flat trajectory weapon positions from 7 to 9 October and various degrees of barbed wire entanglements from the 15^th until the end of October. By 10 December, they had completed positions for 7.7-mm machine-guns. January and February the garrison continued to construct fortifications and extended training. On 19 January, 5 planes of the 802d Air Detachment arrived on the island.  On 1 November it was redesignated as the 14^th Naval Air Group. Later on the 952d Naval Air Group (Lt. Comdr. Kaoru Ishihara) supported this unit.

Meanwhile, the Tarawa garrison was a bit slower in getting started. Troops transfers occupied them, command changes, mopping up operations. On 29 October, the 111^th Encampment Corps began construction of the 8-cm flat trajectory gun positions on the eastern tip on Betio. On 15 November a party left Betio bound for Tabikeriki, Beru Atoll on a reconnaissance mission and finding no Europeans they returned two-days later.

The first week in December, 13-mm machine guns positions on Betio were completed. On 26 December, the 111^th Encampment Corps immediately went to work on various defense installations, including laying plans for the installation of 4 14-cm guns, 4 12.7-cm twin mount dual-purpose guns, 2 20-cm guns, ammo magazines, a receiving station an a C/P for air units destined for Tarawa.

Ten days later three B-17s of the VII Air Force raided Betio and were met with anti-aircraft fire and no damage was inflicted or received.

Historian Admiral Morrison reported “At the corners of the island and at various other points along the shore 14 coast defense guns ranging from 5.5 inch to 8 inch. Along and inside the beach were 25 field guns, 37-mm and 75-mm in covered emplacements, mostly in pillboxes well protected from shrapnel blasts by thick covering of logs and sand reinforced by armor plate or concrete caps, and immune to direct hits from all but the largest guns; (b) a number of 13-mm to 5.1-inch antiaircraft guns.”

The Sasebo 7^th SNLF was organized at Tateyama, Japan on 1 February 1943 and was engaged in training and preparation for departure until the 19^th. The next day they were attached to the Southeastern Area Fleet at Rabaul, which indicates the formation, was to proceed to the Southeast. The SNLF arrived at Yokosuka on the 20^th and boarded two transports bound for Truk reaching there on 8 March. Here, the unit was detached from the Southeastern Area Fleet and attached to the 4^th Fleet and departed Truk on 12 March for Betio, Tarawa and arrived there on the 17^th. On arrival its mission was to defend Tarawa and placed under the command of the 3d Special Base Force with strength of 1,669.

The 3d Special Base Force, including the personnel of the Yokosuka 6^th SNLF, had to make changes at Nauru, one of the new targets for the Allied Air Force. On 27 March, a force of 7 offices and 301 enlisted sailors was detached from the Tarawa main force and left Betio aboard the Ikuta Maru bound for Nauru and reached there three days later. At Nauru, it came under the command of the 67^th Guard Force.

On 4 March, a detachment of 76 men from the 111^th Encampment Corps departed Betio for Nauru on board the Ikuta Maru and arrived there on the 7^th In mid April the detachment was reinforced with 140 more men, and all were employed on construction details on Nauru including building an air strip. The 20^th, 36 men were detached from the Nauru Detachment and sent to Ocean Island, and this number was augmented by 17 more on 30 April.

On 7 May, the 4^th Fleet Construction Department unit arrived on Betio from Truk. On arrival, it was designated, Tarawa Detachment, 4^th Construction Department. This unit was drawn from the labor pool 17, 338 on Truk, mostly Koreans. Eventually, sections of the department were parceled out with sub-detachments on Makin 276, Nauru 210, and Ocean Island 40.

In mid-April, orders were issued dispatching the 1^st South Sea Detachment, "Nanyo Daiichi Shitai," with a strength of 1,200 to Tarawa where it was to replace the Sasebo 7^th Special Naval Landing Force as it was planed that unit would garrison Mille on the Marshalls. The 1^st South Sea Detachment was redesignated from the 122d Infantry Regiment where it operated in the Philippines as part of the 65^th Infantry Brigade.  The unit sailed for Tarawa in Bangkok Maru, but the transport was torpedoed and sunk off Jaluit on the 20th by the USS Pollack, SS 180. Some 400 troops were lost in the sinking with the remainder was taken to Jaluit. This caused the transfer to be abandoned, and the Sasebo 7^th would remain on Tarawa.

The above installations include signal posts, magazines, range finders, searchlights, ready rooms, barracks, signal stations, revetments and earthworks.

After the spring of 1943, men and material were shipped to the Gilbert Islands to strengthen their defenses. However, enemy submarine activities as well as the shortage in Japanese shipping created two problems: postponing, enemy units in the southern Ellice Islands, and supplies and arms for defense and fortifications, only arrived in small quantities. These were the circumstances when Rear Admiral Keiji Shibasaki reached Tarawa 20 July 1943.      

Admiral Shibasaki relieved Admiral Saichiro who returned to Japan. Admiral Shibasaki had a varied background. In November 1942, he was Chief of Staff of the Shanghai Special Naval Landing Force with an additional duty as the Chief of Staff, Shanghai Area Base Force. Following that he was ordered back to Japan and on 23 April 1943 he was assigned as the Commander of the Kure Defense Squadron. On 1 May he was promoted to Rear Admiral and on 9 July, was attached to Headquarters, 4^th Fleet at Truk. Ten day later he was assigned as the Commander of the 38^th Special Base Force and on 19^th he was assigned as the commander of the 3d Special Base Force on Betio, Tarawa.

As soon as Rear Admiral Shibasaki had taken his post he introduced a new program by enforcing military discipline and training. Another hallmark of his leadership, his bluejackets underwent rigid training from dawn to dusk. As a result of this intense training, which was conducted for a period of four months from the day of Admiral’s arrival to the day of the enemy's attack, their strength was improved tremendously with the resulting psychological lift to the men.

Meanwhile, the 4^th Fleet assigned Motor Torpedo Boat # 123, and the Takunan Maru to the 3d Special Base Force for patrolling.

On 10 June, the Yokosuka 2d SNLF led by Capt. Hisayuka Soeda was included in the 3d Special Base Force and advanced to Nauru on 25 June to assist the 67^th Guard Force in the defense of the island and became known as the 3d Special Base Force, Nauru Detachment.

On 2 October 1942, a Marine and Naval Task Force from Samoa landed on Funafuti, Ellice Islands. It consisting of the Marine Corps 26th and 27th Provisional Companies X and Y, the 4th Detachment, 2d Naval Construction Battalion and Naval Administrative Group No. 3 plus the Advance Marine Base Depot formed the post. A few days later Motor Torpedo Squadron 3 (2) began operating from the island as well as a detachment of VOS float planes from VS-1-D14. The island was reinforced with the arrival of the 5th Marine Defense Battalion less detachments “A”and“B.” The Japanese were unaware that the Americans were positioned on their southern flank until sighted by a passing flying boat in March 1943. By that time United States forces were fully entrenched in the Ellice Islands.

The United States occupied Baker Island on 10 September 1943 with an engineer element of the VII Air Force. To further the penetration in the Central Pacific they immediately established air bases and stationed land and air force components under the 11th Bombardment Group, VII Air Force bases at Nanomea, in the Ellice Islands the 7th Marine Defense Battalion, Nukufetau 2d Airdrome Battalion Marine. Then they proceeded with air strikes against Makin, Tarawa, Nauru and Ocean Islands.

On 1 September a carrier strike force USS Yorktown CV 10, USS Essex CV 9 and USS Independence CV 22 attacked Japanese held Marcus Island. On the 19th another task force built around the USS Lexington CV 16, USS Princeton CVL 23 and the USS Belleau Woods CLV 24 attacked Tarawa and Nauru.

The Combined Fleet, in accordance with a pre-arranged plan of operations, had been seeking an opportunity to contact the enemy fleet that it had expected would appear in the Central Pacific sector. In mid-September, the Combined Fleet calculated that there was a strong possibility that the United States carrier striking force would attack the Gilbert and Marshall Islands area. Therefore, it dispatched its carrier force to the latter area to await the expected enemy. On the 18^th, the Combined Fleet issued orders on interception and security dispositions and assembled the air units assigned to the flotilla commanded by Rear Admiral Shunichi Kira. The next day, a United States carrier strike force raided the cordon of Japanese bases on Makin, Apamama, Nauru and Tarawa. For some reason the Japanese air units from the Marshall Islands failed to make contact.

On 6 October, another carrier task force attacked Wake Island and subjected the island to an air raid and naval bombardment. The play for Wake was to confuse the Japanese into assuming that the island was to be invaded. However, in the grand scheme of the Allied Central Pacific drive Wake Island was strategically unimportant. On the 7^th, the Commander in Chief of the Combined Fleet Admiral Mineichi Koga issued an alert order designating 11 October as X day under measure 1 of the “HEI” Operation, with orders for the following dispositions to intercept the enemy:  One land-attack plane unit, about 18 aircraft, of the Southeast Area Force, Rabaul based, will be placed under the command of the Inner South Sea Force and all operational land-based attack planes of the Northeast Area Force will advance to Marcus Island.

The 7th Cruiser Division and the 10th and 17th Destroyer Divisions, assigned to the Inner South Sea Force at Truk, and currently under the operational command of the Southeast Area Force, will return to their original command.

In accordance with an established plan, the Commander of Inner South Seas Area Force issued numerous orders for the defense of the Gilbert and Marshall Islands as well as Nauru and Ocean. With regard to the air operations, new air tactics were perfected. The Japanese felt that these tactics would be so effective that their confidence in being able to cope with the enemy increased. The essentials of the air tactics were as follows:

1. Patrol of operational waters was, to be the responsibility of the 22d Air Flotilla and the attack on the invading enemy was to be made by 36 land-attack planes detached from the Southeast Area Force, and land attack planes and fighters of the 22d Air Flotilla.
2. Until the enemy attacked, the strength of the 22d Air Flotilla was to be dispersed as far as possible, while the strength maintained at advance air bases would be limited to the strength needed for patrolling.
3. As soon as the enemy's intention to attack became known, the air components were to concentrate on developing their striking power to the fullest.
4. Until the enemy attacked, vigilant air patrols were to be maintained and the remaining air units were to train diligently to increase their combat efficiency.

The Japanese Air Force attacked the enemy bases at Funafuti and Nanumea in the Ellice Islands on 11 and 13 November and the enemy struck back, subjecting Tarawa daily to bombing raids from heavy land-based planes from the l4th through the 17^th. The next morning, the VII Air Force bombers dropped 115 tons of bombs on Betio.

During this time the Japanese arrived at an estimate of the approximate size of the enemy air bases on the Ellice Islands as well as their aggressive intention toward the Gilbert and Marshall Islands. Meanwhile, Admiral Chester Nimitz, Commander in Chief. US Pacific Fleet, broadcast, to the effect, that the US Force would shortly begin a campaign to capture the Gilbert and Marshall Islands. Against this boast, the Japanese enforced diligent patrols employment of submarines and inactivated the KO Submarine Group. It then assigned the I-19 to observe the Hawaii area, the I-35 to observe the Espiritu Santo New Hebrides Islands area by way of Canton and Funafuti, and ordered the I-169 and 1-175 to return to the base at Truk. The RO-37 was ordered to watch the area around the Gilbert Islands.

On the 18^th, the Americans subjected Betio Atoll to four strafing and bombing attacks with fighters and bombers, totaling 910 sorties flown from the carrier striking task force. Again on 19^th, the Americans flew 170 sorties against the island with carrier planes and 30 B-17s and 24s large land-based planes. These attacks destroyed the runway on Betio Island and caused casualties, destroyed defense installations and the fighting power of the garrison was greatly reduced. This marked the beginning of the invasion of the Gilbert Islands.

On 19 November, 0630 hours, two enemy carrier striking task groups TGs 50.2 and 50.3 were discovered the 22d Air Flotilla 100 miles-south and southwest of Tarawa. At approximately 1100 hours 19 Imperial land-attack planes hammered the task force. They met with fierce resistance and lost 10 of their aircraft. The Commander in Chief of the Combined Fleet ordered the air unit of the Japanese carrier force to advance to the Marshall Islands to attack the enemy carrier striking task force in concert with the air unit of the 22d Air Flotilla, At the same time, the air unit of the 22d Air Flotilla was ordered to attack enemy transports. The enemy started landing on Tarawa and Makin on 20 November. The commander of the Japanese Naval Air Force launched an assault with 16 land-attack planes upon enemy transports near Tarawa, but, due to the poor coordination between the search and attack units, only piecemeal attacks were conducted against the enemy carrier force arriving in the Tarawa waters. Thus, the Japanese plan to destroy the enemy transports was nullified, and nine of the sixteen land-attack planes failed to return to their base.

When the enemy carrier striking task force attacked the Gilbert Islands, the Commander of the-Submarine Force decided to concentrate all operational submarines in the waters of this area, and reactivated the KO Submarine Group comprising the L19, I-169, I-175, I-55, I-21, and R0 35 and designated the Commander of the 2d Submarine Division aboard the I-19 as the commander of this group. This group was directed to rush to the scene of battle and assume the pre-assigned positions. On the 19th,the Commander of the Submarine Force reinforced the KO Submarine Group with three more submarines, the 1-39, I-40 and I-174. These submarines cleared Truk about the 20th.

A Battleship, three cruisers and six destroyers, were sighted some 18,000 meters off Tarawa at an azimuth reading of 320 degrees. As the enemy naval ships commenced bombardment, the Japanese land batteries returned fire. However, the shelling prior to this landing silenced the heavy guns on the land, destroyed almost all the ground installations and killed nearly half the strength on the island. On being informed of the Task Force being at Betio’s doorstep, the Commander of the Inner South Seas Force ordered his air units to contact and attack the enemy task force which had launched the air attacks on Tarawa and Nauru. The afternoon of the same day orders were issued to units under his tactical command alerting them for "HEI" Operations No. 3, but the air units were not able to counterattack effectively.

Admiral Koga, in the meantime, ordered the operational air force of the northeast Pacific Area Force and the land attack plane units of the Southwest Area Force to rush to the Truk area, simultaneously posting the Submarine Force at pre-arranged intercepting positions. During the night of 20 November, Admiral Koga gave orders to all the troops under his tactical command to prepare for "HEI" Operations No. 3.

1. The enemy situation was made clear. The land attack plane units of the Northeast Area Fleet, which had advanced to Truk, and all available air and submarine forces in the Marshall Islands would attack and ‘whittle down’ the enemy fleet.

2. Air units of the carrier divisions would advance to the Marshalls area and take part in the above assault.

3. The main force and the advance force would leave Turk to participate in the decisive battle at the proper time.

4. An element of the surface force would transport Army KO Detachment (2300 soldiers from the 52d Infantry Division) located at Ponape to the Marshall Islands and when the opportunity arrived would make a forced landing at points in the Gilbert’s area where the Americans landed, and destroy their ground force. The detachment was built around the Col. Manjiro Yamanaka IJA, the Commander of the 107th Infantry Regiment (52d Infantry Division) supported by elements of the 52d Artillery Group, 16th Mountain Artillery Regiment, the 52d Engineers and the Medical Unit from the 52d Infantry Division.

On 20 November, 18,600 Marines from the 2d Marine Division and the V Amphibious Corps spearheaded by the 2d Marine Regiment reached the Betio’s breastwork at 0910. The first landing was attempted on both sides of the main pier on the northern shore of Betio Island and near the northwestern tip of the island. Some 200 amphibious tanks and landing craft were employed, but about two-thirds were destroyed in the course of landing, while the others succeeded in reaching the shore. The Japanese forces closed in on the enemy from three directions: south, east, and west and pressed the enemies near the pier where fierce close quarters combat ensued.

As soon as the enemy started landing in the Gilbert area, the Commander in Chief, of the Combined Fleet reacted and ordered the Army KO Detachment as reinforcements to the Gilbert area. He ordered the cruisers Naka, Isuzu, Nagara and two destroyers, a11 of which belonged to the Inner South Seas Force, to transport the KO Detachment to Kwajalein at once. The Advance Force was to act as escort and prepare for a counter landing under the command of the Commander of the 14th Cruiser Division which had cleared Truk on the 21st, reached Ponape on the 22d, left Ponape on the 23d, and reached Kwajalein on the 25th.

At noon, on D-day, the batteries of the USS Maryland BB 46 and the USS Santa Fe CL 60 scored a direct hit on the block house command center shelter and killed Admiral Shibasaki and most of his staff reportedly containing about 300 sea-infantrymen. Although the command center was destroyed and effective command liaison ceased, the morale of the garrison showed no decline. Each unit carried out offensive action according to prearranged plans and held the enemy.

On the morning of the 21^st, the Marines landed their reserves, in addition to the units that had previously landed at the northwestern tip of the island and occupied the whole of the western shore. In addition, four destroyers and five transports entered the lagoon, while one battleship and one cruiser stood off during the landing of men and supplies.

It was apparent on the 20^th that the enemy's main target was Tarawa and the commander of the Submarine Force ordered the I-175 to stand off Makin and the rest of the group, except the I-169, off Tarawa. The situation in the I-175 Gilbert area became hopeless and it was impossible for the Japanese to send land troop reinforcements to this area.

Meanwhile, the Japanese garrisons on Tarawa and Makin had fiercely resisted the enemy since their landing. Particularly on Tarawa, the Japanese troops at one time pressed the enemy back to the narrow beaches and took a heavy toll of their forces, but finally were compelled to retreat.  

At 1330 on the 22d, communications with Tarawa ceased completely. Soon after, the Japanese positions on the island were evidently overrun one after the other by enemy tanks. On the 23d, the island fell. Consequently, on the 24^th, the Commander in Chief, Combined Fleet, advanced one battalion of the Amy unit located at Ponape to Yusaie to garrison the island and he canceled the landing of the KO Detachment that had advanced to the Kwajalein Atoll.

Thus, the plan to seize the tactical opportunity to subject the Americans to the coordinated attack of air, sea, and land forces in the Gilbert area was never realized. After the fall of the Gilberts, the Combined Fleet planned to contact and destroy the enemy fleet with air power reinforced from the Northwest Area Force by concentrating in the Marshall Islands area.

At 1200 24 November 1943, the Marines witnessed a formal flag raising ceremony. The war for Betio was over.