According to the Army-Navy Central Agreement of 24 July 1944, units of the Fourth Air Army assigned to attack enemy ships at sea would be under the tactical command of the Fifth Base Air Force. When the primary focus was on land operations, those units of the Fifth Base Air Force assigned to provide support to the army would be under tactical command of the Fourth Air Army. The agreement also stipulated that the Fifth Base Air Force and Fourth Air Army would destroy enemy forces in a concerted effort. An implementation agreement specifically provided for joint action before activation of the Sho-1 plan. In that case, the Navy would concentrate the Sixth and the Fifth Base Air Forces in the Philippines, hold the Third Air Fleet in reserve, and redeploy the Twelfth Air Fleet to the Home Islands. The Army would deploy to the Philippines additional fighter regiments and one heavy bomber regiment from the Training Air Army; one fighter regiment, one light bomber regiment, and one heavy bomber regiment from the 8th Air Division; and two fighter regiments from the Fifth Air Army in China. The 1st Air Division would serve as a “strategic” (actually operational) reserve.
In addition, Fifth Base Force HQ and Fourth Air Army HQ signed an agreement saying that, prior to the Sho operations, their respective forces would cooperate in attacking enemy carrier forces. A supplementary plan would be prepared to cover the Sho operations. For long-range searches, land-based naval bombers would be used, while the Army Air Forces were responsible for conducting short-range searches.
The IGHQ had pretty accurate assumptions about the future objectives of the Allied forces in the Pacific. IGHQ prepared a series of plans to cover all the contingencies. Both the Army and the Navy prepared detailed plans in case of the enemy invasion of the Philippines. However, each service drafted their plans independently. Hence, despite the critical situation in the summer and the fall of 1944, no overall and joint plan for the defense of any strategic area in the inner defense zone was ever prepared.
Sho-1 Plan and Preparations
The Army-Navy Central Agreement signed on 24 July 1944 envisaged that preparations for the “decisive battle” should be completed by the end of August 1944. The IGHQ directed that separate agreements should be reached quickly between Commander, General Defense Command, and Commander, Air Training Army; CINC Combined Fleet and the Commanders of the First, Second, and Third Air Fleet, respectively; and CINC Southern Army and Commander, Fourth Air Army.
Because of the enemy air strikes in September 1944, the IGHQ believed that the time was fast approaching when it would be necessary to activate the Sho-Go operation plan. On 22 September, the IGHQ issued an order directing that the Philippines should have priority in all defense preparations. The same directive also stated that the decisive battle would be fought some time after late October. Hence, the IGHQ directed the CINC of the Southern Army, the CINC of the China Expeditionary Force, and the Commander, Formosa Army, to complete operational preparations with the target date of late October 1944.
The Army General Staff directed the CINCs of the Southern Army, China Expeditionary Army, and General Defense Command to prepare for a decisive battle in the latter part of 1944. The Army preparations for the Sho-1/-2 had to be completed by the end of August, and for the Sho-3/-4, by the end of October.
In preparing for the Sho-1 operations, the IGHQ formally directed redeployment of several additional divisions from China and Manchuria to the Philippines. The 26th Division in Mongolia was initially assembled to move to Shanghai, while the 8th Division and 2nd Tank Division in Manchuria were moved to Pusan, Korea. By early August, these two divisions had become formally subordinate to the Fourteenth Area Army. Despite the opposition of the Fourteenth Area Army, the Southern Army decided to redeploy one division to the Davao area and one and a half divisions to the Sarangani Bay area.
On 5 August, the Southern Army HQ held map maneuvers for all subordinate high-ranking ground and air commanders on the problems involving the preparation and execution of the Sho-1 plan. Following that exercise, Terauchi issued an order directing the Fourteenth Area Army to speed up airfield construction and other defense preparations in accordance with the Battle Preparations No. 11. The most important decision was designating Luzon as the area of the “decisive battle.” The principal objective of the ground forces deployed in the central and southern Philippines in the case of the enemy invasion was to hold “strategic areas” and thereby facilitate the decisive operations by the Navy and Air Forces.
By late September, Terauchi became convinced that the enemy would land in the Philippines shortly. He urged his superiors in Tokyo that the Japanese ground, sea, and air forces, as envisaged for the Sho-1 plan, should be timely deployed for the defense of the Philippines instead of waiting for the enemy to move first. However, the Army General Staff considered it was too early to approve execution of the Sho-1 plan.
Changes in the Fourteenth Area Army. General Kuroda was abruptly relieved from his duties in late September, for devoting more time to golfing, reading, and personal matters than to his official duties. He had reportedly behaved more like an imperial governor than a combat commander. Kuroda enjoyed Manila’s sweet life. His huge mansion was well stocked with Japanese girls from the headquarters secretary’s pool.
Kuroda’s successor was General Tomoyuki Yamashita, one of the best Japanese field commanders. He commanded the 25th Army that conquered Malaya and Singapore in an only 70-day-long campaign. Some 80,000 Allied soldiers were captured. That success was achieved with only three infantry divisions totaling 30,000 men, one air division and support of naval forces. Despite this victory, Yamashita’s old nemesis General Tojo sent him to a relatively unimportant post as commander of the First Area Army in Manchuria. Yamashita returned to the favor of the Army High Command only after the fall of Tojo in July 1944. He was known as the leading Japanese expert in jungle warfare. Yamashita inspired strong loyalty and affection in his subordinates because of his willingness to share all the burdens and dangers of the soldier in the field.
Yamashita was notified of his new appointment on 25 September and arrived in Manila on 6 October. Shortly afterward, he found conditions in the Philippines unsatisfactory. Initial plans called for the establishment of two armies on Luzon. Yamashita also took direct command over all ground forces on Luzon.
The 35th Army HQ was well aware of the need to strengthen beach defenses in the Visayas and Mindanao. However, the number of troops and supplies was insufficient for the task. Adequate transportation was difficult to obtain because of the enemy carrier strikes on Cebu in mid-September 1944. Suzuki issued orders for the defense of the Visayas and Mindanao to the 16th and 100th Division, respectively. Most of the 30th Division and two infantry battalions had sufficient mobility to be quickly deployed to engage U.S. forces after they landed. The Japanese also started sending additional reinforcements to the Philippines in late September, when the 1st Division, plus a number of “sea raiding (Army high-speed suicide boats)” units, was transferred to the Fourteenth Area Army.
Leyte-Surigao Defenses. The Japanese believed that Leyte or Mindanao would be the enemy’s main objective because these areas occupied favorable locations for airfields. They did not plan to build airfields along the eastern shore of the island of Leyte. The 16th Division built defensive positions and stored ammunition as part of its defense preparations. Also, by August 1944, the Navy had mined the eastern approaches to Leyte. The primary mission of the 16th Division was to defend Leyte and Samar with the main force, maintain control of the eastern coast of Leyte, and secure positions for the employment of Japanese air and naval forces. This mission was in effect in July and remained essentially unchanged until the Allied landing at Leyte. An additional task of the 16th Division was to complete the construction of airfields on the eastern coast of Leyte island by the end of August 1944.
The 16th Division focused on building defensive positions from April 1944 on. By mid-October, the first line of defense, around the Dulag area, was practically complete. The third defense positions were established in the central part of Leyte Valley near Dagami, while the second defensive line was set up between the two others. The bulk of supplies were assembled in the central mountain range at Jaro. The 30th Division constructed some field fortifications along the southeastern coast of Surigao by early August. However, these fortifications were left unoccupied, because the division was moved to a different area prior to the Allied landing at Leyte. The 102nd Division was involved in constructing AA defenses.
In the fall of 1944, the members of the staff of the Southern Army and the Fourteenth Area Army inspected the defense positions of the 16th Division. They found that a better solution was to deploy the main force at Dagami and Burauen, instead of Tacloban. However, these orders to improve defense positions were not carried out, because the 16th Division battled Filipino guerrillas in the mountainous area west of Burauen. The 16th Division was directed to concentrate a larger part of its forces on Leyte’s east coast. However, assembling troops to provide realistic beach-defense training was difficult, because troops were scattered all over the island. They were also heavily engaged in constructing defensive positions. Thus, training for beach defense was not completed even by late September 1944.
Logistics. Until May 1944, the Japanese planned to use the Philippines as the principal base for supplying their troops deployed on Halmahera and in New Guinea. However, because of the increased effectiveness of the enemy air and submarine attacks, these plans were abandoned. In June 1944, the Japanese started to build up stock levels in the Philippines. The main depot for logistical supplies was located in the larger Manila area. On Luzon, supplies were trucked from the main depot directly to the troops in the field. Supply of army troops on Mindanao, Leyte, and Cebu was carried out by using luggers.
Reportedly, the buildup of logistical supplies in the Philippines was pretty much completed according to plan until September 1944. In the period from July to September 1944, the Army assigned about 410,000 tons of shipping to the supply of its troops in the Philippines. However, heavy Allied air strikes in September and in the following month considerably disrupted the Japanese logistical preparations. On 20 October, the Japanese had on hand in Manila only 60 percent of the stocks planned. Most of the shortages pertained to AA, antitank, and field guns and ammunition of all types. Trucks were available only in limited quantities. Yet despite all these shortages, the supply dumps in the Manila area had enough food and clothing to last from one to two months. The Japanese always tried to keep at least a two-month supply of rice on hand. The 16th division was well equipped and supplied. It had enough ammunition for one week of intensive fighting and food for one month. The only shortage was in rice.
On 24 July, the IGHQ directed the Combined Fleet HQ to intensify its defense preparations on the Home Islands, Formosa, and the Philippines. The focus was on the strengthening of the defenses of fleet anchorages. The major part of the carrier forces and other surface forces would be deployed in the Southwest Area and, depending on the enemy situation, moved to the Philippines or temporarily to Nansei Shoto. At the appropriate time, these forces would conduct “mobile operations” and, in coordination with the Base Air Force, destroy the enemy fleet. The Combined Fleet HQ was also tasked to secure, in close cooperation with other forces, the shipping routes between the Home Islands and the principal southern sources of raw materials.
Navy’s Strength. In the summer of 1944, the Japanese Navy was still a powerful force, at least on paper. Its carrier forces consisted of 11 carriers with about 500 aircraft. Despite relatively large number of carriers in service, only four eventually took part in the executing of the Sho-1 plan. The losses of naval pilots suffered in the Battle of the Philippine Sea were heavy and difficult to replace. Temporarily the carrier air groups ceased to be a fighting force. Training of the new pilots was much less thorough than it was prior to, and early in the war. The quality of training also suffered greatly because of the perennial shortage of fuel. The number of practice attacks by the new pilots had to be cut drastically because of the fuel shortages. In addition, the new aircraft suffered from poor workmanship and that in turn resulted in much damage to the aircraft during training. The Japanese problem was also compounded because of their practice of keeping frontline squadrons for too long in combat until most of the pilots were killed. The reconstitution of these squadrons was difficult because of the lack of the nucleus of skilled pilots.
The heavy surface forces consisted of nine battleships, 14 heavy and ten light cruisers. However, two of the battleships (Fuso, Yamashiro) were old and slower than other battleships. Two other battleships (Ise, Hyuga) had their 14-inch after turrets removed to make a way for a flight deck. They were too slow to serve as fleet carriers and too weak to serve as battleships. In contrast to the U.S. Navy, the Japanese Navy did not use its heavy surface ships to protect the carrier group from the enemy air attack. Another weakness was that the Japanese carriers in contrast to their U.S. counterparts lacked organic reconnaissance capability. Because of the overemphasis on the offensive aspects of warfare, the Japanese tried to maximize the number of attack aircraft on board the carriers. Hence, no specialized carrier-based reconnaissance aircraft was ever developed. The Japanese Navy preferred the use of floatplanes and seaplanes carried by cruisers for reconnaissance tasks. All this in turn resulted in a rather perfunctory training of the Japanese naval aircrews for air reconnaissance tasks. The fleet commanders also preferred heavy cruisers as flagships. This, in turn, considerably limited their ability to command their forces. Toyoda’s flagship was initially a light cruiser (Oyodo), but he shifted his command post ashore at Hiyoshi, near Tokyo. There was a great lack of destroyers and escorts. Only 30 destroyers were available for the striking forces of the fleet out of a total of 63 destroyers on the list. This number also included nine destroyers under repairs, eight 2nd class destroyers and several others were suitable only for escort duties. By early August 1944, some 70 submarines were on the list, but only about 50 were operational.
First Mobile Fleet (later Mobile Force, Main Body) Preparations. The First Mobile Fleet underwent intensive training near Bungo Channel in the late summer and early fall of 1944. Ozawa believed that most likely the Sho operations would be carried out before the end of 1944. This would require revising the training schedule. Therefore, all CarDiv 3 units had to be capable of daytime carrier operations by the first week of October, and CarDiv 4 by about 10 November. By the end of December, CarDiv 1 would have aircraft capable of daytime operations in sufficient numbers for two air groups. Because of the inadequate training level of carrier aircrews, the carrier force could not be used jointly with the First Diversionary Attack Force until 10 November. As it turned out the enemy invasion came about one month too early for the Japanese.
The map exercise of the First Mobile Fleet was held at Kure on 1–3 September. One conclusion drawn from that exercise was the practical impossibility, because of the widely dispersed basing areas for Ozawa’s force, of exercising effective control of the First Diversionary Attack Force in the Sho-1 or Sho-2 Operation.
On 6 October, after the Japanese received intelligence about pending strikes by U.S. bombers based in China against targets in the Home Islands, Ozawa’s force stopped all training and returned to the Kure-Iwakuni area. Ozawa ordered final preparations to be made in case of enemy attack in the inner defense zone, especially against the Philippines.
First Diversionary Attack Force. In the aftermath of the battle of the Philippine Sea, Kurita’s Second Fleet after two weeks at the Kure naval base in the Inland Sea sailed out for Lingga archipelago, where it arrived in mid-July. During a three months’ stay at Lingga, radar was installed for the first time in all battleships and cruisers. Based on lessons learned in the Battle of the Philippine Sea, the AA guns were fitted on all available deck space. Among other things, the number of 25-mm machine guns was increased to 120 for battleships, 80 for cruisers, and 40 for destroyers. Training of Kurita’s force for the forthcoming operation was made easier because of ample fuel supplies available from Palembang, Sumatra. However, the Lingga anchorage did not have any AA defenses. This was one of the serious omissions on the part of the Japanese commanders responsible for the ground defenses of the area.
The First Diversionary Attack Force conducted extensive training in accordance with the outline of the Sho operation. Training included the use of organic AA defenses and evasive maneuvering in repulsing enemy attacks from the air. Reportedly, the training at Lingga gave enough confidence to ships’ crews that the fleet could withstand enemy air attacks even without friendly combat air patrols. Special emphasis was given to the use of heavy guns at night and conducting night torpedo attacks. Methods of penetrating an enemy’s anchorage and of destroying enemy screening forces followed by the attack on the enemy transports were also practiced. Kurita’s forces studied the three most likely areas of a penetration maneuver: Lamon Bay, Leyte Gulf, and Davao Gulf. The Japanese Navy never practiced such large-scale penetration tactics in peacetime.
Kurita’s staff felt that the primary objective should be the annihilation of the enemy carrier forces, while the destruction of convoys should be the secondary objective. However, that view was contrary to the then-declared Combined Fleet HQ’s “policy.” The greatest concern of Kurita’s staff was that friendly aircraft might be unable to locate the enemy force at their maximum effective search radius. In such a case, it would be impossible for surface forces to attack the transports before they began unloading. Kurita and his staff correctly concluded that if the attack by the Japanese surface forces were delayed until several days after the enemy invasion, then, judging by past experiences, the enemy transports would be emptied by the time the Japanese surface forces arrived. It was considered foolish to sink empty transports at the risk of losing an elite surface force.
Many officers openly complained that the Combined Fleet HQ’s view was unsound. They argued that, although all efforts should be made to penetrate into the enemy anchorage, if the enemy carrier forces were within striking distance, then the objective should shift to fighting a fleet engagement. Reportedly, this proposal was fully explained to the Combined Fleet’s representatives at the Manila conference, and later submitted in writing.
The original plan of the First Diversionary Attack Force, formulated on 18 September, envisaged penetration of the enemy-landing objective as a single force. In preparing for the Sho-1 Operation, Kurita’s force held three war games (4–6 September, 9 September, and 14–16 September). In each of them, the First Diversionary Attack Force carried out a penetration maneuver at Davao Gulf. By mid-October, Kurita concluded that the invasion of the Philippines was inevitable. On 15 October, he stopped all training, put his forces on alert, completed all the replenishments, and issued an order to all units to prepare for sortie out from Lingga archipelago.
Southwest Area Force. After July 1944, the Navy’s strength in the Philippines area was gradually increased. There were 17 SCs, one patrol boat, three minesweepers, three torpedo boat units, and one suicide boat unit with about 400 boats. The newly formed 31st and 33rd Special Base Units based at Manila and Cebu respectively would operate in the waters of the northern and central Philippines. The 955th Air Unit was assigned to provide air protection of surface ships. After August, nine reinforced construction battalions were sent to various parts of the Philippines to strengthen land defenses and construct air bases. In addition, they were tasked to build bases for special attack units.
By mid-August, the Southwest Area Force consisted of six major force elements: the East Indies Force (2nd Southern Expeditionary Fleet); the Philippine Force (3rd Southern Expeditionary Fleet); North of Australia Fleet (4th Southern Expeditionary Fleet), the Western Force (1st Southern Expeditionary Fleet); the Third Base Air Force (Thirteenth Air Fleet); and the Fifth Base Air Force (First Air Fleet). The First Air Fleet had been completely reorganized in Japan after suffering very high losses in the Marianas. It was transferred from the Combined Fleet to the Southwest Area Force and its headquarters was moved to Davao, Mindanao. The main tasks of the Southwest Area Force were to secure the Southwest Area in cooperation with the Army, protect sea transportation, destroy enemy shipping, and provide transport for the Army.
Special Sea Attack Units. During July and August 1944, the Japanese formulated plans to build bases for Special Sea Attack units, composed of suicide boats, Type A midget submarines, and one-man suicide torpedoes (Kaitens).89 The plans called for the construction of bases for special attack units at Davao, Tacloban, Sarangani, Zamboanga, Lamon Bay (Pollilo islands), Ramon Bay, Taya (Tayabas) Bay, and Batangas (southwestern Luzon). However, work on the Davao and Zamboanga bases ceased in October 1944.
Prior to the Allied landing at Leyte, the Japanese completed construction of a base for Type A midget submarines at Cebu and a suicide boat base at Corregidor. A suicide boat unit at Davao was unable to relocate to Gasandakan. More than 100 suicide boats were sent from Regasupi to Davao, but only five boats arrived. About 150 suicide boats, organized in seven units, were based at Corregidor (the base there was completed by the end of 1944). The Japanese also completed the construction of bases at Davao and Zamboanga. However, after the enemy landing at Leyte, the supply route was cut off, and the Japanese were forced to discontinue construction of the bases in the southern part of the Philippines. Initially, the Japanese also planned to build bases for PT boats at Manila, Cebu, and Davao. A few of these boats were deployed to Davao. Afterward, their movements were difficult, and about twelve or thirteen of the remaining boats were stationed in southern Luzon.