By the first part of November 1944, the Fourteenth Area Army command was already convinced that the loss of Leyte could not be averted.1 Closely watching the unfavorable development of the struggle for this strategic island, General Yamashita and his staff concluded that enemy control of Leyte would be firmly established before mid-December, and that General MacArthur's forces would then be ready to launch the next move in the planned conquest of the Philippines.
The question of what this move would be was given serious study. Although a direct jump from Leyte to Luzon was not ruled out,2 the Area Army command considered it more probable that General MacArthur would preface his assault against Luzon by an intermediate operation in the central Philippines. The objective of this operation, it was surmised, would be to acquire advance air bases covering the most direct route of approach to the west coast of Luzon via the Sulu Sea.3
In the opinion of General Yamashita's staff, the enemy would probably seek such bases in the western Visayas. The Iloilo sector of Panay was considered a highly probable target of invasion because its coastline was suited for amphibious landing operations and because well-developed airfields already existed there. Cebu and Negros were rated secondary possibilities. Mindoro, although situated in greater proximity to the anticipated landing areas on central Luzon, received almost no consideration since it possessed relatively few favorable sites for the construction of operational airfields.4
Already short of troops for the defense of Luzon itself, Fourteenth Area Army could not contemplate serious resistance to a move into the western Visayas. It was therefore expected that the enemy would rapidly achieve his preliminary objectives and at the same time complete the build-up of his forces for the final blow against Luzon. This assault, it was estimated, would come around 7-10 January and would involve a total enemy strength of more than ten divisions. The main landing was expected either at Lingayen Gulf or in the Batangas area, with possible secondary landings at one or more of several points-Aparri on the north, Lamon Bay on the east, and Legaspi on the south. Airborne landings at key positions on the central Luzon plain were also considered probable.5
In the light of this assessment of enemy plans and capabilities, General Yamashita felt that it was imperative to stop diverting troops to Leyte immediately in order to reserve full strength, including all reinforcements either already allocated or promised to Fourteenth Area Army, for the defense of Luzon. This View was strongly pressed upon Southern Army between 7 and 10 November. On 11 Novem ber, however, Field Marshal Terauchi bluntly informed General Yamashita that the decisive battle on Leyte had to be continued at all costs, and that defensive preparations on Luzon might be expanded only insofar as they would not interfere with the execution of this policy.6
To comply with Field Marshal Terauchi's decision, Fourteenth Area Army promptly drew up a new reinforcement schedule. This called for the progressive commitment to Leyte of the 68th Brigade, the first elements of which had recently reached Luzon from Formosa,7 and the 23d and 10th Divisions, just allocated to the Area Army by Imperial General Headquarters. Since the Tokyo High Command currently was considering the allocation of only one additional division, the new schedule meant that the Area Army would divert the bulk of the reinforcements still to reach the theater to the Leyte battlefront.
General Yamashita. though keenly aware that execution of the reinforcement schedule would bar any attempt to revitalize the weakened defenses of Luzon, was prepared to carry it out as far as future developments allowed. At the same time, however, he could not ignore the fact that the rapid consolidation of the enemy's hold on Leyte and his ever-tightening control of the central Philippine sea lanes made it highly improbable that any reinforcements reaching Luzon later than the 68th Brigade could actually be moved to the battle zone. There was a strong possibility, therefore, that the 23d and 10th Divisions and any other forces later allocated would be available for the defense of Luzon. Again, however, this was contingent upon whether these forces could be successfully moved to Luzon from rear areas before the enemy invasion of Luzon was launched.
The existence of so many uncertain factors made it impossible at this stage to draw up any clear-cut tactical plan for the deployment of forces on Luzon. General Yamashita's staff nevertheless drafted a tentative outline of operational policies to meet the major situations which might arise. This outline, dated 14
November, was the first indication that the Area Army command was beginning to think in terms of a delaying defense of Luzon rather than a decisive engagement of forces. A summary of the essential points of the outline follows:8
In conformity with this rough outline of operational policies, General Yamashita immediately dispatched staff officers from Area
PLATE NO. 103
Army headquarters to carry out a preliminary survey of the three mountain districts designated as areas of final resistance. Late in November the transfer of essential base installations and reserve stores of ammunition and supplies to these areas began.10 To guard transport movements against increasingly troublesome attacks by guerrillas, the 2d Armored Division was ordered to augment its security measures protecting the central highway network leading out of the Manila area. Meanwhile, Area Army forces elsewhere on Luzon continued to strengthen their defense positions in preparation for the expected enemy assault.
Despite these preparatory steps for the defense of Luzon, the main effort of Fourteenth Area Army still remained centered on maintaining the flow of troops and supplies to Leyte in compliance with Field Marshal Terauchi's orders. To provide adequate reinforcements to the Thirty-fifth Army before its resistance collapsed entirely, General Yamashita was obliged to weaken still further the forces reserved for the defense of Luzon. Early in December, the 380th Independent Infantry Battalion of the 58th Independent Mixed Brigade was released to reinforce the 68th Brigade upon its final embarkation for Leyte. On 9 December the 5th Infantry Regiment of the 8th Division was shipped to northwestern Leyte in a last effort to prevent enemy capture of the Ormoc plain.
Of the five full divisions and two mixed brigades which had been present on Luzon and adjoining islands at the beginning of the Leyte operation, only two inferior divisions, the 103d and 105th, and one mixed brigade still remained unweakened. The Area Army had diverted to Leyte almost all of the 26th Division and varying portions of the 2d Armored Division, 8th Division, and 58th Independent Mixed Brigade.
The remainder of these original forces was thinly distributed over Luzon and adjoining islands. (Plate No. 103 On the Batan and Babuyan Islands to the north of Luzon was the 61st Independent Mixed Brigade. The 103d Division was spread over northern Luzon, with its main strength around Aparri. The 58th Independent Mixed Brigade, reinforced by the 12th Surface Raiding Regiment with about 80 special-attack boats, guarded the vital coastal sector of Lingayen Gulf.11
The 2d Armored Division, the only large mobile force under Fourteenth Area Army control, had the bulk of its forces concentrated in the San Miguel-Cabanatuan sector to protect the highway system of north-central Luzon. One tank regiment of the division was stationed south of Laguna de Bay, in Batangas Province, to act as a spearhead force in the event of an enemy landing in that area.
The Manila Defense Force covered the Manila area and Bataan Peninsula.12 As of 13 December, this force had a combat strength
of four provisional infantry battalions and five infantry companies. One provisional infantry battalion was stationed on Bataan Peninsula, one company each at Olongapo, Bagac, and Mariveles.
The 8th Division, less elements transferred to Leyte, continued to keep its main strength disposed at key points in Batangas Province. The division also had under its command the 2d Surface Raiding Force with about 220 special-attack boats, based in Batangas and Balayan Bays. Mindoro Island was included in the divisional area of responsibility, but because of inadequate troop strength and the belief that an enemy landing there was unlikely, only a small security force of two provisional infantry companies under command of the 17th Infantry Regiment was stationed on the island.13
Defense of the Baler and Dingalan Bay sectors, on the east central coast of Luzon, was charged to the Tsuda Detachment, composed of the 11th Independent Infantry Regiment (reinf.) of the 26th Division. The 82d In fantry Brigade of the 105th Division, organized as the Kawashima Detachment and operating under direct Area Army command, occupied positions in the Lamon Bay area, farther to the south, where it was reinforced by the 1st Surface Raiding Force with about 180 special attack craft. The 105th Division, reinforced by the 26th Independent Mixed Regiment (less 1st Battalion on northwest Samar), was deployed on southern Luzon, principally in the Legaspi area and at Naga.14
It was not until December that elements of the additional divisions allocated by Imperial General Headquarters began to arrive on Luzon. The first echelon of the 23d Division debarked at San Fernando, on northwestern Luzon, on 2 December and began a period of regrouping and re-equipment necessitated by severe losses inflicted by enemy submarines while the convoy was en route from Formosa.15 On 10 December the first echelon of the 10th Division arrived at Manila, followed on the next day by the second echelon of the 23d Division.16 No elements of the 19th Division, newly assigned to Fourteenth Area Army on 20 November, had yet reached Luzon.
Immediately upon the arrival of its first echelon, the 10th Division was ordered by Fourteenth Area Army to organize a force to execute a counterlanding on northern Leyte under the Ketsu Operation plan.17 This force, designated the Nagayoshi Detachment, was
organized from the 39th Infantry and supporting troops. Although the detachment immediately began preparing to re-embark, tightening enemy control of the central Philippine sea routes made it virtually certain that the rest of the 10th Division and all of the 23d Division would never move to Leyte as scheduled in mid-November. The Area Army therefore began fitting these units into its plans for the defense of Luzon. The first step was an order to the 23d Division on 8 December, directing it to move to the San Jose and Umingan sectors and organize defense positions. One infantry battalion was to be released by the division to reinforce the 58th Independent Mixed Brigade in the Lingayen sector.18
In addition to the Army forces on Luzon, approximately 25,000 naval ground combat troops were distributed in the Manila Bay area, at Clark Field, and at Legaspi.19 These troops, with the exception of the naval garrison unit stationed at Clark Field, were under command of the 31st Special Base Force headquarters in Manila, which in turn was controlled by Southwest Area Fleet, the top theater naval command. The Clark Field unit was commanded by the First Combined Base Air Force.
The numerical weakness of the ground combat forces was aggravated by a dangerously low level of ammunition and food reserves. A large proportion of the stores built up on Luzon for the Sho-Go Operation had been drained off to supply the Thirty-fifth Army on Leyte.20 Enemy submarine activity against Japanese supply lines leading to Luzon made it increasingly difficult to replace the amounts expended.21 As of mid-December, each division on Luzon had on hand 1,600/2,000 tons of ammunition, in addition to an Area Army reserve of not more than 1,000 tons per division, mostly stored in the Manila area.22 With the arrival of additional troops, the shortage of available reserves became even more accentuated.
The situation in regard to air strength was equally ominous. Despite an increased flow of air replacements from the Homeland during November, constant enemy attacks on Japanese air bases and heavy losses incurred in supporting the Leyte operation had gradually whittled down the army and navy air forces in the theater. On the eve of the Mindoro invasion, they could muster a combined operational strength of only about 230 aircraft of all types. The Fourth Air Army, on 9 December, had a total of 133 operational planes, divided between bases on Luzon and in the Bacolod area of Negros.23 On 14 December, the Navy's First Combined Base Air Force, including the First and Second Air Fleets, was down to about 100
PLATE NO. 104
aircraft, based mainly at Clark Field on Luzon.24
The condition of the naval surface forces also precluded strong fleet intervention against an enemy move into the northern Philippines. Vice Adm. Shima's Second Striking Force, which had retired from Brunei to Lingga in November after the Battle for Leyte Gulf, was the only surface force of any consequence remaining in the southern area. Its operational strength on 13 December comprised only the two hybrid battleship-carriers Ise and Hyuga, three cruisers and three destroyers.25 All other major fleet units were in the shelter of Japanese home waters. Of these, only three battleships, one cruiser and five first-line destroyers were fit for action. All six existing carriers were immobilized by lack of air complements.26
Naval units actually present in Philippine waters were limited to small craft. Five escort destroyers still remained in Manila Bay on 13 December, but the initiation of heavy enemy air attacks on the Manila area led Southwest Area Fleet on the 14th to order them to Camranh Bay in French Indo-China, and to Singapore. The withdrawal of these units left in the Philippines a total of two submarine chasers, 19 PT boats, ten midget submarines, and about 180 naval special-attack craft. The last were assembled mainly in Manila Bay.27
Such was the over-all situation of the Japanese ground, air, and sea forces available for the defense of the northern Philippines when the approaching end of Thirty-fifth Army resistance on Leyte foreshadowed the launching of General MacArthur's next assault. The Fourteenth Area Army command had estimated correctly the time of this assault, but the enemy again struck at a point where invasion was least expected.
First warning that an enemy amphibious force was on the move came at 0900 on 13 December. An Army reconnaissance plane radioed back to its base that a formation of about 80 ships was moving westward through the Mindanao Sea 45 miles north of Cagayan. Further air searches confirmed this sighting, and at 1710 three naval Kamikaze aircraft with fighter escort took off from Cebu to attack the formation as it passed south of Negros Island. Two cruisers were reported set afire by suicide crashes.28 Army special-attack planes launched additional strikes during the day and claimed hits on one naval unit and one transport.29
Although the size and composition of the enemy force left no doubt that an amphibious landing was intended, the target remained uncertain. The position of the convoy by nightfall on the 13th had eliminated Cebu as a possible objective, but it was still expected that the landing would be made in the western Visayas, either on Negros or on Panay. Ground forces throughout the threatened area were alerted. On Luzon, the Fourth Air Army and First Combined Base Air Force commands prepared to throw all available strength into an aerial assault on the invasion convoy at dawn of the following day.30 Southwest Area Fleet simultaneously ordered the Second Striking Force to move up from Lingga to Camranh Bay in preparation for a possible sortie.
To pinpoint the convoy for the planned air attack, search planes took off before daybreak on 14 December and combed the coastal waters off Panay and Negros, expecting to find the enemy already starting landing operations. Actually, the invasion force was steaming on northward through the Sulu Sea, and the search failed to re-establish contact. The main attack groups poised at Clark Field nevertheless took off at 0715 to make a sweep of the general target area. Flying south over Batangas, they ran headlong into a formation of enemy carrier-borne fighters, and only part of the force was able to elude pursuit and continue the mission. Most of these planes failed to locate the enemy convoy, and results were not clear.
Further attack operations from Luzon bases were interdicted throughout the day by heavy and sustained enemy carrier-plane raids involving an estimated total of 560 sorties. In the meantime, however, Army aircraft based at Bacolod had picked up the invasion fleet off the southwestern tip of Panay at 0745. Intermittent strikes were flown by small formations of planes from Negros bases during the morning and afternoon, with undetermined results.31 At 1330 the enemy force was reported still heading northwest through the Sulu Sea at a speed of 15 knots.
By late afternoon of the 14th the location of the convoy in the southern waters of Mindoro Strait made it clear that the objective lay beyond the western Visayas. For the first time Fourteenth Area Army estimated that the landing would take place on Mindoro and ordered the 8th Division to alert its outposts there.32 It was also a serious possibility,, however, that the enemy might strike directly at Luzon. General Yamashita therefore issued a warning to Area Army forces throughout central Luzon. As a further precaution, the Nagayoshi Detachment, which was awaiting shipment to Leyte, and the 71st Infantry Regiment of the 23d Division, which had just reached Manila, were ordered to deploy immediately to Bataan Peninsula and Batangas, respectively, to meet potential enemy landings in those sectors.33
The Navy and air commands in Manila saw much greater probability of a landing on Luzon than on Mindoro. They therefore directed all subordinate units and installations to prepare for action against both enemy amphibious forces and possible airborne attack groups.34
Developments early on 15 December proved the Area Army's eleventh-hour estimate correct. At 0530 a navy plane reported that the invasion force was standing at anchor off San Jose, on the southwest coast of Mindoro, apparently starting to put troops ashore from 30 transports. An element of the 1st Provisional Infantry Company, 359th Independent Infantry Battalion, and a small number of naval seaplane base personnel were the only Japanese forces present in the area. Incapable of offering any serious resistance to the enemy landing, which was estimated to involve an entire division, these forces hastily withdrew inland along the trail toward Bulalacao, on the southeast coast of the island.35 (Plate No. 105)
Air opposition to the landing during 15 December was restricted by a renewal of heavy enemy carrier-plane raids on Luzon bases, as well as by cumulative operational losses sustained during the two preceding days. Before the enemy raids began, however, a group of 13 navy suicide planes took off from Clark Field and penetrated to the landing area without fighter escort to execute a determined attack. Only two planes returned, reporting three transports sunk and several other ships damaged. A further sortie against the landing point was attempted in the afternoon by Cebu-based naval aircraft but was unsuccessful.36
The enemy's new invasion move had already set in motion a vital exchange of communications between General Yamashita and Field Marshal Terauchi at Saigon. Early on 1 4 December, less than twenty-four hours after the enemy convoy was first sighted, the Fourteenth Area Army Commander had radioed to Field Marshal Terauchi recommendations for a basic modification of operational policy for the Philippines. These recommendations were premised explicitly on the assumption that the enemy was about to invade Negros or Panay, in the western Visayas. They provided that further operations in the Thirty-fifth Army zone, including both Leyte and the Visayas, should be limited to delaying actions by the forces
PLATE NO. 105
already present, and that the Area Army should immediately concentrate all effort on preparing for the final defense of Luzon.37
When the enemy landed at Mindoro instead of in the western Visayas, General Yamashita did not withdraw his recommendations of the 14th. Mindoro was not under Thirty-fifth Army but within the Area Army's zone of direct responsibility. The enemy landing therefore created a situation not specifically covered in the recommendations. Despite this fact, General Yamashita felt that the broad policies he had urged in his message to Southern Army needed no basic revision.
Even more clearly than if the Visayas had been invaded, the establishment of an enemy foothold on southwestern Mindoro meant the forced termination of all assistance from Luzon to Thirty-fifth Army forces in the central and southern Philippines. Mindoro was scarcely 150 miles from Manila Bay, the nerve-center of supply and reinforcement operations for the entire Philippine area. Enemy air power based there would completely block all southward movement. Just as clearly, the enemy move forewarned that the final advance on Luzon would be launched at an early date. This made it imperative to complete defense preparations with all possible speed.
General Yamashita, however, still had to decide the immediate question of what to do about the situation on Mindoro. This issue was hastily studied on 15 December, immediately upon confirmation of the enemy landing. Although the invaded area was dangerously close to Luzon, the Area Army staff decided that any attempt to bolster the meager forces on Mindoro was not feasible. Enemy control of the air and sea, the impossibility of amassing enough shipping to move an effective force, and the delay which a diversion of troop strength from Luzon would impose upon preparations for defense of the main island ruled out any attempt at sending reinforcements.38
At Saigon, the policy recommendations transmitted by General Yamashita on 14 December were being studied by Field Marshal Terauchi when another dispatch from Manila, dated the 15th, reported the enemy landing on Mindoro. It was clear from this dispatch that the Area Army had no intention of undertaking aggressive action. Field Marshal Terauchi, however, took an opposite view. In his opinion, the acquisition of advanced bases on Mindoro would so clinch enemy air domination to the north that the later defense of Luzon would become impossible. He therefore dispatched a radio message to Fourteenth Area Army on the same day, strongly urging a counterlanding. On 16 December Lt. Gen. Jo Iimura, Southern Army Chief of Staff, departed for Manila to consult with the Area Army on all questions of future strategy.
Reaching Manila on 17 December, Lt. Gen. Iimura immediately conferred with Lt. Gen. Akira Muto, Area Army Chief of Staff. The latter explained in detail General Yamashita's strategic plans, and Lt. Gen. Iimura, convinced that these plans were sound, sent a radio to Field Marshal Terauchi on 18 December advising blanket approval of the Area Army Commander's proposals of the 14th. He further urged that full discretion be left to the theater command in tactical matters. Before this message reached Saigon, Field Marshal Terauchi had again radioed to Manila reiterating the need of speedy action to counter the enemy landing on Mindoro. On 19 December, how ever, a further communication from Saigon transmitted concurrence in Lt. Gen. Iimura's
Despite Southern Army's final agreement to give Fourteenth Area Army full latitude in tactical decisions, the question of a counterl anding on Mindoro continued to be debated in Manila under pressure from other quarters. Southwest Area Fleet was already making independent plans for a hit-and-run surface force attack on enemy invasion ships off San Jose. On 20 December, just as final orders were sent to Vice Adm. Shima's Second Striking Force at Camranh Bay to execute this attack, the Area Fleet received instructions from Combined Fleet to discuss the possibilities of a full-scale counterlanding with Fourteenth Area Army.39 Both Fourth Air Army and the First Combined Base Air Force strongly supported a counterlanding because the advance of enemy land-based air power to Mindoro would virtually terminate operations from major Japanese bases on central Luzon.
Imperial General Headquarters in Tokyo had also studied the strategic implications of the Mindoro invasion and decided upon a gen eral revision of the Sho No. 1 Operation plan to meet the new situation in the Philippines. This revision was embodied in two draft outlines dated 18 December, the first jointly concurred in by the Army and Navy Sections, and the second drawn up by the Army Section operations staff. Although intended only as a basis for discussion with the theater command, both these documents contained specific provisos for action to prevent or at least impede enemy utilization of air bases on Mindoro.40
Immediately after the formulation of these tentative policy directives, the Army Section of Imperial General Headquarters dispatched a staff mission from Tokyo headed by Lt. Gen. Shuichi Miyazaki, Chief of First Bureau (Operations), to confer with Lt. Gen. Iimura and General Yamashita's command regarding future strategy in the Philippines. Reaching Manila on 21 December, Lt. Gen. Miyazaki began a series of staff consultations in which the ques tion of bolstering the defense of Mindoro again arose. No attempt was made to force any definite course of action upon the Area Army, but Lt. Gen. Miyazaki indicated that Imperial General Headquarters shared Southern Army's opinion that all possible steps should be taken to hinder enemy utilization of air bases on Mindoro. The Area Army therefore agreed on 23 December to re-examine the possibility of
PLATE NO. 106
dispatching minor troop reinforcements.41
The result of this re-examination was a half-hearted compromise. The Area Army staff adamantly maintained that it would be impossible to move any sizeable forces to Mindoro but agreed to dispatch a small raiding unit to hamper enemy development of airfields in the San Jose area. On or about 24 December, an order was issued to the 8th Division to organize a task unit for this mission as soon as possible.
While the counterlanding issue was being thrashed out in Manila, Vice Adm. Shima's Second Striking Force at Camranh Bay had completed preparations for the planned surface thrust at enemy invasion shipping in the San Jose area. On 24 December, a task group composed of the heavy cruiser Ashigara, one light cruiser, and six destroyers set out from Camranh Bay to execute the attack.42
As the task group neared Mindoro on the evening of the 26th, it was spotted by enemy aircraft. A severe air attack shortly thereafter sank one destroyer and inflicted minor damage on the Ashigara and two other ships. The force nevertheless continued toward the objective and at 2300 broke into the anchorage area. There it briefly shelled shore installations and launched torpedo attacks against enemy ships, four of which were claimed sunk. The task group withdrew at midnight without encountering surface opposition and headed back to Camranh Bay.43 This marked the last sortie by Japanese fleet units into Philippine waters.
On the same day that the naval attack was executed, a small ground raiding detachment organized by the 8th Division assembled at Batangas and prepared to embark for Mindoro.44 On 31 December the detachment finally moved by landing craft across the Verde Island Passage to Calapan, on northeastern Mindoro, and thence to Pinamalayan, where it arrived on 5 January. Three days later, just as the invasion of Luzon was beginning, the detachment encountered an enemy force advancing up Mindoro's east coast and was forced to sail back to Calapan. Although it later succeeded in moving to Mansalay, on the southeast coast of Mindoro, and then infiltrated overland toward San Jose, all attempts to raid enemy airfields were abortive.45
During the latter part of December and early January, the debilitated Army and Navy air forces based on Luzon and Negros also endeavored to impede the development of enemy bases on Mindoro by attacking resup ply convoys en route from Leyte and raiding airfields in the San Jose area.46 The air effort, however, was equally ineffectual in retarding the enemy's swift accomplishment of his objectives. By late December reconnaissance
reports indicated that at least two air bases had been completed and put into full operational use.
During the short breathing spell afforded by the Mindoro operation, Fourteenth Area Army poured its full effort into speeding final plans and preparations to meet the impending enemy onslaught against Luzon. The Area Army command now anticipated that the invasion would come between 10 and 20 January, with the main thrust directed either at the Batangas area or at Lingayen Gulf.47
Before formulating detailed plans, General Yamashita first had to decide the basic tactics to be employed in the defense of Luzon. When the tentative plans of mid-November were formulated, uncertainty as to the troop strength which would be available had made it impossible to foresee whether the Area Army would be capable of waging another decisive battle as on Leyte or whether it would be obliged to fall back upon defensive tactics calculated to delay the enemy and wear down his strength. At that period, however, General Yamashita had hoped that he would have adequate forces at his command to challenge the enemy in decisive battle.
By the time Mindoro was invaded, no such optimism remained. Although the Area Army could count upon employing all incom ing reinforcements for the defense of Luzon,48 shipping hazards and delays made it improbable that these forces would be assembled on Luzon in time to deploy for battle by the expected date of invasion. Moreover, in view of the steady decimation of the air forces, it was certain that operations would have to be conducted under a smothering blanket of enemy air power.
Under these circumstances, General Yamas hita feared that an all-out offensive effort in the initial phase of the battle for Luzon might result in the early destruction of his own forces. Coordinated delaying action, including local counteroffensives under favorable circumstances, seemed to assure better prospects of prolonged resistance. Such tactics would consume maximum enemy strength and gain precious time for the reinforcement of Japanese defenses on Formosa and the Ryukyus. The Area Army operations staff was therefore in structed to draw up final plans based on the concept of a protracted delaying action.49
On 19 December a general outline of operation was completed. Detailed appendices were issued the next day specifying the disposition, missions and command status of forces in two broad operational zones, one covering northern Luzon and the other, central and southern Luzon. These plans envisaged an initial effort by the forces defending coastal areas to inflict maximum losses upon the enemy at the time of landing. Delaying actions would then follow with the purpose of retarding capture of key inland communication points and airfields. The last phase would be a prolonged last-ditch stand in the three mountain regions previously designated as areas of final resistance. Commitment of the main Area Army forces in a large-scale offensive was not entirely excluded. Such action, however, would be undertaken only in an exceptionally favorable tactical situation. The general plan of operations was outlined as follows:50
PLATE NO. 107
The greater part of the Area Army was to be committed to the defense of the northern sector for two reasons: first, because of its strategic importance for the purpose of delaying subsequent enemy operations against Formosa and the Ryukyus; secondly, because its mountain fastnesses and few routes of entry from the central Luzon plain provided the most favorable tactical conditions for extended resistance. The plans of 19-20 December therefore shifted the center of gravity of Area Army troop dispositions to the north. The heaviest concentration of forces was to be disposed along the southern perimeter of the great northern defense sector, running from the eastern shore of Lingayen Gulf to the vicinity of Baler Bay. Southern Luzon was to be virtually stripped of troops in order to bolster the second largest concentration of forces in the mountains east of Manila. Planned dispositions and mission assignments of Area Army forces were as follows:51 (Plate No. 107)
Southern and Central Zone
Under the foregoing Area Army plans, airfield troops and base personnel of the Fourth Air Army and First Combined Base Air Force were to shoulder the responsibility of defending the Clark Field sector and the projected mountain strongpoint to the west. These forces were not under Fourteenth Area Army control. A draft agreement appended to the detailed operational plan for southern and central Luzon provided that these troops should come under the unified command of the ranking air commander in the Clark Field sector. However, Fourth Air Army, with Area Army assistance, was to plan and direct the construction of defense positions.56
The Area Army plans further envisaged immediate preparations for the transfer of General Yamashita's headquarters from Manila
to Baguio and the establishment of an Area Army command post at Ipo, northeast of Manila, to facilitate control of operations in the central and southern zone.
As the margin of time before General MacArthur's anticipated assault narrowed steadily, the Japanese forces on Luzon plunged into intense activity to implement the newly formulated battle plans. The Area Army accelerated the displacement of base installations and of munition and supplies not required in the first phase of operations into the three key defense areas. At the same time, the first troop movements required by the northern sector plans were begun.
Between 19 and 22 December, the main body of the 23d Division in the Umingan-San Jose area moved back to the division's newly-assigned sector of responsibility along Lingayen Gulf. Headquarters was established at Sison, five miles inland from the coast. Meanwhile, the 71st Infantry, which had been restored to division control on 18 December, moved north
from the Batangas area toward Lingayen.57 On 23 December the division third echelon from Formosa, made up of supporting elements, disembarked at San Fernando, in the northern part of the Lingayen section.58
The headquarters and first echelon elements of the 10th Division, less the Nagayoshi Detachment, had already moved north from Manila to occupy the San Jose sector vacated by the 23d Division. By 20 December, these elements were assembled at San Jose. Three days later the division second echelon reached Luzon from Formosa. The bulk of the troops disembarked at San Fernando and immediately prepared to move inland to join the division headquarters.59 As a result of a last-minute Area Army order, however, the major portion of the 10th Infantry Regiment was diverted to Aparri and attached to the 103d Division to reinforce the defenses of the Cagayan Valley.60
The 19th Division was now the only major reinforcement unit allocated to Fourteenth Area Army which had not yet reached Luzon. On 27 December, however, the main strength of the division finally arrived from Formosa, without enemy interference and disembarked at
PLATE NO. 108
San Fernando.61 The division immediately began hauling its equipment and supplies to an inland assembly area at Naguilian, southeast of San Fernando, preparatory to moving to its assigned positions in the San Leon sector on the south rear flank of the 23d Division.
Meanwhile, Fourteenth Area Army had reconsidered the problem of assisting the Fourth Air Army and First Combined Base Air Force units in the preparation of defenses in the Clark Field sector. It was originally intended to limit such assistance to the dispatch of staff officers as technical advisors. As a result of an on-the-spot survey, however, the Area Army decided that this would be insufficient and ordered the 2d Armored Division to send the main strength of the 2d Mobile Infantry Regiment, with a tank company attached, to the Clark Field area. This force arrived about 24 December and immediately began organizing defensive positions. Shortly thereafter, the 2d Glider Infantry Regiment and miscellaneous smaller units of the 1st Airborne Raiding Group, assigned to Fourth Air Army, landed at San Fernando and were ordered to proceed at once to the Clark Field sector.62 These were the last seaborne reinforcements to reach the Philippines.
In the central and southern zone, troop shifts to effect the new dispositions envisaged in the 19-20 December plans were not started until the last week in December. On the 23d, Fourteenth Area Army issued the first implementing order, which directed the 105th Division to begin transferring its main strength from the Bicol area to the sector just north of Laguna de Bay. Here it was to organize the southern flank of the key defense area east of Manila.63 Division elements remaining in the San Bernardino Strait and Legaspi sectors were formed into the Noguchi Detachment and placed under direct Area Army control.64
While the 105th Division was preparing to execute this order, the Area Army decided upon the significant modification of the 19-20 December plans. These plans had originally envisaged a gradual withdrawal of forces into the key mountain positions east of Manila, possibly continuing after the start of the enemy invasion. However, the serious dislocation of troop and supply transport by increasingly persistent enemy air attacks65 and guerrilla destruction created a danger that such movement might become impossible if delayed too long. General Yamashita therefore decided to concentrate maximum forces, in the area east of Manila with all possible speed.
To implement this decision, the Area Army on 27 December ordered the 8th Division to transfer its main strength, previously scheduled to occupy positions east and west of Lake Taal, to the area east of Manila. Effective 1 January, the division commander was to assume command of all Area Army forces on the southern half of Luzon below a line running roughly from the Manila area on the west to the Lamon Bay area on the east. These forces were designated the Shimbu Group. The Noguchi Detachment was released from its previously assigned mission of securing the San Bernard ino Strait area, and the Shimbu Group commander was authorized to move both this detachment and the Kawashima Force (Lamon Bay sector) toward the main concentration of forces in the area east of Manila.66
In accordance with the Area Army order, Lt. Gen. Shizuo Yokoyama, 8th Division commander, immediately ordered the main body of the division to concentrate at Ipo, Wawa and Antipolo. The 17th Infantry Regiment (less 3d Battalion, but with 3d Battalion, 31st Infantry, attached was simultaneously designated the Fuji Force and ordered to remain in the Batangas area to defend key points. On 1 January Lt. Gen. Yokoyama moved to Manila with his headquarters, there assuming command of the Shimbu Group. An order issued the next day to the forces newly placed under his control called for the following dispositions:67
When this order was issued, the assembly of the 105th Division in the Antipolo sector was already well under way, and the first elements of the 8th Division were arriving at their new positions at Ipo, Wawa and Antipolo. By 1 January also, the Kawashima Force and the major portion of the Manila Defense Force had completed necessary preparation and were ready to move to the Ipo and Wawa sectors, respectively.
General Yamashita at this time was directing battle preparations from the Area Army's southern command post at Ipo, where he and a skeleton operational staff had arrived from Manila on 26 December. Shortly after his arrival, he was notified by Southern Army that all Fourth Air Army forces in the Philippines would come under Area Army control beginning 1 January 1945. In preparation for this change, the Area Army on 29 December issued an order from Ipo specifying the missions of the Fourth Air Army. General objectives of the Air Army were stated in this order as follows:69
As soon as its control over the Army air forces became effective, the Area Army took further action to hasten the organization of ground defenses in the Clark Field sector. Lt. Gen. Yoshiharu Iwanaka, 2d Armored Division commander, was ordered to assume full responsibility for the execution of this mission and to coordinate the activities of the 2d Armored Division elements already in the Clark Field sector with those of the local Army and Navy airfield units. The dispatch of additional ground combat troops to the area, however, was not contemplated.
During the latter part of December, battle preparations proceeded with discouraging slowness. Overburdened transport facilities, enemy strafing and bombing attacks, guerrilla interference and an acute shortage of automotive fuel impeded progress in every direction. On the other hand, there were numerous indica tions that General MacArthur was virtually ready to strike. In the Batangas area, enemy air reconnaissance was conspicuously frequent, while the dropping of dummy parachutists and the activity of small surface craft along the coast also caused grave alarm in the 8th Division. Other reports indicated that guerrilla forces were beginning to assemble in the mountains east of Manila, and that enemy submarines were delivering arms to guerrillas in the Lamon Bay area.
The concentration of these activities in the south-central area of Luzon exerted a marked influence on the Area Army's estimate of the location of the enemy's main attack. After the first shock of the unexpected landing on Mindoro had passed, belief that Batangas would be the principal invasion point gradually diminished. Instead, there was an increasing tendency to believe that basic considerations of terrain and strategy would lead General MacArthur to land his main forces at Lingayen. The pronounced enemy activity in the Batangas and Manila areas, however, countered this tendency and made it impossible for the Area Army to arrive at any defi-
PLATE NO. 109
nite conclusion. As December ended, this uncertainty still prevailed.70
General Yamashita's tense and expectant forces were still racing against time to complete,their battle preparations when the first warnings came that the enemy was again on the move. At 1322 on 2 January, a naval lookout post on Surigao Strait reported that a long train of about 80 enemy ships, screened by destroyers, was moving through the strait into the Mindanao Sea. Other reports which followed immediately warned that large numbers of invasion craft were gathered in the Leyte, Palau and Marianas areas, and that enemy submarines had appeared in force off the west coast of Luzon.71
At first it was thought that the enemy convoy was merely a reinforcement and resupply group destined for Mindoro. On 3 January, however, developments began to point more conclusively toward a full-scale amphibious operation against Luzon. In the afternoon, just as the initially sighted enemy group passed into the Sulu Sea, a large enemy naval task force, including 12 escort carriers, four battleships and eight cruisers, was reported following in its wake through Surigao Strait. Another delayed report stated that an enemy transport convoy of 90 ships, under strong naval escort, had been spotted the previous day northwest of Palau, heading in the direction of Leyte Gulf.72
With such powerful enemy forces in motion, Southwest Area Fleet headquarters in Manila now considered an invasion of Luzon virtually certain. Area Army staff officers remaining in the Philippine capital took the same view. Their estimate of the situation was immediate- ly radioed to Baguio, where General Yama shita and part of his staff had proceeded the same day to effect the planned transfer of the Area Army headquarters.73 All forces on Luzon were promptly alerted for action.
Small numbers of aircraft had struck spasmodically at the enemy ships as they moved through the Mindanao Sea on 3 January. It was not until late afternoon of the 4th, however, that the first really determined and effective attacks were carried out by fighter-escorted suicide planes of the Fourth Air Army's 30th, Fighter Group. Sortieing from Clark Field, these planes struck leading elements of the invasion force off southwestern Mindoro and between the Cuyo Islands and Panay. Five planes were reported to have executed suicide crash attacks.74 (Plate No. 109
Air action was intensified on 5 January as the vanguard of the invasion armada continued on past Mindoro and sailed up the west coast of Luzon. Suicide and other aircraft of the First Combined Base Air Force joined army planes in launching a succession of fierce attacks in the late afternoon as the enemy
ships passed to the west of Manila Bay. Although extremely strong fighter opposition was encountered, returning aircraft reported a number of successful suicide hits on enemy vessels.75
By this time General Yamashita and his staff were firmly convinced that the enemy's ultimate destination was Lingayen Gulf. The forces in that area, caught with their dispositions for battle still incomplete, feverishly prepared to meet the impending onslaught. Lt. Gen. Muto, Area Army Chief of Staff, hastily inspected the 23d Division sector on the afternoon of the 5th and discovered that the division was organizing its main line of resistance so that it veered away from the coast at a point northeast of San Fabian and skirted the mountains along the northern edge of the central plain. From the point where the main line swerved eastward, a forward line of positions branched off southward to the Cabaruan Hills. This forward line was manned by relatively minor forces and was to be held only until enemy pressure became too severe. The defending elements were then to fall back on the main mountain positions. (Plate No. 110)
Lt. Gen. Muto considered these dispositions weak and inadequate. When he returned to Baguio late the same day, he urged the Area Army Commander to order the 23d Division to strengthen the forward positions on the south flank and make them part of the main line of resistance. Such an order was immediately issued although it was recognized that any major shift of troops strength could probably not be effected in time. It was hoped, nevertheless, that the order would spur the division to make a maximum effort in defense of the forward positions.76 As a further step toward strengthening the sector, General Yamashita ordered the 2d Armored Division to send a detachment to Urdaneta, just northeast of the Cabaruan Hills.77
Developments on the morning of 6 January left no doubt about the enemy's intentions. Dawn of that day found leading elements of the invasion force entering Lingayen Gulf, and shortly thereafter naval units began a preliminary bombardment of the shore defenses, concentrating primarily on targets in the San Fernando area. Simultaneously, enemy land-based and carrier aircraft launched attacks on the Manila and Clark Field areas in an effort to neutralize air opposition to the landing operation.78
Despite these air assaults, Fourth Air Army and the First Combined Base Air Force threw every available plane into a daylong series of strikes both at the invasion ships in Lingayen Gulf and at follow-up elements along the route to the invasion area. In three major attacks on the Lingayen Gulf and San Fernando areas by Kamikaze of the First Combined Base Air Force, over fifteen suicide hits were reported,
PLATE NO. 110
while three other hits were claimed for suicide planes of the Fourth Air Army. Naval Kamikaze also struck at a follow-up group off Iba, with reported hits on five enemy ships.79
The heavy bombardment of the San Fernando sector on the 6th aroused great anxiety in General Yamashita's headquarters. An enemy landing in that sector would fall north of the main positions of the 58th Independent Mixed Brigade and create serious danger of a thrust toward Baguio over the Bauang-Naguilian Highway. The only means of meeting this potential threat was to change the planned em ployment of the 19th Division. The division was still in the San Fernando-Naguilian area due to postponement of its scheduled movement inland, and intense enemy air activity over the whole Lingayen area made it improbable that it could move in any case.80 Consequently, on 7 January, the Area Army ordered the division to assume responsibility for the defense of the sector north of a line running through Santiago, Magungunay, Mt. Bilbil, and Asin. Its main strength was to be concentrated between Naguilian and Baguio.81
Retention of the 19th Division in the Naguilian-Baguio sector, however, weakened the planned dispositions for defending the vital south flank of the northern redoubt. To remedy this situation, General Yamashita decided to effect a gradual shift northward of part of the Shimbu Group forces from the area east of Manila. As the first step, the troops withdrawn from the Manila area were to move to the Cabanatuan sector, releasing the 2d Armored Division main body for operations to the west. Later, they were to transfer farther north and take up position behind the 10th Division to defend the passes leading into the northern redoubt. The loth Division was also to broaden its deployment to take in the sector previously assigned to the 19th Division. On 8 January, the Area Army implemented its decision by ordering the following dispositions:82
While the Area Army was making these last-minute changes in its dispositions, the pre-landing phase of enemy operations in Lingayen Gulf progressed swiftly. On 7 January the heavy naval bombardment units moved deeper into the gulf and began an intensive shelling of both coastal and inland targets in the Damortis and San Fabian sectors. Enemy carrier aircraft directly supporting the invasion force supplemented the naval gunfire by bombing attacks on 23d Division defense positions and ammunition dumps, while other air attack groups bombed and destroyed vital bridges in the Calumpit, Plaridel, and Manaoag areas. On 8 January the preparatory shelling continued, taking in both the San Fabian and Lingayen sectors.85
Despite renewed neutralization strikes by enemy task force aircraft, Fourth Air Army and First Combined Base Air Force planes continued their attacks on invasion shipping in Lingayen Gulf and off the west coast of Luzon on 7-8 January. Suicide planes inflicted additional damage,86 but heavy losses sharply reduced the scale of these attacks. On 8 January the Second Air Fleet and First Combined Base Air Force headquarters were deactivated, and the First Air Fleet received orders the following day to retire to Formosa for reorganization. Fourth Air Army's decimated forces continued small-scale attack operations for a brief period, but rapidly mounting operational losses soon obliged them to retire to northern Luzon bases. Subsequent activity, for the most part, was limited to liaison and reconnaissance flights.87
The last valiant effort of the Japanese air forces in the Philippines had failed to repel General MacArthur's invasion of Luzon.