While the Japanese forces in the Philippines hastened to complete preparations against anticipated Allied invasion, enemy carrier-borne aircraft served sudden warning on 9 September 1944 that the date of this invasion was fast drawing near.1 In the first large-scale air operation by the Allies against the Philippines, an estimated 400 carrier planes staged a devastating ten-hour offensive against southern Mindanao, concentrating their attacks on Davao, Sarangani, Cagayan and Digos.
Since Japanese air patrols had failed to discover the enemy task force,2 the attacks achieved complete surprise and inflicted widespread and severe damage to ground installations, airfields, anchorages, and lines of communication. Reconnaissance units of the First Air Fleet immediately flew off search missions, which revealed that the attacks originated from three enemy naval task groups boldly maneuvering in the waters southeast of Mindanao. Two of these groups were reported to have nuclei of two aircraft carriers each; the composition of the third was not ascertained.
The First Air Fleet's 153d Air Group was the only combat flying unit actually based at fields in the Davao area at the time of the strike.3 Despite damage to some of its fighter aircraft which were caught on the ground, this unit, as well as the 761st Air Group's torpedo bombers based at Zamboanga, were in a position to attack the enemy carrier groups had Vice Adm. Teraoka, First Air Fleet Commander, ordered such action. However, the Sho-Go Operation plans covering employment of the air forces rested on the basic tactical principle of not committing those forces against pre-invasion raids by enemy task forces, but conserving their strength for all-out attacks when the enemy was about to launch actual landing operations. The First Air Fleet therefore withheld retaliatory action pending further developments.
Ground and naval units in the Davao area were nevertheless ordered on the alert to meet the possible contingency that an invasion attempt would follow the air strikes, and the Japanese armed forces throughout southern Mindanao became tense with expectancy. A
feeling of nervousness gripped the weak local forces at Davao4 and rapidly spread to the large Japanese civilian colony. A wave of wild rumors swept the city. On 10 September, a second series of heavy enemy raids aggravated this state of alarm. The city and harbor were reduced to a shambles and communications paralyzed. Panic and civil disorder broke out.
In the midst of the alarm and confusion caused by the air strikes, a 32d Naval Base Force lookout post on Davao Gulf suddenly sent in a report at 0930 on 10 September that enemy landing craft were approaching the shore.5 The Base Force headquarters hastily transmitted the report to the First Air Fleet, which in turn radioed all navy commands affected. Not until mid-afternoon, several hours after the report had been broadcast, was it established by air reconnaissance over the gulf that there were actually no enemy ships present. The First Air Fleet thereupon radioed at 1630 that the previous report was erroneous.6
In the interim, however, higher army and navy headquarters had reacted swiftly. Admiral Soemu Toyoda, Commander-in-Chief of the Combined Fleet, had ordered all naval forces alerted for the execution of Sho Operation No. 1. Thirty-fifth Army headquarters at Cebu had simultaneously issued an alert for Suzu No. 1 Operation, applicable to an enemy invasion of the Davao area.7 The 30th Division main strength in the Cagayan area was ordered to prepare immediately to move to Davao to reinforce the 100th Division, and the 102d Division in the Visayas was directed to release two infantry battalions for dispatch to Mindanao. The Fourth Air Army meanwhile issued orders directing the 2d Air Division elements which had just advanced to Menado for the purpose of reinforcing the 7th Air Division8 to return immediately to Bacolod.9
Following receipt of the First Air Fleet's retraction of the earlier invasion report, the Combined Fleet and Thirty-fifth Army cancelled the Sho No. 1 and Suzu No. 1 alerts late on 10 September. The whole incident, however, had a vital influence on later developments. The acute embarrassment caused by the false landing scare made military and naval commanders excessively chary of accepting later invasion reports at face value.10
Less than 48 hours after the termination of the raids on Mindanao, the enemy struck again; this time in the central Philippines. On the morning of 12 September, a navy radar picket station on Suluan Island, in Leyte Gulf,
broadcast over the general air-warning net that a vast formation of enemy carrier planes was heading westward toward the Visayas. Since the Suluan Island lookout was only about twenty minutes' flying time from Cebu, the air forces there could not be alerted quickly enough to put up an effective defense. By 0920 the enemy planes were already swarming over the Cebu airfields, where the main fighter strength of the First Air Fleet was based following its transfer from Davao. Although the attacks extended over the entire Visayan area and later took in Tawitawi, in the Sulu Archipelago, the Cebu fields appeared to be the principal objective.
In the three days over which this air offensive continued, the First Air Fleet suffered damage to 50 Zero fighters on Cebu alone, while in other areas 30 additional aircraft of all types were rendered non-operational. Flight personnel suffered numerous casualties, and training was disrupted.11 Heavy damage was also sustained by Army air units. The 13th Air Brigade, made up of Type I fighters, was so hard hit that it had to be ordered back to Japan for regrouping, while the 45th Fighterbomber Regiment was reduced to half strength. In addition, 11 transports totalling 27,000 gross tons and 13 naval combat vessels were sent to the bottom of Cebu harbor.12
The carrier raids on Mindanao and the Visayas at once strengthened the conviction of the Southern Army command that the Allies were preparing for an early invasion of the Philippines. At the same time, they had shown all too clearly that the tactical policy of not committing available air strength against raiding enemy task forces was open to serious question as a means of conserving that strength for subsequent decisive battle. After carefully studying the over-all situation, Field Marshal Terauchi and his staff therefore prepared recommendations to Imperial General Headquarters substantially as follows.13
Although these recommendations were put into final form prior to 15 September, Marshal Terauchi desired to back them up with a simultaneous and full report on the damage done by the Allied carrier air strikes of 9 and 12 September. He therefore delayed forwarding them pending receipt at Manila of reports from all sectors which had been attacked. Col. Yozo Miyama, senior operations officer of Southern Army, was ordered to proceed to Tokyo by air to place the recommendations and report before Imperial General Headquarters, finally leaving Manila on 18 September.14
Meanwhile, it had already become apparent that the enemy's carrier strikes against Mindanao and the Visayas were not the prelude to a direct invasion of the Philippines themselves, but a cover for the launching of preliminary amphibious assaults on two vital defensive outpoststhe Palau Islands in the western Carolines and Morotai in the northern Moluccas.
Indications that the enemy contemplated an immanent invasion of the Palau group, strategic eastern gateway to the Philippines, had been mounting for some time. Following a threeday carrier air strike against the islands late in July, enemy planes had continued small-scale attacks and reconnaissance activity throughout August. With the beginning of September, powerful carrier-borne forces launched a new offensive of full pre-invasion intensity, carrying out daily attacks which continued almost without interruption through 14 September. By the latter date, these attacks had done severe damage to antiaircraft installations, gun emplacements, beach defenses, and vital supply dumps.15
While the enemy's carrier aircraft pounded targets throughout the Palau group, strong surface elements also subjected the southernmost islands of Peleliu and Angaur to a series of heavy naval gunfire bombardments directed against shore defense positions. These bombardments reached greatest intensity on 12 September, when the island of Peleliu received a concentration of 2,200 rounds of gunfire, knocking out important defense installations and communications facilities.16
At 0730 on 15 September, following a final sharp naval gunfire and air preparation, the enemy began landing on Peleliu with an estimated strength of one infantry division and more than 150 tanks. The landing caught the bulk of the Japanese defense forces concentrated on Babelthuap, the main island of the Palau group, with only minor 14th Division and other elements present on Peleliu to contest the invasion.17 The heavily outnumbered garrison fought tenaciously, but the enemy suc
ceeded in expanding the initial beachhead so rapidly that, by 19 September, the fighting had moved into the central highlands.
Troop reinforcements were subsequently ferried in to bolster the defense, and naval seaplanes operating from secret bases on Babelthuap carried out night attacks on the American forces. Nevertheless, Peleliu airfield remained securely in the enemy's hands. American fighter aircraft began using the airdrome operationally from 27 September.18
Meanwhile, the enemy had already moved to expand his foothold in the Palau group by invading the small island of Angaur, southwest of Peleliu. At 0900 on 17 September, a strong force, supported by the usual air and naval gunfire preparation, began landing in the face of scattered resistance by the small Japanese garrison of one infantry battalion, an artillery battery, and a handful of miscellaneous troops.19 The island was quickly overrun, and the fate of the defenders was never known.
Babelthuap still remained in Japanese possession, but the enemy had apparently achieved his objectives with the capture of Peleliu and Angaur and made no attempt to invade the main island. From rapidly developed bases on Peleliu and Angaur, enemy air power not only could keep the forces on Babelthuap helplessly pinned down in their hill positions,20 but could effectively deprive the entire western Carolines of any further value to the Japanese as a defensive outpost guarding the eastern sea approaches to the Philippines.21
Concurrently with the enemy advance to Palau on the Central Pacific front, General MacArthur's forces in Western New Guinea had also taken an essential preliminary step toward the final reinvasion of the Philippines by landing on the strategically situated island of Morotai, off the northeast coast of Halmahera.
Ever since the seizure of Sansapor by MacArthur's forces in July, the Second Area Army command at Menado had anticipated an early enemy invasion of the Moluccas, estimating that the main island of Halmahera would be the most probable target of attack. Throughout August and the first part of September, Allied air raid on Halmahera steadily increased in both weight and frequency. When a Japanese reconnaissance aircraft, on 11 September, reported a heavy concentration of enemy invasion shipping in Humboldt Bay, Hullandia,22 it appeared likely that the anticipated drive was about to get under way.
Inadequate troop as well as air strength had seriously impeded Second Area Army efforts to bolster the defenses of the Halmahera-Morotai area. The 32d Division under Lt. Gen. Yoshio Ishii, which was the principal combat force charged with the defense of the area, was understrength due to heavy losses suffered en route from China in May.23 Lt. Gen. Ishii initially assigned two battalions of the 211th Infantry Regiment to garrison Morotai, but in mid-July, as General MacArthur's offensive neared the western tip of New Guinea, this force was withdrawn to bolster the thinly-spread Japanese troops on Halmahera itself.24
Upon the withdrawal of the 211th Infantry elements, Lt. Gen. Ishii assigned the mission of securing Morotai to a small, provisionallyorganized force designated as the 2d Provisional Raiding Unit.25 The advance echelon of this force arrived on Morotai on 12 July, but its meager strength led the 32d Division, on 30 July, to order the construction of dummy positions and encampments, the lighting of campfires throughout the jungle, and other measures of deception to lead the enemy to believe that the island was strongly held.26
By 19 August the remaining strength of the 2d Provisional Raiding Unit had arrived, followed on 13 September by elements of the 36th Division Sea Transport Unit. Troop strength still remained dangerously low, however, and had to be so thinly disposed that it was completely impossible to plan an effective defense.27 Maj. Takenobu Kawashima, 2d
Provisional Raiding Unit commander, deployed his small combat force chiefly in the southwest sector of the island, while the remaining miscellaneous elements were scattered in lookout posts and security detachments around the island perimeter.
This was the situation when, at 0600 on 15 September, an enemy amphibious task force of about 80 ships appeared off Cape Gila and began shelling the entire southwest corner of Morotai. Following this gunfire preparation, reinforced by attacks from the air, the enemy put ashore a force estimated at one division. The 2d Provisional Raiding Unit, unable to offer effective resistance to the overwhelming enemy force, retired in good order, and by early morning of the 16th, the beachhead had been expanded to the Tjao River.28 (Plate No. 84)
While Maj. Kawashima endeavored to assemble sufficient strength for a small-scale counterattack, 7th Air Division planes, operating from bases on Ceram and the Celebes, launched a series of nightly hit-and-run raids with small numbers of aircraft, aiming principally at enemy shipping.29 These attacks had little more than a harassing effect, and the enemy, having reached the Tjao River, paused to consolidate his gains, at the same time hastening construction on the airfield at Doroeba.
On 18 September the main body of the 2d Provisional Raiding Unit, which had moved into position along the upper Tjao, launched a strong night infiltration attack with the objective of disrupting the enemy's rear area in the vicinity of Doroeba and Gotalalmo. Although deep penetration of the enemy lines was achieved and considerable casualties inflicted, the attack failed to reduce the beachhead or to interfere with the enemy's rapid preparation of Doroeba airfield. On 20 September enemy fighters began using the strip.
The 32d Division command on Halmahera had realized from the very beginning that successful development of an enemy base of air operations anywhere in the Moluccas would seriously compromise the future defense of the Philippines. Lt. Gen. Ishii therefore took immediate steps to reinforce Maj. Kawashima's forces, ordering the 211th and 212th Infantry Regiments and the 10th Expeditionary Unit to organize temporary raiding detachments for immediate dispatch to Morotai. The 210th Infantry Regiment was also ordered to prepare one battalion as a follow-up force. On 25 September the three raiding detachments were ordered to proceed to Morotai as follows:
Although the detachments successfully car-
ried out their movement to Morotai according to plan, strong enemy patrols which had been landed at various points around the perimeter of the island blocked the use of the coastal tracks, forcing the reinforcement units to move through the jungle. Three weeks thus elapsed before the detachments were able to complete their juncture with the 2d Provisional Raiding Unit on 20 October.30 In the interim, Maj. Kawashima's force had continued to execute nightly raids against the enemy defense perimeter, without any appreciable effect, however, in deterring the use of Doroeba airfield. On 28 September multi-engined enemy bombers were observed using the field.
Studying the unfavorable developments on Morotai, the Second Area Army command decided that more energetic action must be taken to bar the enemy from making effective use of the Doroeba base. On 8 October, therefore, Lt. Gen. Takazo Numata, Second Area Army Chief of Staff, radioed the following instructions to the commander of the 32d Division:
In compliance with this directive, Lt. Gen. Ishii planned to dispatch additional reinforcements composed of the main strength of the 210th Infantry Regiment and elements of the 211th Infantry and 18th Shipping Engineers. Meanwhile, under earlier plans, the 3d Battalion, 210th Infantry, had already embarked for Morotai, landing on 9 October in the Boesoboeso sector on the southeast coast. From there it began a grueling, costly trek through the jungle to join the 2d Provisional Raiding Unit in, the Pilowo-Sabatai River area.31
Without waiting for the arrival of the battalion, the 2d Provisional Raiding Unit in mid-October began a new series of night infiltration raids, some of which penetrated to the airfield itself. Substantial casualties were inflicted on the enemy, and considerable damage was done to rear installations.32 It nevertheless proved impossible to achieve the central objective of denying the use of the field to the enemy air forces.
Despite strong reinforcements which reached Morotai from Halmahera during the next two months,33 the enemy's hold could not be shaken, nor could the Japanese forces effectively prevent the development of the island into a valuable advance base of operations for Allied land-based air power. All of Mindanao, as
well as the southern Visayas, now lay within easy range of enemy bombers, and the path stood open for the invasion of the Philippines.
The Palau and Morotai invasions were less than a week old when the enemy's carrier task forces gave a further and even more startling demonstration of their offensive power. This time they struck at Manila itself, the nervecenter of the Japanese military command and communications network for the entire Philippine area.
As in the earlier strikes on Mindanao and the Visayas, the presence of the enemy force was discovered too late to permit effective warning. A naval seaplane on patrol off the east coast of Luzon spotted the carrier group at 0905 on 21 September and immediately radioed a warning back to its base at Cavite, but by the time the alert was relayed to air bases and defense installations in the Manila area, the first wave of enemy planes was already overhead and launching the attack.34
Between 0930 and 1800, four waves totaling well over 400 aircraft swept in to bomb and strafe the harbor area and the airfields around Manila, including Clark and Nichols Fields. In the attacks on the harbor and on shipping along the west coast, 22 vessels aggregating over 100,000 gross tons were sunk or heavily damaged, while the raids on airfields caused considerable damage to grounded planes. Forty-two Zero fighters were able to get into the air to attack the enemy formations, but 20 of these failed to return.35
At 0610 the following day, 22 September, search planes discovered the enemy carrier groups still lurking off the coast of Luzon, and at 0730 a hit-and-run attack was carried out by 27 Japanese aircraft, with reported bomb hits on two carriers and one cruiser. Enemy planes nevertheless renewed their attacks on the Manila area between 0740 and 0950, inflicting further damage in the harbor sector. Naval air units at Legaspi attempted to carry out a second attack on the enemy carriers during the late afternoon, but the attack force of 19 planes failed to locate the carrier groups.36
The extension of the enemy's carrier-borne air offensive to Luzon, coupled with the amphibious moves to Palau and Morotai, left scant doubt in the minds of both the Army and Navy Sections of Imperial General Headquarters that Allied strategy aimed at launching the invasion of the Philippines at an early date. The High Command still considered it premature to order outright activation of Sho Operation No. 1, under consideration since 19 September, but it decided that operational preparations must be pushed with the utmost speed on the assumption that the Philippines would be the decisive battle theater. Accordingly, on 21 September, the Navy Section of Imperial General Headquarters issued a directive which stated:37
The Navy directive was followed on 22 September by an Imperial General Headquar
Further implementing this decision, the Army Section of Imperial General Headquarters ordered the 1st Division, hitherto scheduled under the Sho-Go plans to be held at Shanghai as strategic reserve until the activation of actual decisive battle operations in one of the Sho areas, to move immediately to the Philippines. Plans were also made to assign ten surface Raiding Regiments to the Philippine area.40
With respect to Southern Army's request for authorization to employ the main strength of the Fourth Air Army against raiding enemy carrier forces, Imperial General Headquarters demurred on the ground that such action would probably entail losses of aircraft and pilots incommensurate with the amount of damage which could be inflicted on the enemy. Authorization was granted, however, to carry out hit-and-run attacks with small elements whenever the situation appeared especially favorable for such operations.41
On 22 September Imperial General Headquarters also acted to implement plans for the reinforcement of the Fourth Air Army. The 16th Air Brigade (51st and 52d Fighter Regiments) was ordered to proceed to the Philippines at once, and the 12th Air Brigade (1st, 11th and 22d Fighter Regiments) was directed to prepare for subsequent movement upon the activation of Sho No. 1. In addition, three more fighter regiments, one light bomber regiment, three heavy bomber regiments and one reconnaissance regiment were allocated to Fourth Air Army, to advance to the Philippines upon the activation of Sho No. 1.42 On 11 October, a further order activated the 30th
Fighter Group headquarters to command the 12th and 16th Air Brigades, and another fighter regiment (200th) was added to its order of battle.43
In the Philippines, a sudden and marked increase in guerrilla activity during September heightened apprehension that an enemy attack was imminent. Small Japanese garrisons were attacked, pro-Japanese Filipinos molested and intimidated, and communications disrupted. In central Luzon there were indications that some guerrilla units were planning a move to the Lamon Bay area in order to be the first to cooperate with an American landing force, and on Negros and Panay guerrilla raids on Japanese airfields became boldly persistent. Fourteenth Area Army feared that, as soon as enemy forces landed, the guerrillas would not only give them direct assistance as scouts and guides, but seriously hamper Japanese operations by attacking rear communication lines.
The widespread destruction and panic caused by the enemy's carrier-borne air attacks had meanwhile resulted in outbreaks of civil disorder in many parts of the Philippines. On 22 September, therefore, martial law was proclaimed throughout the archipelago, and on the following day a state of war was declared against the United States and Great Britain.
On 24 September, only two days after the close of the aerial assault on Manila, enemy carrier planes struck again. Cebu was hit for the second time, and Legaspi and Coron Bay also underwent attacks which caused exceedingly heavy damage to naval and air installations.44 Six days later, on 30 September, enemy land bombers and fighters operating from the newlyconquered base on Morotai carried out a powerful attack on Balikpapan, in Dutch Borneo, demonstrating that Morotai-based aircraft could, at extreme range, cover not only the southern but the central Philippines.45
The deadly effectiveness of enemy air attacks had meanwhile led the Southern Army operations staff at Manila to question the feasibility of the basic strategy laid down by Imperial General Headquarters for the defense of the Philippines. Under the Sho-Go plans, only the sea and air forces were to wage decisive battle in the central or southern Philippines. The ground forces were to hold their main strength on Luzon, fighting only a delaying action in the central or southern Philippines if the enemy first landed there.
The Southern Army staff, however, reached the conclusion that it was unrealistic to prescribe separate decisive battle areas for the air-sea and the ground forces.46 This conclusion rested on the argument that it would become impossible to conduct decisive ground operations on Luzon once the enemy had acquired bases in the central and southern Philippines,
enabling the joint use of land and carrier-based air in massive support of invasion operations farther north. Therefore, concerted employment of air, sea and ground forces in defense of the central and southern Philippines appeared advisable.
Although this view was not officially transmitted to Tokyo, the Army High Command was aware of the trend of thinking in Southern Army headquarters. At this stage, however, it did not consider that the fundamental situation on which the original operational plan was based had undergone any radical change. On 26 September General Tomoyuki Yamashita, commander of the First Area Army in Manchuria, was transferred by Imperial General Headquarters order to command of the Fourteenth Area Army, replacing Lt. Gen. Kuroda. Stopping in Tokyo for consultation en route to his new command, General Yamashita was explicitly informed that the Army High Command still intended the decisive ground battle in the Philippines to be waged on Luzon, and that preparations should be made on this basis.47
The basic policy governing ground operations under the Sho No. 1 plan thus remained unchanged. On 6 October General Yamashita arrived in Manila to assume command of Fourteenth Area Army forces and prepare for the execution of this policy. On 11 October he summoned a conference of all subordinate commanders and notified them that the Area Army would "seek decisive battle on Luzon", while in the central and southern Philippines its objective would be to delay the enemy's advance and prevent his acquisition of naval and air bases.48
General Yamashita had barely set his shoulder to the task of completing preparations for a battle of decision on Luzon when the sudden appearance of powerful enemy naval task forces in the Nansei (Ryukyu) Islands area, less than 400 miles from the coast of southern Kyushu, set in train a series of events and last-minute changes in plan which exerted a fateful influence on the subsequent operations in defense of the Philippines.
The first indication that an enemy naval force might be operating near the Ryukyus was received on the morning of 9 October, when a navy plane on patrol between the Ryukyus and Bonins suddenly ceased radio communication with its base at Kanoya, on Kyushu, and subsequently failed to return. Second Air Fleet and Army and Navy forces in the Kyushu-Ryukyus-Formosa area went on the alert. They did not have long to wait, for at 0640 on 10 October enemy carrier planes launched a massive air assault on Okinawa and several other islands in the Nansei group.49
It was evident that the enemy, emboldened by his successful air strikes against the Philippines, had now sent his carrier task forces to attack targets on the very threshold of the Japanese home islands. Since early air reconnaissance established that these forces were
not accompanied by an invasion convoy of transports,50 the situation did not for the moment appear to be one which called for the immediate and full activation by Imperial General Headquarters of the Sho-Go plans. However, the Navy considered that decisive action by its own air forces was imperative.
The opening of the attack on the Ryukyus found Admiral Soemu Toyoda, Commander-inChief of the Combined Fleet, at Shinchiku, northern Formosa, on his way back to Tokyo from a command inspection trip to the Philippines. This had a vital effect on subsequent events, for it meant not only that Admiral Toyoda's decisions were psychologically influenced by his presence virtually on the front line of battle, but that full, direct consultation with the Navy High Command was rendered impossible. During the ensuing action, Admiral Toyoda, while delegating the power to make minor decisions to his Chief of Staff in Tokyo, actually directed operations from Formosa, issuing some orders direct and others through Combined Fleet headquarters in Tokyo.
To Admiral Toyoda, it seemed that the enemy, by sending his carrier forces into the northern Philippine Sea within striking range of the major concentrations of Japanese landbased air strength, had presented an opportunity that might never arise again, to deal the enemy fleet a crippling blow and disrupt the entire Allied invasion timetable. He therefore decided to gamble all available naval air strength in a determined effort to destroy the enemy carrier forces.
This meant a sharp divergence from the tactical concepts which formed the basis of the original Sho-Go plans. The central idea of those plans was to husband air, sea and ground strength until a major enemy invasion attempt against any of the areas constituting Japan's inner defense line, and then to commit all forces in decisive battle. Accordingly, while the use of minor elements of naval air strength against raiding enemy task forces prior to an invasion was authorized, commitment of the main strength of both Army and Navy air forces was to await Imperial General Headquarters decision activating one of the Sho operations.51
Actually, experience in the earlier Philippine strikes had shown that passive tactics against enemy task force raids were of doubtful effectiveness in conserving air strength. Moreover, discussions between the Navy's top operational commanders and the Naval General Staff had emphasized the impossibility under all circumstances of rigidly adhering to the Sho-Go plans with regard to air action against enemy task forces, and had resulted in agreement that a large measure off discretion must be left to the Combined Fleet command52 to determine the opportune moment for committing the naval air strength. Now, that moment appeared to be at hand.
Admiral Toyoda promptly decided to remain
on Formosa and assume personal direction of battle operations. At 0925 on 10 October, approximately three hours after the start of the enemy air assault on the Ryukyus, Combined Fleet headquarters in Tokyo, acting at Admiral Toyoda's direction, alerted all naval land-based air forces for Sho Operation No. 2. At 1214 the same day Admiral Toyoda, by order from Shinchiku, extended the alert to include Sho No. 1 as well.53
On 11 October the enemy carrier groups turned south to effect small-scale reconnaissance raids over the Aparri area, on northern Luzon. The following day, however, the air offensive was resumed in full force, this time against Formosa and adjacent islands. Admiral Toyoda now decided that it was time to strike. Again acting through Combined Fleet headquarters in Tokyo, he ordered the naval base air forces, at 1030 on 12 October, to execute Sho Operations Nos. 1 and 2, with the objective of destroying the enemy carrier forces in the northern Philippine Sea.54
Vice Adm. Shigeru Fukudome's Second Air Fleet, main strength of which was still deployed at bases in southern Kyushu,55 immediately prepared to attack. Meanwhile, to throw as many aircraft as possible into the battle, Combined Fleet headquarters in Tokyo ordered Vice Adm. Ozawa, First Mobile Fleet Commander, to release the newly-reconstituted flying groups of the 3d and 4th Carrier Divisions, which had not yet completed their combat training in the Inland Sea, to temporary command of the Second Air Fleet. These groups were immediately ordered to bases in southern Kyushu and the Nansei Islands to operate with the land-based air forces.
The first attack on the enemy carrier groups, three of which were now reported operating off the east coast of Formosa, was carried out between 1900 and 2020 on 12 October. Taking off from Kanoya air base,56 planes of the "T" Attack Force struck at the enemy within the perimeter of a sudden typhoon and then put down on Formosan bases. The pilots reported four enemy carriers sunk, and ten other major units set afire. Meanwhile, a separate force of 45 torpedo planes and Army TypeIV torpedo-bombers57 sortied from bases on Okinawa and carried out an attack, in which two unidentified fleet units were reported set a flame.58
Despite these reported successes, the enemy carrier forces renewed their assault on Formosa on 13 October, sending over a total of about 600 aircraft during the day. Damage in these raids was light, and the "T" Attack Force sortied from Kanoya late in the afternoon to strike back. Locating two enemy carrier groups southwest of Ishigaki Island, in the southern Ryukyus, the attack formation of 32 planes struck at dusk, reporting four ships sunk, of which two were carriers, and a third carrier left in flames.59
On the basis of the reported results of the attacks thus far, it appeared that at least one segment of the enemy task forces had been decisively crushed. This estimate was seemingly confirmed by the fact that carrier-plane raids on Formosa were resumed on a sharply reduced scale at 0700 on 14 October and ceased completely at 0930. It appeared that the enemy forces had initiated a retirement to the southeast.
Complete victory now appeared almost within grasp. To accomplish the total destruction of the damaged and withdrawing enemy, the Second Air Fleet ordered its entire strength of 450 planes to sortie from southern Kyushu.
Admiral Toyoda ordered the Second Striking Force under Vice Adm. Kiyohide Shima to sail from the Inland Sea and sweep the waters east of Formosa to mop up remnants of the reportedly crippled enemy task forces.60
On the afternoon of 14 October, 100 B-29 bombers evidently operating from China struck at Formosa in what was believed to be a covering operation for the retirement of the enemy fleet. Meanwhile, at 1525, the first wave of Second Air Fleet planes (124 aircraft) attacked an enemy group southwest of Ishigaki Island, claiming hits on one carrier and three cruisers. A second attack wave of 225 planes sortied but was unsuccessful in finding the enemy. The third, striking after nightfall with 70 aircraft, including Army torpedo bombers, claimed two carriers, one battleship and one heavy cruiser sunk, and one small carrier, one battleship and one light cruiser set afire.61
Events on 15 October caused optimism to remain at a high pitch. Second Air Fleet search planes reported that one aircraft carrier and two battleships, all trailing oil slicks and without steerage way, were spotted off the coast of Formosa under guard of 11 destroyers.62 Admiral Toyoda ordered naval air units to continue the attack despite heavy plane losses. Meanwhile, the Second Striking Force was already racing south from the Inland Sea at high speed to assist the air forces in cleaning up the enemy remnants.
Farther south, an enemy task group, with four carriers still intact, appeared off the east coast of Luzon and at 1000 on 15 October sent off a force of 80 planes to attack Manila. In interception operations, Japanese fighters claimed 32 enemy aircraft shot down or damaged, while two separate attacks on the enemy task group by a total of 115 Army and Navy planes from Philippine bases were reported to have sunk one of the carriers and set afire the flight decks of two others.63
On 16 October regular morning search missions over the western Philippine Sea brought in disquieting reports that did not seem to tally with earlier claims of damage to the enemy forces. Three separate task groups with a total of 13 carriers were reported navigating in the area.64 Forces aggregating 247 naval aircraft immediately sortied from Okinawa, Formosa and Luzon to search for the enemy groups. These units swept wide areas of the Philippine Sea but only a small number of the planes found the carriers.
Despite the conflicting reports, Admiral Toyoda and the Navy High Command were still inclined to believe that the enemy was attempting to cover the retirement of badly damaged and disorganized carrier task forces. If it were true, however, that enemy strength in the area was still as large as indicated by the reconnaissance reports of 16 October, the Second Striking Force, then passing east of the Ryukyus, was sailing directly into an engagement in which it would be heavily outweighed. The Chief of Staff of Combined Fleet therefore radioed a suggestion to Vice Adm. Shima that he change course to the west, pass through the northern Nansei Islands, and run south through the East China Sea in order to stay out of range of Allied carrier planes. This was followed by an order from Admiral Toyoda directing Vice Adm Shima to prepare to sortie again into the Pacific and fight a night engagement if an enemy force of appropriate size presented itself. If no such opportunity arose, the Second Striking Force was to proceed to the Pescadores and await further orders.65
Final reconnaissance reports on 17 October confirmed that considerable enemy strength remained present in the waters east of Formosa and Luzon, but also indicated that substantial damage had been inflicted. Of four separate task groups spotted, one of about 20 ships, including three carriers and three battleships, was reported withdrawing eastward at a reduced speed of ten knots with one of the battleships under tow. This strongly suggested that the group was composed of damaged ships retiring from action. Orders to attack were immediately issued, but contact was subsequently lost and the attacks could not be carried out.66
The Formosa air battle had now ended, and the Navy High Command undertook to assess the damage done to the enemy's carrier fleet. The necessity of avoiding any exaggeration of enemy losses was clearly recognized because of the importance to future operational planning. Combined Fleet staff officers thoroughly studied and sifted the action reports of the combat flying units. Although these reports were considered of dubious reliability, Second Air Fleet strongly insisted upon their accuracy, and in the absence of adequate post-attack reconnaissance, the Navy Section of Imperial General Headquarters had no choice but to base its assessment on the reports at hand. Enemy losses were finally listed as follows:67
These results, officially accepted and announced, added up to the most phenomenal success achieved by the Japanese Navy since the attack on Pearl Harbor. The nation was swept by a sudden wave of exhilaration which dispelled overnight the growing pessimism over the unfavorable trend of the war. Mass celebrations were held in many cities throughout the country, and government spokesmen proclaimed that "victory is within our grasp!" All Army and Navy units concerned were honored by the issuance of an Imperial Rescript.
However, while the nation thrilled to a victory which events soon proved to be a bitter illusion, the situation brought about by the Formosa air battle was actually fraught with potential disaster. The battle had cost the air forces 312 planes of all types, a level of losses which they could ill afford to sustain. The Second Air Fleet, comprising the main strength of the Navy's base air forces, had lost 50 per cent of its strength and was reduced to 230 operational aircraft.68 The First Air Fleet and Fourth Air Army in the Philippines were left with a combined operational strength of only a little over 100 aircraft.69 Of 143 carrier planes used to reinforce the Second Air Fleet, about one-third, with their flight crews, had been lost.70
The losses in carrier aircraft and flying personnel meant further delay in remanning the 3d and 4th Carrier Divisions, which Admiral Toyoda had hoped to send south to join the First Striking Force, thus providing it with desperately needed air striking elements.71 Moreover, the Second Striking Force, scheduled under the Sho-Go plans to operate as a vanguard to Vice Adm. Ozawa's Task Force Main Body, was now far from its base and had consumed tons of precious fuel in a fruitless operation. It was hoped that the damage inflicted on the enemy's carrier forces would slow up his invasion schedule long enough to permit the replenishment of aircraft losses and the redeployment of the surface forces. However, this hope was to prove vain.
The credence temporarily placed in the Navy's claims regarding the Formosa air battle also paved the way for a momentous change in plans regarding decisive ground operations in the Philippines. On the basis of the results officially claimed by the Navy for the Formosa Air Battle, it appeared likely that an enemy invasion of the Philippines would be delayed, or if undertaken soon, would be unsupported by strong carrier forces. Consequently, the Army Section of Imperial General Headquarters now became more favorably inclined toward modifying the Sho-Go plans along the lines of Southern Army thinking. However, there seemed to be ample time to study the matter in detail before reaching a final decision.72
That decision was still pending on 17 October, when the American invasion of the Philippines began in earnest.