Enemy Airfields Reported in Use, September 1944
Enemy Ground Dispositions, 30 September 1944
On 24 July, the IGHQ’s Army section issued the basic order governing Army operations defending the inner zone of defense. The order repeated almost verbatim the IGHQ’s directive about the decisive battle and the anticipated time of the main enemy attack on the Japanese defense zone.
The Army directive also included the deployment plan for the movement of specific ground forces from various areas along the inner defense line to the enemy’s possible landing (objective) points. CINC, Southern Army, was directed to prepare a force with one brigade as a nucleus in the northern Philippines, to be ready for redeployment to Taiwan or Nansei Shoto. The Formosa Army commander would have a similar force in readiness for deployment to the northern Philippines or Nansei Shoto. If Sho-1 and Sho-2 were activated, the IGHQ would prepare one division near Shanghai for redeployment to the Philippines, Nansei Shoto, or the Taiwan area. In case of enemy invasion, the Southern Army would concentrate all its available ground and air strength for the decisive battle on Luzon. The Fourth Air Army had the responsibility for operations in the Philippines and eastern NEI, including western New Guinea, while the Third Air Army’s responsibility encompassed the area west of and including Borneo.
On 24 July, Terauchi convened a conference of subordinate commanders in Manila to discuss the IGHQ’s directive for the defense of the Philippines. He explained that the Fourteenth Army was directed to prepare for a decisive ground battle on Luzon. If the enemy landed in the central or southern Philippines, the Fourteenth Army’s responsibility would be limited to delaying defense and defending local air and naval bases. On 4 August, as efforts to prepare the defense of the Philippines intensified, the IGHQ elevated the Fourteenth Army as the Fourteenth Area Army. The newly organized 35th Army became subordinate to the Fourteenth Area Army and was assigned the tasks of defending the Visayas and Mindanao.
In late September, the IGHQ’s Army section estimated that the enemy would mount a two-pronged attack on Luzon, with MacArthur’s forces coming from the south and Nimitz’s from the central Pacific. MacArthur was expected to seize lodgments in the Davao and Sarangani areas and then move to Zamboanga or the Leyte–Samar area prior to the attack on Luzon. For the Japanese, the only uncertainty was where the enemy’s next blow would fall. In their view, an enemy invasion of Morotai would indicate that the next target would be southern Mindanao, while seizure of the Palaus could lead to the invasion of Leyte.
The 35th Army Plans. Lieutenant General Sosaku Suzuki led the 35th Army. He came to that post from the position of the chief of the Central Shipping Transportation HQ. Suzuki also enjoyed a well-earned reputation as a first-rate organizer and an effective combat commander. On 17 August, Suzuki presented an outline of the operational plan to his subordinate tactical commanders at the 35th Army’s HQ on Cebu. The plan, later known as “the Suzi Orders,” envisaged the 100th Division to defend the Davao Area, while the Leyte area would be defended by the 16th Division. The 30th Division and two infantry battalions of the 102nd Division plus reinforcements from the Fourteenth Area Army would serve as mobile reserve, capable of quick deployment to either of these two areas. In case the enemy landed with its main forces at Davao, the main force of the 30th Division, part of the 102nd Division, plus some other smaller units would be committed to that area. In the event of an enemy landing on Leyte, the mobile reserves would land at Ormoc and destroy enemy forces on the island. If the enemy landed simultaneously at Leyte and Davao, the 35th Army’s plan was to quickly deploy the 30th Division to Leyte to destroy enemy landing forces there.
In late August, Suzuki received orders to deploy a reinforced infantry division to the Davao area and the 16th Division to Leyte. In addition, he was directed to deploy three battalions to Sarangani Bay and three other battalions to the vicinity of Zamboanga; two battalions to Jolo archipelago and one “strong” unit in the vicinity of Surigao. The 55th independent mixed brigade would be also assigned to the 35th Army.
The plans for the defense of the Leyte-Surigao area directed the 16th Division to offer strong resistance to the enemy landing. The 16th Division would assume command of all the air and naval units within its zone of responsibility. Additional reinforcements from the Visayas district would be sent as well. However, no plans were made at that time to redeploy Japanese troops from Luzon to Leyte. In case the basic defense plan failed, the 16th Division would withdraw to the mountains west of the Tacloban airfield and block the enemy advance into the island’s interior. The Japanese planned to have sufficient ammunition for half of the division and food for 20,000 men for six months.
The 35th Army plans were based on the assumption that the most likely area of the enemy’s invasion was Mindanao because of the many Japanese airfields and naval bases there. The 35th Army HQ believed that the enemy might plan to capture Sarangani Bay because of the airfields nearby. The enemy might also try to capture some lodgments in the Zamboanga Peninsula and Jolo Island. The enemy also could seize the southeastern area of Surigao, which held a key position but was weakly defended. The 35th Army HQ considered the enemy landing at Leyte secondary in importance to Davao. The enemy might also carry out airborne landings at Misamis Oriental (northern Mindanao) and the airfields on Cebu, Negros, and Panay. The likelihood that the enemy might attempt to seize Samar was considered remote because of the difficult terrain there. As it happened, the Allied planners held the same view.
Army Air Plans. Two Air Armies were subordinate to the Southern Army; the Third Air Army in Singapore was responsible for the defense of Sumatra and Burma, while the Fourth Air Army in Manila had responsibility for the defense of the Philippines. The Fourth Air Army’s primary mission was to interdict enemy shipping and, if given the opportunity, to attack enemy warships. If it had to operate alone, the Fourth Air Army would carry out raids against enemy carrier forces and air bases and interdict enemy aircraft. After an enemy landing, the Fourth Air Army’s task would shift its attacks against enemy invasion forces, particularly troop transports. These actions would start a day before the planned penetration of the landing area by the Japanese heavy surface forces. The Southern Army recommended that enemy aircraft carriers should be the targets of priority. However, that suggestion was rejected by the IGHQ. The Army section insisted that not only enemy carriers but also convoys should be attacked as well.
In October 1944, the Fourth Air Army issued a plan envisioning the destruction of enemy forces in cooperation with Army troops, and of enemy carrier–based aircraft and airfields in cooperation with the Navy’s land-based aircraft. If the enemy carriers were operating alone, Army aircraft would conduct small-scale surprise attacks at hours of darkness. The objective would be to prevent the enemy from obtaining new air bases in the Philippines. The bulk of fighter aircraft would be deployed to the central and southern Philippines to destroy enemy amphibious forces if they landed there. The Army aircraft deployed in Mindanao, Celebes, and northern Borneo would prevent enemy forces from establishing bases on Halmahera and in western New Guinea. They would destroy enemy aircraft by staging attacks from the bases in the southern Philippines. The Japanese heavy bombers would be deployed in the central and southern part of the archipelago to attack the enemy convoys approaching the Philippines.
All the naval planning for the Sho operations was conducted by the Combined Fleet HQ. Naval components of the Sho-1 plans were made independently of the Army. Admiral Toyoda believed that if the enemy ever obtained a foothold in the Philippines, he would try to capture other positions in the archipelago as well. If the enemy seized the Philippines, shipping routes between the homeland and the Southern Resources Area would be cut off, derailing the plan to wage a protracted war. The Japanese would be cut off from liquid fuel sources in that area. Even if the Combined Fleet remained intact, it would have been, in his words, “a white elephant.” A continued enemy advance would put the fleet in danger of annihilation. Hence, in Toyoda’s view, there was no other option but to commit the entire fleet to defense of the Philippines. Toyoda explained in 1950 that the Navy’s plan for the defense of the Philippines was contrary to all the principles of tactics. It also represented a flagrant departure from common sense to employ surface forces without obtaining control of the air. Yet he also believed that under the circumstances there was really no other alternative. The Japanese Navy could not just stand idly by when the enemy invaded the Philippines.
The major challenge facing Toyoda and his staff was the optimal employment of surface forces in defense of selected “strategic” positions within the inner defense zone. This problem was compounded by the battering the Combined Fleet had taken during the Battle of the Philippine Sea in mid-June 1944. The Combined Fleet lacked both the carriers and the well-trained pilots to fight a major battle with the U.S. Navy. Another problem was that Japanese surface forces were widely dispersed, from the Fifth Fleet in the north to the Second Fleet in the south. Before these forces could be concentrated at the enemy’s landing objective, they first had to evade or repulse attacks by enemy aircraft and submarines. Because oil supplies were low, the Japanese had to base heavy surface forces at the Lingga archipelago, where there was an abundance of oil, but keep carrier forces in the Inland Sea to train pilots for carrier air groups. The Japanese had little hope of completing their training and reuniting carriers with the surface forces at Lingga before the enemy’s next blow.
Organizational Changes. Between late July and mid-October, the Combined Fleet’s task organization underwent numerous changes, many arising from uncertainty about the time and place of the expected decisive battle. Other organizational changes seem to reflect fuzzy planning on the part of Toyoda and his chief of staff, Vice Admiral Ryunosuke Kusaka. On 1 August, Toyoda changed the tactical designation of the numbered fleets. Second Fleet became the First Diversionary Attack Force (1YB), the First Air Fleet became the Fifth Base Air Force (5 FGB), Second Air Fleet was designated Sixth Base Air Force (6 FGB), Third Air Fleet was redesignated Seventh Base Air Force, and the Eighth Fleet became the Outer South Seas Force. In early August, the Fifth Fleet was redeployed to the western part of the Inland Sea and put under the command of the First Mobile Fleet (First Striking Fleet in the Magic dispatches) for the Sho operations. Its tactical designation was changed to the Second Diversionary Attack Forces (2YB).
On 9 August, the Combined Fleet HQ took over full operational control over the General Escort Forces and Naval District and Guard Forces. Directly subordinate to the Combined Fleet were the Mobile Forces (the First Mobile Fleet, the First and Second Diversionary Attack Force); the Sixth and Seventh Base Air Forces, the Inner South Seas Forces (remnants of the Fourth Fleet plus the attached Base Air Forces); the Advance Expeditionary Force (Submarines); and the 31st Army (the Army forces deployed in the western Carolines, the Marianas, and the Bonins). On 21 August, the China Area Fleet also became subordinate to the Combined Fleet, but only during the pending Sho operations.
Another major organizational change came in mid-September when the First Mobile Fleet became the Mobile Force, Main Body (KdMB). Vice Admiral Jisaburo Ozawa remained the commander of the newly designated force. Ozawa was one of the most able and experienced Japanese naval officers. He was intelligent and thoughtful and had a dignified presence. Directly subordinate to Ozawa were Vice Admiral Takeo Kurita, commander of the First Diversionary Attack Force, and Vice Admiral Kiyohide Shima, who commanded the Second Diversionary Attack Force.
In the aftermath of the Allied invasion of the Marianas, the Japanese withdrew almost all their submarines to the Inland Sea, except for a few boats used for transporting materiel to bypassed garrisons and carrying out attacks against enemy shipping. All operational submarines in the Inland Sea were organized in three groups. The 1st Submarine Group (13 boats) was undergoing either repairs or post-repair trials. The 7th Submarine Group (two boats) was directed to conduct ambushes and transport materiel to the bypassed Japanese garrisons in the enemy rear area. The 11th Submarine Group (12 boats) was conducting shakedown cruises in the Inland Sea.
First Tentative Plans. In the first week of August, Combined Fleet HQ prepared its initial plan for defense of the Philippines. Although there were numerous changes to the plan after 17 October, the basic operational idea remained essentially unchanged. The plan was formally presented to the subordinate tactical commanders for discussion at the conference organized by the Combined Fleet HQ and held at Manila on 10 August. The principal objective would be to destroy enemy transports before they disembarked troops and materiel. The plan envisaged the timely deployment of the First Diversionary Attack Force from the Lingga Archipelago to Brunei Bay, northern Brunei, and subsequent advance to the enemy’s landing objective (then assumed to be Davao Bay), for a penetration maneuver. Mobile Force, Main Body and Second Diversionary Attack Force would sail out of the Inland Sea to attack enemy carrier groups in the area between Mindanao and the Palaus. The operational idea also envisaged attacks by land-based aircraft against enemy carriers from their bases in the central and southern Philippines. Air reinforcements would be sent from the Home Islands and China and staged through Formosa and Luzon. In case enemy transports were already disembarking troops, the First Diversionary Attack Force would penetrate the anchorage within at least two days of the enemy’s landing.
The day of the penetration maneuver was designated as X-Day; while the day of the general air offensive was designated as Y-Day (it corresponded to X-1 Day). The success of the plan depended on the timely detection of enemy forces, and proper deduction of the enemy’s intentions. The Japanese planned to conduct air searches up to 700 miles from land bases to provide sufficient warning of the approach of the enemy invasion forces.
The plan envisioned the Japanese “Defense Forces” (those deployed ashore) to make every effort to annihilate the enemy on the beaches. Should the enemy succeed in landing, the Defense Forces would “fight to the death” and prevent the enemy from capturing and using nearby airfields. Combined Fleet HQ also contemplated bringing in troop reinforcements for a counter-landing operation aimed to crush enemy amphibious forces. This effort would be synchronized with the heavy surface forces’ penetration of Leyte Gulf.
The original plan of Combined Fleet HQ contemplated that the First Diversionary Attack Force (7 BBs, 12 CAs, 3 CLs, and 20 DDs), in cooperation with Base Air Forces, would decisively engage the enemy surface force opposing its advance, then destroy enemy transports and troops at the landing objective area. Its secondary task was to destroy damaged enemy carrier forces. Reportedly, tactical factors essential for success were intentionally ignored in planning the employment of the First Diversionary Attack Force in the Sho-1 Operation. Also, no proper evaluation had been made of potential enemy strength in the area.
In the next evolution of the Sho-1/-2 plans, completed in early September, Combined Fleet HQ envisaged that the Mobile Force, Main Body (4 CVs, 3 CVLs, 2 BBs/XCVs, 1 XCV, 2 CLs, 9 DDs), and the Second Diversionary Attack Force (2 CAs, 1 CL, 7 DDs) would support the First Diversionary Attack Force penetration of Leyte Gulf by diverting enemy carrier forces to the north. These two forces would reach a position northeast of the Philippines by X-1 or X-2 Day, then attack enemy carrier forces and try to disrupt the enemy’s “rear supply forces.” Their movements would be coordinated with those of the First Diversionary Attack Force. Ozawa was well aware that his force, with its inadequately trained carrier pilots, wasn’t strong enough to conduct mobile operations. Hence, he insisted that the strength of his force should be reduced to the minimum necessary to successfully carry out the feint in the north. The new variant of the plan envisaged strengthening of the First Diversionary Attack Force by attaching to it one CarDiv as well as BatDiv 2 and DesRon 10. After CarDiv 1 became ready for combat (end of December), it would be incorporated into the Mobile Force, Main Body (or possibly the Second Diversionary Attack Force).
Combined Fleet HQ’s planners contemplated the employment of all Japanese submarines only in case of the activation of the Sho-1/-2 plans. Their principal mission would be then to “intercept” the enemy and obtain control of the invasion area.
For logistical support, two groups of supply ships were assigned to the First Diversionary Attack Force: the First Supply Force, with eight tankers and two coastal defense ships, deployed in the Singapore-Brunei area; and the Second Supply Force, with five tankers and one coastal defense ship, deployed at Sam-Urucan and Singapore-Bako areas. However, only one tanker (then based at Sana, Hainan) was capable of refueling at sea. The supply group for Ozawa’s force was not established until 18 October.
Combined Fleet HQ contemplated that in case of the activation of the Sho-1, the Sixth Base Air Force would redeploy a major part of its forces from the bases on Kyushu to southern Formosa or the northern Philippines. Part of the 8th Air Division would be moved to the Philippines. If the Sho-2 plan were activated, a major part of the 8th Air Division (minus search aircraft) would be dispersed to Kyushu and Taiwan to avoid initial enemy attacks. For the Sho-2 operation, the Sixth Base Air Force would control the Fifth Base Air Force in the Philippines, a major part of the Seventh Base Air Force in Kyushu, and the T-Attack Force initially deployed on Kyushu.
According to the original plans for Sho-1/-2, if the enemy attacked objectives in the decisive battle area, the Fifth and Sixth Base Air Forces would wait on the approach of the invasion forces, drawing the major part of the enemy’s strength as near as possible, and on X-1 Day decisively engage enemy forces in cooperation with other naval forces and the Army Air Forces. The priority targets for the Base Air Forces were enemy carriers followed by amphibious forces. In case Sho-1 and Sho-2 were simultaneously activated, the Sixth Base Force would engage and destroy enemy carrier forces in the Nansei Shoto, followed by those operating off Formosa. Afterward, the decisive battle would be fought in the Philippines.