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Chapter 15: The Japanese Reinforce Biak

Biak and Japanese Naval Plans

As the Biak operation began, both ALAMO Force and General Headquarters, Southwest Pacific Area, estimated that the principal Japanese reaction to the landing of the Task Force would be aerial in nature. Since it was believed that the Japanese were committed to a policy of conserving their remaining naval strength, it was considered improbable that they would risk major fleet elements to counterattack at Biak or reinforce this island in the face of Allied land-based aircraft which were either at fields within range of Biak or which were expected soon to be flying from strips captured there. Attempts by the Japanese to reinforce Biak by barge movements from more westerly bases were also considered improbable. Such movements would have to be made at the mercy of Allied Naval Force PT boats operating from Mios Woendi or Allied aircraft from the Biak fields. Finally, it was considered improbable that the enemy would choose to weaken his garrisons at Noemfoor Island and Manokwari by sending reinforcements from those bases to Biak.1

These estimates of enemy intentions were incorrect. The determined defense by the Biak Detachment prevented the Allies from using the Biak airfields as soon as had been expected. Therefore, all aerial efforts to locate and destroy Japanese seaborne reinforcement movements had to be made from Wakde Island or Hollandia. Moreover, not only had the Japanese made ambitious plans to reinforce Biak, but they were also willing to risk important naval air and surface units to make sure that the reinforcements reached their destination.

Japanese Naval Planning, Early 1944

The 9 May withdrawal of Japan’s southeastern strategic main line of resistance to the line Sorong–Halmahera meant, in essence, that no reinforcements were to be sent to Biak and Manokwari, now relegated to the status of strategic outposts. But the landing of the HURRICANE Task Force on 27 May engendered a change in attitude at Imperial General Headquarters concerning the importance of Biak. Prior to this time, the defense of Biak had been principally a responsibility of the Japanese Army, but now the Navy Section, Imperial General Headquarters, began to take a decisive hand in the planning for operations in the western New Guinea area.2

Allied carrier operations against the Palaus and Sarmi in early 1944, coupled with continued Allied advances along the

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New Guinea coast and the concomitant weakening of Japanese Army air strength in western New Guinea, prompted the Japanese Navy to reinvestigate Biak’s defensive potentialities. The Navy decided to strengthen its rather meager forces on Biak and, apparently early in April, sent airdrome construction units, a few antiaircraft troops, and some supply units to the island. In May the 19th Naval Guard Unit elements arrived there.3 One of the airfields on Biak apparently was to have been used solely by the Japanese Naval Air Service. Be that as it may, the Navy’s interest in Biak during April was insignificant compared with that aroused by the Allied landings on the island.

The background of this interest lay as far distant in time as the disastrous defeats suffered by the Japanese Navy in mid-1942 and in plans formulated by Imperial General Headquarters during the fall of 1943 to develop bases in the western New Guinea–eastern Indies area from which to launch a major counteroffensive in the middle of 1944.4

Having suffered heavy losses of ground troops, aircraft, and pilots, the Japanese Army was unable to assume its share of preparations for the counteroffensive. Moreover, continuous shipping losses and Allied air attacks against the prospective bases made it impossible for the Japanese to send enough army troops forward even to defend those bases properly, let alone develop them to support major counterattacks.

Ever since its heavy losses in the middle of 1942, the Japanese Navy had been endeavoring to rebuild its air and surface strength for a naval showdown in the Pacific. Despite continued serious losses from Allied air and submarine operations through early 1944, the Japanese Navy was induced by the series of Allied carrier attacks and advances in the first four months of 1944 to speed preparations for the showdown. On this potential battle, the Japanese Navy conferred the code name Operation A or, as it was more euphoniously known, the A-GO Operation.5

The Japanese Navy initially planned to meet the U.S. Pacific Fleet for the A-GO Operation in the waters around the Palaus, but the possibility that the battle might have to be fought off the Marianas or near Geelvink Bay was not overlooked.6 Whatever the expected locale of the battle, the Allied invasions of Hollandia and Aitape on 22 April gave impetus to final preparations for A-GO. On 3 May the Navy Section of Imperial General Headquarters issued a warning order for all units of the Combined Fleet to start assembling for the A-GO Operstion.

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For the battle, the Japanese Navy organized the bulk of the Combined Fleet’s striking power into a unit called the 1st Task Force,7 under Vice Adm. Jisaburo Ozawa. Admiral Ozawa’s force was divided into two major sections: the 2nd Fleet, containing the battleships, cruisers, and destroyers of the battle line, and the 3rd fleet, which was a carrier striking force comprising nine carriers and their escorts, and based approximately 500 aircraft. Also scheduled to take an important part in the A-GO Operation was the land-based 1st Air fleet, commanded by Vice Adm. Kakuji Kakuta.

The 1st Air Fleet, with an authorized strength of over 1,600 planes (the bulk of them land-based types), had been organized in Japan in mid-1943. Comprising initially the 61st and 62nd Air Flotillas, it was to have had at least a year’s training which, apparently, was to emphasize land-based operations in support of fleet action. Continued Allied advances in the Central and Southwest Pacific Areas, the loss of the Japanese Navy’s carrier-based air strength at Rabaul, and Allied carrier attacks against Truk prompted Imperial General Headquarters, in February 1944, to send the bulk of the 61st Air Flotilla (accompanied by Headquarters, 1st Air Fleet) to the Marianas. Some of the 61st’s aircraft were simultaneously deployed to the Carolines and Palaus, while the 62nd Air Flotilla, lacking sufficient training for combat, remained in Japan.8

On 22 April, when the Allies landed at Hollandia and Aitape, the 1st Air Fleet was assigned the operational control of the 23rd Air Flotilla, then the only Japanese Naval Air Service unit based in New Guinea. Based since February 1942 variously at Kendari, in the Celebes, and at Davao, Mindanao, the 23rd’s headquarters moved to Sorong, at the northwest tip of the Vogelkop, in mid-April 1944. At that time the flotilla sent a number of its combat planes forward to Biak and Wakde.

Most of these planes were lost during the Allied carrier- and land-based air operations which prepared the way for the landings of the RECKLESS and PERSECUTION Task Forces. The 1st Air Fleet, when it took over operational control of the 23rd Air Flotilla, therefore sent to the latter unit fourteen land-based bombers. Earlier plans to send additional aircraft to the 23rd from the 61st Air Flotilla’s detachment in the Palaus had to be abandoned when the 61st lost over 100 planes during the U.S. Fifth Fleet carrier raids on the Palaus at the end of March.

The 23rd Air Flotilla could undertake no major counterattacks against Hollandia and was unable to do anything to prevent the Allied advance to Wakde–Sarmi on 17 May. Instead, trying to save its remaining strength, it withdrew most of its aircraft to Sorong, leaving only a few reconnaissance planes at Biak. Between the Allied landings at Hollandia and Biak, the flotilla devoted much of its time to maintaining air bases in the western New Guinea area in the expectation that more reinforcements would be sent to it from the 1st Air Fleet. But such additional strength was not immediately forthcoming. Instead, the 23rd Air flotilla suffered still more losses from Allied aircraft based at Hollandia and Wakde. When the

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HURRICANE Task Force landed on Biak, the flotilla still had only twelve fighters and six medium bombers.9

The Japanese Decision to Reinforce Biak

Meanwhile, final preparations for the A-GO Operation had been going on apace.10 The 1st Task Force assembled on 16 May at Tawitawi, outermost island of the Sulu Archipelago, which extends southwest from Mindanao toward Borneo. Then, just after the Allied landings in the Wakde–Sarmi area, the 1st Air Fleet was ordered to begin final deployment for A-GO. The U.S. Fifth Fleet attack on Marcus Island, northeast of the Marianas, on 20 May, apparently convinced the Japanese Navy that a major Allied advance was about to take place in the Central Pacific, bringing the U.S. Fifth Fleet into waters where the 1st Task Force, supported by the 1st Air Fleet, would have some advantages. Whatever the case, on 20 May the 1st Task Force was alerted to be ready to sally forth from Tawitawi to execute A-GO at a moment’s notice.

During conferences at Imperial General Headquarters in late April and early May, the question of what steps might be taken in case the Allies advanced to Biak before they moved in the Central Pacific had been considered by the Japanese Navy. The Japanese were apparently convinced at this time that the next major Allied target in the Central Pacific would be the Marianas, the seizure of which the Japanese Navy believed would be an unparalleled calamity which would foreshadow the loss of the war. Moreover, the Japanese Navy realized full well that A-GO was going to be fought on a shoestring, for it knew that available land-based air strength in the Marianas and Carolines was really inadequate for proper fleet support. If part of that already insufficient strength were redeployed to western New Guinea to protect Biak, the disparity between the striking power of the 1st Task Force and the surface vessel and carrier-based air strength available to the Allies would become even more decided than it was estimated to be.

The Japanese Navy therefore decided to send no more aircraft to western New Guinea other than the fourteen bombers which had been dispatched to the 23rd Air Flotilla late in April. It was planned, moreover, that there would be no naval reaction to an Allied landing on Biak beyond attacks which could be mounted from Sorong by the wholly inadequate 23rd Air Flotilla. Thus, possibly gambling that the A-GO Operation would take place before an Allied attack on Biak, and obviously considering the Marianas more important than the western New Guinea area, the Japanese Navy reconciled itself to the probable loss of the bases in the Geelvink Bay area.

But on 27 May there occurred the event which the Japanese Navy had possibly feared. The HURRICANE Task Force began

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pouring ashore at Biak at a time when Allied forces in the Central Pacific had made no move toward the Marianas. Suddenly the Japanese Navy had a change of heart and decided that the 1st Task Force would be at a marked disadvantage during A-GO if it had to cope with Allied aircraft using Biak fields.

To counter the Allied advance to Biak, the Japanese Navy decided upon two drastic steps. First, it dispatched from one third to one half (the figures vary according to source) of its available naval land-based air strength from the Central Pacific to reinforce the 23rd Air Flotilla in western New Guinea. On 28 May, 70 carrier-type fighters (50 of these were to stage in from Japan through the Philippines and were probably from the 62nd Air Flotilla), 4 reconnaissance bombers, and 16 medium bombers were ordered to western New Guinea. It also appears that another group of planes, comprising 48 fighters, 8 reconnaissance aircraft, and 20 bombers, was likewise ordered to move to western New Guinea and Halmahera from the Carolines on or about 31 May.

Thus, the Japanese Navy apparently planned to reinforce the 23rd Air Flotilla with 90 to 156 aircraft, the bulk of them fighter types. It is not known how many of these aircraft actually reached Sorong or other Vogelkop area bases, but it is known that most of the pilots, upon arrival in New Guinea, were immediately stricken with malaria or other tropical fevers and became liabilities rather than assets to the 23rd Air Flotilla. From the scale of the Japanese air effort against Biak,11 it would appear that few of the reinforcing planes were ever used in attacks on that island.

The Japanese Navy next decided that it was just as important to attempt to hold Biak as to stage air raids against the Allied forces on the island. The Biak Detachment was obviously not strong enough to prevent the Allies for long from occupying the entire island. Therefore, as the second step, the Japanese Navy, in agreement with the Army Section, Imperial General Headquarters, decided to transport to Biak the Army’s 2nd Amphibious Brigade. Moreover, the Navy was willing to risk major elements of the 1st Task Force to insure the brigade’s safe arrival on Biak. Orders to begin moving the 2nd Amphibious Brigade from the Philippines to Biak, an undertaking which the Japanese called Operation KON,12 were issued by Headquarters, Combined Fleet, on 30 or 31 May. At the same time it was decided to move three infantry companies of the 35th Division from Sorong to Biak, presumably by barge. Execution of these orders began immediately.

The KON Operation

The 2nd Amphibious Brigade, a relatively new unit of the Japanese Amy, had been formed and trained for assault landings and transportation by small craft. Originally, it had been about 4,000 strong and comprised three infantry battalions, a 75-mm. mountain artillery battalion of twelve guns, a tank company, and attached engineer, signal, medical, and other service-type units.

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The brigade had lost some of its infantry personnel and the entire tank unit as a result of Allied submarine action during the organization’s movement from Japan to the Philippines in April or May. Most of the brigade was finally moved from Manila to Zamboanga, while some of the unit was apparently sent to Davao.13

The First KON Operation

The KON Force, as the ships detailed from the 1st Task Force for the purpose of reinforcing Biak came to be called, was divided into four sections.14 The largest and most important was the Transport Unit, consisting of 1 heavy cruiser, 1 light cruiser, and 3 destroyers. Next were the 1st Screening Unit, 2 heavy cruisers and 3 destroyers, and the 2nd Screening Unit, 1 old battleship and 2 destroyers. A Detached Unit15 contained two mine layers and an unknown number of submarine chasers, patrol craft, and landing craft or barges. The Transport Unit was to move 1,700 troops of the 2nd Amphibious Brigade to Biak, while the Detached Unit took 800 more men of the same organization to the island. It appears that the Transport Unit and the 1st and 2nd Screening Units were also to shell Allied positions on Biak and attack Allied transport ships and naval vessels found in Biak waters.

According to orders, KON Force was to reach Biak on 3 June. There is no indication that the Japanese expected the KON Operation to evolve into an A-GO Operation in the Geelvink Bay area. Japanese reconnaissance aircraft, even as KON Force sailed toward Biak, were keeping under surveillance U.S. Pacific Fleet units stationed in the Marshall Islands. Should the scouting planes report that large groups of the American vessels had left the Marshalls, the Japanese would immediately put into effect their plans for A-GO. In accordance with these plans, the 1st and 2nd Screening Units of KON Force would hurry to rejoin the 1st Task Force in Philippine waters.

The KON Force’s Transport Unit left Tarakan, Borneo, on 30 May and arrived at Zamboanga, Mindanao, the next day. At Zamboanga, the unit’s cruisers and destroyers took aboard the 1,700 troops of the 2nd Amphibious Brigade and then moved on to reach Davao, Mindanao, on 1 June. The 1st and 2nd Screening Units departed the Tawitawi fleet anchorage on 30 May and assembled with the Transport Unit in Davao Gulf on 1 June. The three units left the gulf about midnight on 2 June, the 2nd Screening Unit following a course generally parallel to but some fifty miles east of the other two groups. To allow more time to embark troops and make final plans, there was a delay of one day in Davao Gulf, after which the ships of the three KON Force units were not expected to arrive off Biak until approximately 2200 hours on 4 June.

So far, various Allied intelligence agencies had kept fairly accurate track of Japanese ship movements in the Mindanao area by means of aerial reconnaissance and submarine reports. On 30 May the 1st and 2nd Screening Units had been sighted as they sailed east from Tawitawi. General MacArthur’s

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G-2 Section, interpreting this sighting, considered it probable that the Japanese ships were heading for Davao or the Palaus on supply or transport missions. At this time apparently little consideration was given to the possibility that the Japanese fleet units might have been sallying forth with offensive intent. The next day, 31 May, the ALAMO Force G-2 Section stated: “Enemy naval intervention at this stage of the [Biak] operations is impossible.”16

On 1 June Allied air or submarine (the record is not clear) sightings accounted for twelve of the thirteen ships comprising the three KON Force units then assembled in Davao Gulf. But, despite the fact that the G-2 Section of General MacArthur’s headquarters had also received information from radio intercepts indicating that the Japanese were planning to send the 2nd Amphibious Brigade to Biak, that section was still disinclined to believe that the Japanese fleet movements presaged offensive intent. Instead, it was considered more probable that the combat vessels at Davao Gulf were merely preparing to take supplies or reinforcements to Halmahera or perhaps to northwestern New Guinea.17

Early on the morning of 3 June, at a point just east of the Talaud Islands, between Mindanao and Morotai, a Seventh Fleet submarine sighted the Transport and 1st Screening Units and was in turn sighted by ships of the latter organization. Seventh Fleet PB4Y’s, operating from Wakde Island, kept the Japanese vessels under surveillance the rest of the day, reporting that the course and speed of the enemy ships could bring them into range of Biak during the evening of 4 June.18 Their discovery by Allied aircraft so far from Biak (about 650 nautical miles) apparently had not been anticipated by the Japanese, who later reported that they had not known Allied aircraft were capable of such long-range reconnaissance.19 Nevertheless, the three KON Force elements steamed on toward Biak, probably hoping that friendly aircraft might drive off the Allied reconnaissance planes and also protect the sea approaches to Biak.

In connection with KON Force’s advance, the Japanese had planned heavy air strikes against Biak which were to be carried out by the recently reinforced 23rd Air Flotilla and the few army aircraft which remained at bases within range of Biak. Between 1645 and 1700 on 2 June, from eleven to fifteen Japanese planes bombed Allied positions on Biak, causing a few casualties and some light damage. Seven of these planes were shot down by shore-based antiaircraft weapons, while guns aboard Seventh Fleet ships lying off Bosnek accounted for at least one more. Later during the same night, a few more enemy planes dropped some bombs harmlessly on and near Owi Island. Still more approached Biak during the night, causing many red alerts but not dropping any bombs. The next night, that of 3–4 June, no Japanese planes attacked Biak, although an unknown

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number bombed Owi Island without causing any damage or casualties. Again, however, enemy aircraft flew many reconnaissance flights around Biak, causing an almost continuous red alert until the early morning hours of 4 June.20

The Japanese reconnaissance aircraft around Biak probably lost for the Japanese their best opportunity to reinforce and bombard the island. Already worried at being sighted by an Allied submarine and shadowed by PB4Y’s, the KON Force, late on 3 June, received reports from Japanese scouting planes that an impressive Allied naval force, including carriers, was lying off Biak. How such a report could have originated is unknown—the pilots must have mistaken destroyers for battleships and LSTs for carriers—for there were no Allied naval vessels larger than destroyers at Biak on 3 June. The Japanese now believed that the surprise value of KON had been lost and they began to fear attacks from carrier-based aircraft. Therefore, at approximately 2000 hours on the 3rd, the KON Operation was called off.

Meanwhile, Allied General Headquarters, acting on the basis of new secret intelligence, had re-evaluated the available information concerning sightings of Japanese combat vessels. On 3 June the theater headquarters warned ALAMO Force, Allied Naval Forces, and Allied Air Forces that there were strong indications that the Japanese were going to make attempts to land reinforcements on Biak during the night of 4–5 June or on nights immediately following. The same day the Allied Naval Forces formed a special task force comprising 1 heavy cruiser, 3 light cruisers, and 10 destroyers—most of the readily available combat strength of the Seventh Fleet and the Royal Australian Navy except for a few destroyers already at Biak providing support for ground operations.

The ships of the hastily assembled task force were to rendezvous off Hollandia and depart that station in time to arrive at Biak by 1915 on 4 June. The small fleet was to destroy or drive off an equal or inferior enemy force attempting to bring reinforcements to Biak. In case a Japanese force of superior strength came within range, the Allied groupment was to retire toward Hollandia, presumably under cover of Fifth Air Force planes from Wakde. In connection with these plans there was set up a north-south boundary near Biak to separate areas of naval and air responsibility. Naval or air elements were not to cross this boundary except in cases of emergency or when in hot pursuit of Japanese vessels.21

Long before the Allied task force reached Biak on 4 June, the Japanese had canceled the KON Operation. Had the enemy force continued toward Biak, it might well have found the waters around that island free of Allied vessels. Moreover, the small Allied task force, under orders to withdraw in case a superior enemy fleet showed up, would have been opposed by 1 battleship, 3 heavy cruisers, 1 light cruiser, and 8 destroyers of the Japanese Navy. The Allied group would have had one more ship but would have been far outclassed in range and weight of fire

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power. The Allied force might have had some support of land-based air power from distant Wakde Island, but the boundaries between air and naval zones would have limited the use of this help and the planes could not, in any case, be expected to operate with maximum efficiency during the night hours when the naval engagement would have taken place. Be that as it may, the Japanese resolved the question of an Allied naval withdrawal from Biak by failing to press home their planned attack.

When the Japanese called off KON on 3 June, the Transport and the 1st and 2nd Screening Units were a little over 500 miles northwest of Biak and about 250 miles east-southeast of the Talaud Islands. At this point, the three forces were reorganized. The Transport Unit, accompanied by the three destroyers of the 1st Screening Unit, changed course for Sorong, while the 2nd Screening Unit and the two heavy cruisers of the 1st turned back toward Davao, which they probably reached late on 5 June. Of the ships moving to Sorong, the Fifth Air Force claimed to have sunk one destroyer and damaged at least two others. No substantiation of these contemporary claims is to be found in Japanese sources or later Allied reports. The Transport Unit and the 1st Screening Unit’s three destroyers arrived safely at Sorong during the evening of 4 June.22

The Detached Unit, which had been moving toward Biak from Zamboanga on an independent course far to the west of the other three sections of KON Force, had also changed its direction during the night of 3–4 June, and reached Sorong sometime on the 4th. At Sorong the Transport Unit unloaded the 1,700 men of the 2nd Amphibious Brigade. The six destroyers of the Transport and 1st Screening Units then proceeded southwest to Ambon where they refueled. The Transport Unit’s one heavy cruiser and one light cruiser sought shelter in Kaboei Bay, Waigeo Island, about 60 miles northwest of Sorong. On 6 June the heavy cruiser Aoba was attacked there by fifteen B-24’s of the Fifth Air Force. First reports were that at least two hits were scored on the cruiser, but it was later learned that the ship suffered no damage. Instead, it was able to take part in a second KON Operation.23

The Second KON Operation

After noting the Japanese invasion fleet scattering to the north and southwest on 4 June, the G-2 Section of ALAMO Force estimated that the Japanese had at least temporarily dropped all plans for reinforcing Biak.24 It was realized that the enemy could send troop-carrying barges to Biak if he chose to risk running the Allied air and naval blockade of that island, but further large-scale naval intervention was not expected.25 The G-2 Section was due for another surprise—the Japanese had no intention of giving up so readily.

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The enemy had discovered, probably as a result of aerial reconnaissance early on 4 June, that the Allied naval force in the Biak area contained no carriers. Therefore, sometime on the 4th, Headquarters, Combined Fleet decided to make another effort to reinforce and bombard Biak. For the second attempt, KON Force units were again divided into four elements. The first was the Transport Unit, containing three destroyers which had been part of the first KON Operation Transport Unit. The second section was the Screening Unit, also comprising three destroyers. For the second KON Operation there were two detached units—the 1st had one heavy and one light cruiser while the 2nd Detached Unit included the small craft and patrol boats which had put into Sorong at the end of the first KON.

The three destroyers of the Transport Unit were each to embark 200 infantrymen at Sorong. In addition, the destroyers of either or both the Transport and Screening Units were each to tow to Biak one landing barge crammed with troops, probably 30 to 50 men to a barge. It cannot be definitely ascertained to what organization the infantrymen of the second KON Operation belonged but it appears that the second KON Force planned to move the bulk of the 2nd and 3rd Battalions, 219th Infantry, 35th Division, from Sorong to Biak. Elements of both units were later identified on Biak.

On the morning of 7 June the Transport, Screening, and 1st Detached Units rendezvoused off Misoöl Island, about 100 miles southwest of Sorong. The Japanese now decided that only destroyers would be used for the reinforcement run to Biak. Leaving the two cruisers at Misoöl, the Transport and Screening Units proceeded to Sorong where they embarked troops and picked up their tows. The 1st Detached Unit moved to Ambon for fuel and supplies while the 2nd Detached Unit was ordered to be ready to sail toward Biak at a moment’s notice.

The Transport and Screening Units left Sorong about midnight on the 7th, following a northeasterly course parallel to the coast of the Vogelkop Peninsula. The course was to bring the ships about 25 miles off Kaap de Goede Hoop (Cape of Good Hope), which, lying about midway between Manokwari and Sorong, is the northernmost point of the Vogelkop. After dawn on the 8th, air cover was to have been provided by planes of the 23rd Air Flotilla. But the cape area was being patrolled by Allied aircraft on 8 June and, about 1330, the 23rd Air Flotilla cover of six planes was shot down or driven away by Fifth Air Force P-38’s.

Finding the air now free of enemy planes, American B-25’s dived to the attack, reporting the convoy as 2 light cruisers and 4 destroyers. Initially, it was claimed that 1 destroyer was sunk, 2 were left sinking, and the fourth was damaged. A few days later, destruction was reassessed as 4 destroyers sunk and 2 light cruisers chased to the northwest.26 These claims were exaggerated. One destroyer, the Harusame, was holed by a near miss and sank rapidly, the bulk of its crew being saved. Another destroyer was damaged by a bomb and took some water; two others were slightly damaged by strafing. Neither speed nor navigation was impeded for any of the three. The two light cruisers reported by the Allied planes were, of course, the other two destroyers. These

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two might have taken some evasive action by heading northwest for a short time, but as soon as the Harusame crew had been rescued and the Allied planes had disappeared, the convoy reformed and continued on toward Biak.27

About 1800 on the 8th, the Transport and Screening Units received a report from a Japanese aircraft that an Allied naval force comprising 1 battleship, 4 cruisers, and 8 destroyers was moving west at high speed from an undesignated point east of Biak. This report was at least partially correct. The Allied task force which had been formed on 3 June had again assembled on the 8th, having been alerted by reports of the air-sea battle off the Kaap de Goede Hoop. But the Japanese convoy commander apparently took this air reconnaissance report with at least one grain of salt—had not similar information received on 3 June proved inaccurate? The Transport and Screening Units steamed on, despite the fact that the Kaap de Goede Hoop action had put the force behind schedule.

At 2330 the two enemy groups were approximately forty miles off the north coast of Soepiori Island, ready to turn southeast toward Korim Bay, on the northeast side of Biak. Minutes later a destroyer in the van sighted the Allied task force heading northwest around Biak. The convoy commander quickly realized that he was badly outnumbered and decided that discretion was called for. The destroyers with tows cut the barges loose and joined in a general flight northwest toward the Mapia Islands, almost 200 miles distant, with Allied destroyers in pursuit.28

Principally because the enemy had a long head start and was taking evasive action over miles of open sea, the Allied destroyers were unable to close with the Japanese ships. Moreover, the strength of the enemy force was unknown, and the Allied destroyers rapidly drew away from their cruiser support. Land-based air support was not available because of increasingly threatening weather, darkness, and the fact that previously assigned boundaries between aircraft zones and naval action could not readily be changed. Finally, at 0230 on the 9th, when the two opposing groups of destroyers were in the vicinity of the Mapia Islands, contact was broken and the Allied ships withdrew toward Biak.

The results of the engagement, during which only long-range destroyer fire had been exchanged, were inconclusive. A Japanese destroyer—one which had been hit on the 8th when the Harusame had been sunk—received more damage but again was able to continue on course without much loss of speed. In addition, Allied destroyers sank at least one of the barges which the Japanese destroyers had cut loose. Nevertheless, other barges of the group certainly managed to set reinforcements ashore, probably at Korim Bay, during the night.29

Japanese air cover at Biak for the second KON Operation had been practically nonexistent.

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Early on the morning of 8 June a lone enemy plane dropped a few bombs near shipping anchored off Mios Woendi and on the HURRICANE Task Force’s amphibian tractor pool. No damage to equipment resulted from this raid and only one man was wounded. About 2030 on the 8th, one fighter and two bombers attacked searchlight positions on Owi Island without causing any damage or casualties. Other enemy planes approached within radar range of Biak during the early morning hours of 9 June, but did not attack the island.30

During the melee in the Biak–Mapia area, the second KON Force’s Transport and Screening Units became separated, but even so, both steamed westward on divergent courses under cover of bad weather on the 9th. The Transport Unit’s destroyers proceeded to Sorong and there unloaded the 600 infantrymen so futilely carried toward Biak. The destroyers then rendezvoused with the cruisers of the 1st Detached Unit and the two groups sailed to Batjan Island, where they arrived on 10 June. The Screening Unit’s remaining two destroyers reached Batjan either late on the 9th or early on the 10th. Meanwhile, two heavy cruisers and two destroyers of the first KON Force had moved from Davao to Batjan and, during the movement, lost the destroyer Kazegumo to a Seventh Fleet submarine. The remaining three ships arrived at Batjan sometime on 9 June.

During these scurryings over vast stretches of the western Pacific, the small craft of the 2nd Detached Unit had perhaps been ordered to Biak. Whatever its original orders, the unit’s instructions were changed and the small craft apparently put back into Sorong on 10 June. There the 800 men of the 2nd Amphibious Brigade, who had been in transit from Zamboanga since 1 June, disembarked.31

A final and unexplained movement occurred during the night of 9–10 June, when Allied aircraft reportedly sighted between three and five unidentified warships about 150 miles north of the Mapia Islands. When first sighted the vessels were heading southeast toward Biak, and a later report, which identified the ships as Japanese destroyers, placed them fifty miles southeast of the Mapia group, still heading toward Biak at high speed. Japanese sources make no mention of a destroyer force at the specified time or place. Allied naval vessels, based at Mios Woendi, searched in vain in waters north of Biak for the Japanese ships during the early morning hours of 10 June.32 The maneuvering may have been an unrecorded Japanese attempt to entice Allied surface forces away from Biak so that barges could slip reinforcements into Biak from the southwest. More likely, however, the sighting reports were inaccurate as to location and course.

Whatever the facts concerning the shipping sighted on the night of 9–10 June, the ALAMO Task Force reported to ALAMO Force that the enemy warships were five destroyers which were moving reinforcements to Biak. It was partially on the basis of this report that General Fuller, on 13 June, requested ALAMO Force to send an additional infantry regiment to Biak.33

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The second KON Operation had cost the Japanese 2 destroyers sunk, 1 badly damaged, 2 lightly damaged, and at least 1 bargeload of infantrymen lost. In return for these losses, the enemy managed to land perhaps 100 fresh troops on Biak from the barges towed by the destroyers of the second KON Force. Finally, the Japanese had tied up a small Allied Naval task force for some days and had prompted the HURRICANE Task Force to call for reinforcements—a fact which the enemy did not learn for some days. But, despite the obvious lack of success of two attempts to reinforce Biak, the Japanese were determined to try again.

The Third KON Operation

During the second KON Operation the Japanese had not neglected to keep track of U.S. Fifth Fleet movements.34 On 9 June Japanese aerial reconnaissance noted that strong American carrier task forces had departed from the Marshall Islands. The Japanese realized that this movement presaged a new amphibious attack or, at least, a heavy carrier strike by Allied fleet units. But the enemy was not yet sure where the blow would fall. Nonetheless, on the morning of 10 June all units of the Combined Fleet were alerted to make final preparations for the A-GO Operation. Some naval air units had at this time started from Central Pacific bases toward Halmahera, presumably to support the KON Operation or to give added strength to enemy air deployment in the western New Guinea area. Now, these movements were canceled and the air units which had already started changing their stations were called back to the Marianas, Palaus, and central Carolines. Either on the 10th or a few days later, other air organizations which had already arrived in western New Guinea to reinforce the 23rd Air Flotilla were also ordered to return to their Mariana and Caroline bases. But, pending arrival of more information concerning intentions of the U.S. Fifth Fleet, the Combined Fleet decided to go ahead with a third KON Operation. In fact, plans for a third attempt had been initiated even as the destroyers of the second KON Force had been fleeing toward Batjan Island.

On the morning of 10 June the Combined Fleet issued orders organizing the third KON Force. Again there were to be four elements. The first was designated the Attack Unit and contained 2 battleships—the Yamato and Musashi, then the most powerful battleships in the Japanese or any other navy—2 heavy cruisers, 1 light cruiser, and 3 destroyers. A 1st Transport Unit comprised 1 heavy cruiser, 1 light cruiser, and 4 destroyers, while a 2nd Transport Unit included the small craft which had carried the 800 men of the 2nd Amphibious Brigade to Sorong. A Supply Unit was made up of two destroyer-escorts and two small cargo transport ships.

Available sources provide somewhat incomplete and contradictory information on Japanese plans for the employment of the powerful task force assembled for the third KON. Apparently, the first priority was to

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move reinforcements to Biak regardless of cost to ships or men. The second priority was for the Attack Unit to destroy Allied warships and merchant vessels found in Biak waters and to deliver a heavy bombardment against the HURRICANE Task Force’s shore positions. Some enemy sources indicate that the 1st and 2nd Transport Units were to take the 2nd Amphibious Brigade from Sorong to Biak, but only if an excellent opportunity to do so were presented.

The KON Force commander decided to gather his forces for the third KON Operation at Batjan Island. Most of the ships of the Attack Unit left the Tawitawi fleet anchorage on 10 June and arrived at Batjan on the 11th, rendezvousing there with the vessels of the second KON Force and with the first KON Force’s cruisers and destroyers. By morning of the 12th all elements of the third KON Force had assembled and were making final preparations for the third attempt to reinforce and bombard Biak.

But on 11 June carrier-based planes of the U.S. Fifth Fleet began heavy strikes against Japanese installations on the Mariana Islands. These attacks continued on the 12th. Apparently the Japanese were not sure at first what these raids portended, and they merely delayed the sailing of the third KON Force until more information concerning American intentions could be obtained. On the 13th, however, evidently satisfied that a full-scale invasion of the Marianas was about to take place, the Combined Fleet decided that the time had come to assemble all available forces for the A-GO Operation. The 1st Task Force had started northeastward from Tawitawi on the 12th. Now, on the 13th, the bulk of the third KON Force vessels left Batjan Island and headed northeast at full speed toward the Palaus to rendezvous with the 1st Task Force. The third and final threat to Allied naval and ground forces at Biak was over.

Reinforcements by Barge During KON

In attempting to follow the various phases of the KON Operation, it is all but impossible to separate the wheat from the chaff. On the surface it appears that the enemy’s major ambition was to reinforce Biak by means of large-scale naval intervention. But—although Japanese records give no inkling of this—the movements of the three KON Forces may also have been designed to confuse Allied naval units at Biak and draw them north of the island while barges slipped reinforcements into Biak from the southwest without naval protection. Whatever the facts of possible Japanese deception measures may be, suffice it to say that the 2nd Area Army dispatched other reinforcements to Biak by barge while Allied and Japanese naval vessels were maneuvering north and northwest of the island.

On 30 or 31 May, as the first KON Force was being organized, approximately 375 men of the 2nd Battalion, 221st Infantry, 35th Division, were loaded on barges at Manokwari and sent off toward Biak. The provisional groupment, known as the Ozawa Force, apparently contained the 6th and 7th Companies, the 2nd Machine Gun Company, 2nd Battalion headquarters, and possibly a detachment of the 221st Infantry’s signal section. Probably making an overnight run from Manokwari, the Ozawa Force reached Noemfoor Island on 1 June,35

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but from Noemfoor on, the unit’s movements are harder to trace.

Apparently, part of the Ozawa Force (comprising the 6th Company, two light artillery weapons, and Captain Ozawa’s headquarters) reached Korim Bay, Biak, on the night of 3–4 June and then proceeded southwest overland to reach the West Caves area on the 9th. Some troops were lost on the way to Biak and other barges may have turned back to Noemfoor. The rest of the Ozawa Force seems to have left Noemfoor about 10 June, reaching Korim Bay on the 12th. Other elements of the 2nd Battalion, 221st Infantry, including the bulk of the 5th Company, apparently left Manokwari for Biak on or about 7 June, and some men of this echelon may have reached Biak. It is impossible to ascertain how many men of the 2nd Battalion, 221st Infantry, finally arrived on Biak, but it appears that the total did not exceed 400.36

Either the 2nd or 3rd Battalions of the 219th Infantry, originally at Sorong, had been involved in the second KON Force’s destroyer run and barge tow to Biak during 7–9 June. On the night of the 8th perhaps 100 men of one of these battalions had managed to reach shore at Biak when the destroyers had cut loose their tows and fled toward the Mapia Islands. The remaining elements of the 219th Infantry, aboard the destroyers, returned to Sorong on the 9th. On the same day most of the 2nd Battalion (which may or may not have been involved in the destroyer run) was loaded on barges at Sorong and sent to Biak via Noemfoor Island. It is not known when the Nishihara Force, as the unit organized for the barge run was designated, reached Noemfoor, but it must have been about 12 June. One company apparently left for Biak the next day, while the rest of the force seems to have waited until the 16th. In any case, the Nishihara Force began reaching the fighting area north of Mokmer Drome on 23 June.37

The 5th and 9th Companies of the 222nd Infantry, Colonel Kuzume’s own regiment, had not been on Biak when the HURRICANE Task Force began landing on 27 May. The 5th Company, garrisoning Noemfoor since early April, was ordered to Biak about 30 May, while the 9th Company, which was either at Noemfoor or Sorong, was apparently alerted for the move to Biak about the same time. How the two units moved to Biak is not certain, but it seems most probable that the 5th Company sailed from Noemfoor with the Ozawa Force. At any rate, it arrived in the West Caves area on the 10th of June, having lost some men in transit. The 9th Company probably moved with the Nishihara Force to Noemfoor (if it had been at Sorong) and left the island aboard three large barges on or about 20 June. One of these barges, carrying about thirty men and all the heavy weapons and supplies of the company, was sunk by a Seventh Fleet PT boat not far from Noemfoor. The other two apparently put back to Noemfoor to try again a few days later, the

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remnants of the company reaching Biak about 25 June, possibly in company with part of the Nishihara Force.38

Thus, over a period of about one month, the Japanese managed to reinforce the Biak Detachment with approximately 1,200 men—about 225 troops of the 222nd infantry, some 400-odd of the 221st Infantry, and probably a little over 500 of the 219th Infantry. Considering their naval, air, personnel, and supply losses during the KON Operation and the barge runs, and also considering the fact that the reinforcements were too few and too late to affect the outcome of operations on Biak, the Japanese attempt was hardly worth the effort.

Results of the KON Operation

Facts and Speculation

It is difficult to assess the effect the Japanese Navy’s attempts to hold, reinforce, or attack Biak may have had on subsequent naval operations throughout the Pacific, especially during the A-GO Operation, which was known on the Allied side as The Battle of the Philippine Sea and which occurred off the Marianas in mid-June. It is known that Combined Fleet plans for A-GO had placed a great deal of dependence upon the support of naval land-based aircraft. Units of the 1st Air Fleet, based in the Marianas, Carolines, and Palaus, had been expected to effect reconnaissance ahead of the 1st Task Force and attack Allied shipping, aircraft, and combat vessels as the 1st Task Force sallied forth to battle against the U.S. Fifth Fleet.

But when the Allies landed on Biak, one third to one half of the 1st Air Fleet’s planes had been sent to western New Guinea to support KON. Other elements of the 1st Air Fleet were evidently dispatched from Central Pacific bases toward Halmahera and western New Guinea on or about 10 June. Of the first group, at least half the pilots were lost as the result of malaria or action in support of KON. Most of the remaining pilots were lost to Allied air action or bad weather as they tried to get back to Central Pacific bases after 13 June, when the Japanese started A-GO. The pilots and planes which had started redeployment southwestward about 10 June were similarly lost or were caught out of position.

Bad weather had prevented the Japanese from sending additional air reinforcements from Japan to the Marianas, and U.S. Fifth Fleet strikes against those islands beginning on 11 June accounted for most of the remaining planes of the 1st Air Fleet. According to Japanese figures, only 20 percent of the 1st Air Fleet strength originally deployed in the Central Pacific was available for A-GO, the rest having been lost during operations in western New Guinea, caught out of position as a result of untimely redeployments in support of KON, or destroyed by U.S. Fifth Fleet carrier raids before the 1st Task Force could get in position for its own attack. Indeed, the latter’s deployment for A-GO had possibly been delayed as a result of preoccupation with KON. What the outcome of A-GO might have been had not so much of the 1st Air Fleet’s land-based strength been redeployed for KON can only be conjectured. It is possible that A-GO might have been much less disastrous for the 1st Task Force; the U.S. Fifth Fleet might have suffered severe losses; it might have been next to impossible

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to supply the Allied forces of the Central Pacific ashore on the Marianas; and Allied operations throughout the Pacific might have been delayed. Whatever the facts, Japanese sources almost uniformly lament redeploying so much of the 1st Air Fleet’s strength southwestward to support the KON Operation.39

The Central Pacific’s invasion of the Marianas, with the concomitant withdrawal of the KON Force for A-GO, could hardly have occurred at a more auspicious moment for the Allied forces of the Southwest Pacific. While the Allied Air Forces were prepared for the eventuality that Japanese fleet units might reach Biak, air operations might well have been curtailed by range and weather factors, as, indeed, they had been during the second KON Operation. In any case, the Allied Air Forces would have had a tough job driving the KON Force away from Biak, especially if the 1st Air fleet’s strength in the western New Guinea area had been built up as planned. Had the powerful task force which the Japanese assembled for the third KON attempt reached Biak, it probably could have overwhelmed any naval force the Allied Naval Forces could have mustered there. Even had the third KON Force not landed any troops at Biak, its fire power might have made untenable the HURRICANE Task Force’s coastal positions and its hold on Mokmer Drome. Had the Allied vessels at Biak been sunk or driven off, supplying Biak would have been a major problem until the Japanese fleet units were forced to retire and the Allied ships were replaced. Although the total force the Japanese hoped to land on Biak—probably some 5,000 men, all told—could not have driven the HURRICANE Task Force into the sea, such reinforcements would have rendered the Allied unit’s task infinitely more difficult and inevitably would have necessitated its reinforcement, perhaps by as much as an entire infantry division.

In June 1944, the Allied Forces of the Southwest Pacific Area probably had little idea how potentially dangerous the situation was at Biak, and it remained for postwar Japanese reports to reveal how narrowly greater losses and strategic delays were averted. Without doubt, success for the Japanese during KON would have seriously delayed the pace of Allied operations in the Southwest Pacific Area, if not throughout the Pacific. The “if” connection between KON and A-GO is obvious—the success of either would have been a devilish blow. The close relation between the two operations is a striking illustration of the mutual interdependence of the Allied Southwest and Central Pacific Areas.

Effects of KON at Biak

Insofar as Japanese ground forces in the Southwest Pacific were concerned, the cancellation of KON and the departure of KON Force vessels to the Central Pacific battle area left the 2nd Area Army in an unenviable position. General Anami had pinned his strategic hopes on reinforcing Biak, but now the best means of so doing had been taken away. On orders from higher headquarters, he had to concentrate the 2nd Amphibious Brigade at Sorong,

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but he determined to send the rest of the 35th Division to Biak. Apparently this was to be accomplished by barges, aided by such escort vessels as might be left to the Southwestern Fleet.

Since it was becoming increasingly dangerous for barges to move beyond Sorong, General Anami finally decided to await the outcome of the A-GO Operation before sending any more elements of the 35th Division to Biak, although he continued to move parts of the division from Sorong to Manokwari. When the Japanese Navy was defeated in A-GO, General Anami realized he would have no further opportunity to send large bodies of troops to Biak. He therefore ordered the 35th Division to remain at Manokwari. Hoping for the longest possible delay of Allied operations at Biak or subsequent advances, he instructed the Biak Detachment not to commit suicide in fruitless banzai attacks, but rather to prolong the action by protracted defense and, in the end, by guerrilla warfare. The last significant attempts to reinforce Biak were the movements of the Nishihara Force and the 9th Company, 222nd Infantry, late in June.

On Biak Colonel Kuzume committed the reinforcements which reached the island piecemeal to operations along the low ridge north of Mokmer Drome. At least one company of the 221st Infantry was in position there on 10 June and the rest of the Ozawa Force, initially held in reserve at the West Caves, was sent into defenses along the low ridge by the 13th. The 5th Company, 222nd Infantry, also moved into the line in the same area on the 10th, and 100 men of the 219th Infantry were in the vicinity of the West Caves by the same date. Late in the month, the Nishihara Force and the remnants of the 9th Company, 222nd Infantry, were slipped in the line near the West Caves.40

Most American analyses of Japanese operations on Biak condemn Colonel Kuzume for misuse of his reinforcements, stating that he should have concentrated them for a counterattack. But whether, in fact, the Biak Detachment commander could have used his additional strength in other than defensive activities is problematical. The reinforcements arrived on Biak in small increments, none over 400 men strong. The total was not more than 1,200 troops, most of whom brought ashore only light infantry weapons. Moreover, Colonel Kuzume undoubtedly knew something of the difficulties attending the KON Operation. He had no assurance that strong reinforcements would reach him, nor did he know when they might arrive. Therefore, as fresh troops landed on Biak, Colonel Kuzume put them into the line north of Mokmer Drome, where he apparently thought they would do the most good. Under continuous artillery bombardment and infantry attack, the Biak Detachment’s forces along the low ridge were suffering great losses. The Japanese commander’s primary mission was to prevent the Allies from employing the Biak airfields—a mission which he could accomplish from positions along the low ridge—and he used his reinforcements to aid him in this task.41

Although the Japanese were unable to send sufficient reinforcements to Biak to affect

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the ultimate outcome of operations there, enough fresh troops did reach the island to delay Allied employment of the Biak airstrips; to prompt General Fuller to ask for reinforcements on 13 June; and, at least indirectly, to have something to do with changes in the Allied command at Biak. Under the new command—General Eichelberger in control of the HURRICANE Task Force and General Doe in command of the 41st Infantry Division—the attack was continued.