- 192 - Pacific War Podcast - Operation Downfall - July 22 - 29, 1945

Last time we spoke about the fall of Wewak. In June 1945, Allied forces, led by General George Stevens, intensified their campaign to capture the strategic town of Wewak in New Guinea. After years of grueling combat, they relentlessly pressed against entrenched Japanese defenses, including the remnants of General Mano's 41st Division. The Australians achieved critical victories by securing vital supply routes and establishing new airfields, facilitating their advance. By May 8, after intense fighting, Australian troops effectively seized Wewak Point, eliminating entrenched Japanese soldiers in bunkers and caves. Despite suffering casualties, the Australians distinguished themselves through bravery and tactical ingenuity. Ultimately, the successful capture of Wewak marked a pivotal moment in the Pacific campaign, showcasing the determination and spirit of the Allies as they pushed towards victory in the Pacific Theater, bringing an end to a crucial chapter of the war.

This episode is Operation Downfall

Welcome to the Pacific War Podcast Week by Week, I am your dutiful host Craig Watson. But, before we start I want to also remind you this podcast is only made possible through the efforts of Kings and Generals over at Youtube. Perhaps you want to learn more about world war two? Kings and Generals have an assortment of episodes on world war two and much more  so go give them a look over on Youtube. So please subscribe to Kings and Generals over at Youtube and to continue helping us produce this content please check out www.patreon.com/kingsandgenerals. If you are still hungry for some more history related content, over on my channel, the Pacific War Channel you can find a few videos all the way from the Opium Wars of the 1800’s until the end of the Pacific War in 1945. 

After the fall of Okinawa, the Allies were mopping up campaigns across the Asia-Pacific and planning for what was assumed to be the most cataclysmic battle yet, the invasion of the Japanese home islands. First we are going to travel back to Luzon. By mid-June, General Krueger’s 6th Army had successfully captured all key objectives in northern Luzon, southern Luzon, and the area east of Manila, which serves as the capital of the Philippines. Although General Yokoyama’s poorly equipped 41st Army had been rapidly scattered and forced into hiding, General Yamashita’s Shobu Group still retained enough strength to continue its resistance in northern Luzon. The Shobu Group was primarily gathering its units in a desperate last-stand position along the rugged valley of the Asin River, an area known for its difficult terrain. Interestingly, General Krueger underestimated Yamashita's strategic intentions, still expecting him to make his final stand in the Cagayan Valley, located in the northern part of Luzon. With this assumption, Krueger believed that if General Beigthler’s 37th Division could maintain its rapid advance towards Aparri, situated at the northern tip of Luzon, they might be able to conclude the Luzon Campaign in a pivotal stroke.

However, intelligence indicated that units of the Shobu Group were retreating into the Cordillera Central mountain range, a formidable natural barrier, located between Routes 4 and 11. In response, Krueger ordered the 1st Corps to exert strong pressure on this mountainous region from the north, south, and west. To implement this strategy, General Swift directed the 6th, 25th, and 33rd Divisions to clear the supply route between Baguio and Aritao, ultimately sealing off Yamashita's last-stand position from the south. Meanwhile, Colonel Volckmann's guerrilla forces were instructed to advance east from Cervantes to capture the crucial junction of Routes 4 and 11 at Sabangan. Recognizing the importance of controlling key roadways, the 63rd Regiment was tasked with pushing up Route 4 to seize the strategic location of Kiangan. In the south, the 130th Regiment began probing southeast towards Pigkian, while the 20th Regiment continued to apply pressure on the remnants of the now-battered 2nd Tank Division. Ultimately, General Iwanaka’s weakened forces narrowly avoided entrapment along the Bambang-Pingkian road, retreating northward via treacherous mountain trails and river valleys. They reached the Tubliao area just as early July arrived, illustrating the persistent and relentless nature of this campaign.

Looking northward from Cervantes, Volckmann’s guerrilla fighters launched attacks toward both Mankayan and Sabangan. By the end of June, their efforts had pressured the beleaguered 19th Division to hastily withdraw from Bontoc, a significant town located in central Luzon, and Sabangan. However, General Ozaki’s forces maintained a formidable defensive position at the Lepanto Mine, an area known for its mineral wealth and strategic significance. On June 16, the 63rd Regiment began its advance up Route 4, which runs north through the central highlands toward Kiangan, a town that was critical for controlling the region. By the evening of the following day, American forces had successfully breached the defensive line established by the 105th Division at the Rayambugan Farm School, a local educational institution that was repurposed for military use during the conflict. Continuing their push, the 63rd Regiment encountered the main defenses of General Tsuda on June 19 along Route 4. However, over five days of fierce fighting, utilizing only one battalion for the attack, gained little ground for the Americans. Recognizing the need for greater force, they reinforced their assault on June 24. By June 26, the 63rd began to break through towards Hucab, a small settlement, and by June 29, they had overcome the last organized resistance in the area.

Meanwhile, the 37th Division also made significant advances. Resuming its drive up Route 5 on June 17, the 148th Regiment successfully pushed forward to Naguilian, a town that marks a key waypoint on this route. Two days later, the front-line troops reached Bangag, yet here they encountered increased resistance. They were now facing elements of Major-General Yuguchi Shuntaro’s 80th Brigade, which was attempting to move south along Route 5. In a series of running engagements from June 19 to 23, the 37th Division inflicted heavy casualties, killing over 600 Japanese soldiers and capturing nearly 285 more in the challenging fifteen-mile stretch between Bangag and Balasig. The remnants of the Yuguchi Force were ultimately forced to retreat eastward into the rugged and uncharted wilderness of the Sierra Madre mountain range, illustrating the intense and chaotic nature of the conflict.

General Krueger deemed it essential to execute an airborne operation over the northern Cagayan Valley to ensure the success of the 37th Division's advance. It’s possible that Krueger’s motivation also stemmed from a desire to secure northern Luzon before the 8th Army took control of operations, which was scheduled for July 1. Despite contrary reports from various sources, including the United States Armed Forces in the Philippines Northern Luzon, 1st Corps, the 37th Division, and ALAMO scout teams, Krueger concluded that Japanese forces in the Cagayan Valley were retreating "in wild disorder on Highway 5 towards Aparri." It’s worth noting that, in actuality, the general movement of Japanese troops had been southward for weeks, and no Japanese unit intended to take refuge in Aparri, a flatland area surrounded by mountains that made it a poor defensive position. Based on his assessment of the situation, Krueger decided that in order to achieve the complete destruction of the fleeing enemy forces, he would launch a vertical envelopment of airborne troops to close any escape routes and prevent the Japanese from evading capture in Aparri. Consequently, on June 21, Krueger ordered a battalion combat team from the 511th Parachute Infantry of the 11th Airborne Division to parachute near Aparri on June 23. However, on June 21, the Connolly Task Force entered Aparri without facing any opposition. By the evening of June 22, elements of the Task Force had advanced ten miles south along Route 5, managing to secure the Camalaniugan Airstrip, a crucial airfield integral to the logistics of both sides. Despite the successes of the reinforced Connolly Task Force, Krueger did not change his mind about the desirability and necessity for the airdrop. Instead, he concluded that the "seizure of Aparri without opposition by elements of the Connolly Task Force on 21 June 1945, together with the almost unopposed advance of the 37th Division, indicated clearly that the time had come for mounting the airborne troops to block the enemy's retreat in the Cagayan Valley." It is not clear just what retreat Krueger expected to block.

On the morning of June 23, the paratroopers dropped into Camalaniugan unchallenged and immediately began their advance southward to make contact with the 37th Division. That same day, the 129th Regiment took over the offensive, heading north towards Tuguegarao, a significant town in the region. Tuguegarao fell without resistance by June 25. By nightfall, forward elements of the 129th had pushed ten miles beyond Tuguegarao, reaching the town of Iguig. The following day, June 26, the forces made contact with the paratroopers at the Paret River, further solidifying their position. By the close of June, Japanese resistance in the Cagayan Valley had subsided, and General Yamashita’s Shobu Group, still capable of fighting, found itself encircled in a last-stand area that would become known as the Kiangan Pocket, named by the Filipino-American forces engaged in its reduction. As the campaign progressed, the last elements of the 25th and 33rd Divisions were relieved. General Gill’s 32nd Division took over control of the Baguio-Ambuclao sector, while the bulk of General Hurdis’ 6th Division assembled at Hucab. This marked a significant transition as it signaled the conclusion of operations for Krueger’s 6th Army and Swift’s 1st Corps. The command would soon shift to General Eichelberger’s 8th Army and General Griswold’s 14th Corps, who would carry out further operations throughout Luzon.

General Griswold's plans called for relentless pressure to be maintained against the Shobu Group, which was concentrated in an area known as the Kiangan Pocket. In line with this strategy, Volckmann’s guerrilla fighters continued their assaults towards key locations such as Mankayan, Sabangan, and Bontoc. The 126th and 127th Regiments advanced north along Route 11 and into the Agno Valley, engaging mixed forces from the 58th Independent Mixed Brigade and the 19th Division. Simultaneously, the 20th and 63rd Regiments were preparing to renew their attack against the 105th Division located at Kiangan, as the advance led by General Hurdis had been halted by torrential rains that had severely damaged roads and bridges. Meanwhile, the 1st Regiment made its own push northward along Route 4 towards Banaue, a town famous for its rice terraces and mountainous landscape.

On July 9, Volckmann’s 15th Regiment finally secured Sabangan. The following day, the 11th Regiment captured Bontoc while the 66th Regiment began to break through the defenses set up by General Ozaki in the Lepanto Mines-Mankayan area. By July 12, Kiangan fell to the 63rd Regiment; however, they soon faced even heavier rains, which compelled General Hurdis to halt his advance once again. On July 20, the 1st Regiment reached Banaue. The next day, they made contact with elements of the guerrilla 11th Regiment at Polis Pass before turning east along Route 389. Here, they aimed to engage a concentration of around 2,500 Japanese soldiers from the 103rd Division and the 4th Air Division. Back in the west, Mankayan also fell on July 20. Five days later, elements of the 15th and 66th Regiments made contact at the junction where Routes 11 and 393 intersect. The 19th Division was withdrawing into the upper Agno Valley to establish defensive positions, blocking the northern, western, and southern approaches to Toccucan, a small but strategically important area. The 15th and 121st Regiments began their assaults toward Toccucan, but they soon encountered remnants of the 19th Division, who proved to be still capable of effective resistance. At the same time, the 66th Regiment moved south along Route 11 to establish contact with troops from the 32nd Division, pressing the offensive forward.

Looking east on July 24, the 20th Regiment took over positions at Kiangan and began an advance towards Kiangkiang and the Asin River. However, the Americans encountered greater resistance than anticipated along this route, making only a meager gain of three miles by August 15. At the same time, other units were dispatched south towards Tubliao to block the retreat of General Iwanaka’s remaining forces. On July 29, elements of the 66th and 127th Regiments finally established contact near Gambang. They then shifted east into the Agno Valley, close to Buguias, and initiated a southward drive to link up with the 126th Regiment, which they successfully met on August 8. By August 15, Volckmann’s guerrillas found themselves four miles short of Toccucan from the northwest and a mile and a half short from the west. In the eastern front, elements of the 1st and 11th Regiments advanced south from Banaue along Route 390, reaching a point about five miles south of Banaue by August 9. That same day, they also cleared Route 389 to the east, securing additional pathways for movement. Additionally, during this time, the 37th Division conducted vigorous patrols east of the Cagayan River, pushing enemy troops deeper into the Sierra Madre mountains. Unfortunately, this relentless pressure resulted in an estimated 1,000 Japanese casualties by August 15. Throughout a month and a half of grueling fighting in steep, treacherous terrain and under miserable weather conditions, the Filipino-American forces struggled to project any significant strength into the Asin Valley. They suffered approximately 1,650 casualties in total. In contrast, the 8th Army estimated that Japanese casualties during the same period reached around 13,500, with many killed or succumbing to starvation and disease.

This marked the effective conclusion of the Luzon Campaign, a campaign that would soon be overshadowed by Japan's surrender. General Yamashita estimated in June that he had sufficient supplies to sustain his forces until mid-September. Given the scale of effort the 8th Army was willing to dedicate to the campaign between July 1 and August 15, it seems likely that Yamashita would have met this deadline. When food supplies were depleted, Yamashita planned for his most effective remaining troops to attempt a breakout from the Asin Valley into the mountains of far northwestern Luzon, where he hoped to find more provisions. Those not involved in the breakout were to conduct banzai attacks along all fronts to cover the retreat of the main forces. Yamashita anticipated that whether or not the breakout succeeded, it would signal the complete disintegration of his forces. He even planned to commit hara-kiri amidst the chaos of battle. As a result, the end of the war arrived about a month before Yamashita was prepared to officially acknowledge his defeat. By any measure, the Shobu Group accomplished the delaying mission that Yamashita had envisioned. Throughout the 6th Army's control of operations on Luzon, the maximum commitment of major ground forces against the Shobu Group included four reinforced U.S. Army infantry divisions, one separate regiment combat team, an armored group, Volckmann’s , and the Buena Vista Regiment. When hostilities ceased on August 15, the Shobu Group was still "entertaining" three reinforced divisions: the 6th, 32nd, and 37th. Additionally, it had a significantly strengthened, the Buena Vista Regiment, and various other guerrilla units. After the war concluded, approximately 50,500 Japanese troops emerged from the mountains of northern Luzon, with nearly 40,000 of these coming from the Asin Valley's last-stand area. Ultimately, the war ended with about a third of the Shobu Group's peak strength still alive and capable of conducting organized and determined delaying operations. It is clear that, over the seven and a half months since January 9, the Shobu Group executed a remarkably effective delaying action. Despite the circumstances, the 14th Area Army had achieved its objective of tying down as many Allied forces as possible in Luzon. This diversion was critical, as it allowed the Japanese Empire valuable time to fortify its defenses in the Home Islands. 

Reflecting back to January, General Prince Higashikuni Naruhiko’s General Defense Command was operating with a modest force for the land and air defense of Honshu, Shikoku, Kyushu, and the Izu Islands. The primary focus had been on building naval and air power for Operation Sho-Go. In Kyushu and southwestern Honshu, the Western District Army, led by Lieutenant-General Yokoyama Isamu, consisted of only the 86th Division and the 12th Air Division. Meanwhile, the Central District Army, commanded by Lieutenant-General Kawabe Masakazu in central Honshu and Shikoku, had the 44th and 73rd Divisions supported by the 11th Air Division. To the northeast, in Honshu and the Izu Islands, General Fujie Keisuke's Eastern District Army maintained the 72nd Division, along with both the 1st and 3rd Imperial Guards Divisions, the 66th and 67th Independent Mixed Brigades, and the 10th Air Division. Additionally, Lieutenant-General Uemura Toshimichi’s 36th Army was positioned as a mobile reserve in the Kanto and Shizuoka area, comprised of the 81st and 93rd Divisions, along with the 4th Tank Division. Further north, Lieutenant-General Higuchi Kiichiro’s 5th Area Army had deployed the 7th and 77th Divisions, the 1st Air Division, and the 12th Air Fleet stationed in Hokkaido. It also maintained a mixed brigade at Karafuto. Lieutenant-General Terakura Shozo commanded the 27th Army in the Kuril Islands, which included the 42nd and 91st Divisions, along with the 43rd and 69th Independent Mixed Brigades, and the 3rd and 4th Amphibious Brigades, as well as the Chishima 1st Brigade and Naval Base Force. The air situation was equally dire; Japan had only around 550 aircraft available for offensive operations and a total of about 770 aircraft and 1,200 anti-aircraft guns designated for defensive roles.

As preparations for Operation Ten-Go unfolded, the air and ground units in Japan underwent significant reorganization in February. This restructuring led to the formation of several military commands, including Admiral Ugaki's 5th Air Fleet based in Kyushu, Vice-Admiral Maeda Minoru's 10th Air Fleet in Kanto, Lieutenant-General Yoshimoto Teiichi’s 11th Area Army in northeast Honshu, derived from the now-defunct 27th Army, and additional area armies such as Fujie’s 12th in east-central Honshu, Lieutenant-General Okada Tasuku’s 13th in west-central Honshu, Kawabe’s 15th in western Honshu and Shikoku, and Yokoyama’s 16th in Kyushu. The reorganization of high-level military headquarters was not the sole initiative at this time. The Japanese Empire also approved a large-scale mobilization plan that called for the deployment of 42 divisions, 18 independent mixed brigades, and six tank brigades, amounting to approximately 1.5 million personnel. Following the fall of Iwo Jima and Okinawa, and with intelligence indicating that the Soviet Union was redeploying troops from the European theater to the Far East, Japan began preparing for the defense of its homeland.

This preparation involved activating the 1st and 2nd General Armies to replace the General Defense Command and implementing Operation Ketsu-Go. The strategy for Operation Ketsu-Go outlined that the Imperial Japanese Army would strive to defeat American forces while their invasion fleet remained at sea. The plan aimed to deliver a decisive blow against the American naval forces by first destroying as many aircraft carriers as possible, utilizing the special attack units from both the Air Force and Navy. As the amphibious forces approached the range of homeland airbases, the entire air combat strength would be deployed for continuous day and night assaults against these ships. The focus of these air operations was to disrupt American landing plans, targeting primarily troop and equipment transports. Should any American forces successfully land, these would be swiftly assaulted by the IJA to secure a decisive victory. The primary objective of the ground operation was to eliminate the American landing force right on the beach. Operation Ketsu-Go was designed as a comprehensive joint defense effort, mobilizing the full capabilities of the Army, Navy, and Air Force. The Navy's essential role was to protect the coasts by attacking invasion fleets using combined surface, submarine, and air forces. The Air General Army would closely coordinate with the Navy to locate and destroy American transports at sea. If the invasion forces succeeded in landing, the local Area Army would take command of all naval ground forces in its assigned territory and would exercise operational control over air units in support of the ground operations. A key component of the Ketsu-Go operational planning involved reinforcing sectors under attack by units transferred from other regions. Given that U.S. air raids had already severely impacted the transportation network, plans were made for troop movements to be conducted on foot. If the battle at the beach held no promise of a successful outcome, the conflict would inevitably shift to fighting inland. To prepare for this, interior resistance was planned. Guard units and Civilian Defense Corps personnel, along with elements of field forces serving as a nucleus, would be utilized as resistance troops. Their mission would involve attriting American forces through guerrilla warfare, espionage, deception, disruption of supply areas, and blockades as enemy landing forces advanced inland. This operation divided Japanese territory into seven zones, where air and naval special attack forces were directed to eliminate invading forces at sea and to establish an aggressive coastal defense. Field Marshal Sugiyama Hashime’s 1st General Army established its headquarters in Tokyo, assuming control over the 11th, 12th, and 13th Area Armies. Meanwhile, Field Marshal Hata Shunroku’s 2nd General Army set up its headquarters in Hiroshima, overseeing the 15th and 16th Area Armies. Additionally, to provide a cohesive command structure for all Army air units participating in the campaign, an Air General Army headquarters was formed under Kawabe. On the naval front, Admiral Toyoda took command of the General Navy Command, granting him supreme operational authority over all Navy surface and air forces.

In the coming months, the Japanese continued to prepare for the anticipated invasion by mobilizing new units and diverting existing forces from Manchuria and other regions. By August, Yoshimoto’s 11th Area Army had been reinforced to include seven infantry divisions and two infantry brigades. The 12th Area Army, now under General Tanaka Shizuichi, was significantly larger, comprising 20 infantry divisions, two tank divisions, eight infantry brigades, three tank brigades, three artillery brigades, and one anti-aircraft brigade. Okada’s 13th Area Army was organized with six infantry divisions, three infantry brigades, one tank brigade, one artillery brigade, and one anti-aircraft brigade. The 15th Area Army, under the command of Lieutenant-General Uchiyama Eitaro, was formed with eight infantry divisions, three infantry brigades, one artillery brigade, one anti-aircraft brigade, and two tank regiments. Yokoyama’s 16th Area Army included a substantial force of 15 infantry divisions, eight infantry brigades, three tank brigades, three artillery brigades, and one anti-aircraft brigade. Additionally, Higuchi’s 5th Area Army consisted of six infantry divisions and two infantry brigades.

In tandem with these ground preparations, Lieutenant-General Sugawara Michio’s 6th Air Army and Ugaki’s 5th Air Fleet were assigned the critical role of launching a powerful air counterattack against the American invasion fleet, targeting carriers, gunnery ships, and transport vessels. In conjunction with elements from the 1st Air Army, 5th Air Army, 3rd Air Fleet, and 10th Air Fleet, the Japanese strategy focused on executing strikes against US carriers. For this task, 330 IJNAF aircraft were specifically assigned. An additional 250 aircraft from both the IJAAF and IJNAF were designated to target gunnery ships, while transports would be subjected to round-the-clock suicide attacks over a span of 10 days. Various aircraft types,including trainers, transports, float planes, bombers, and obsolete fighters, would be used in kamikaze missions. The air assaults on the transports would also incorporate all available aircraft not assigned to other operational duties. Although Japanese fighters had limited effectiveness against B-29 raids, they were expected to inflict damage on the invasion fleet. It was essential, however, that IJAAF and IJNAF fighters first establish air superiority over the targeted areas. Achieving this goal was a questionable assumption, especially given the formidable strength of US air power. By the end of June, nearly 8,000 aircraft, predominantly kamikazes, had been assembled for what was expected to be a decisive battle, with an estimated additional 2,500 planes likely to be produced by the end of September. To enhance their efforts, Kaiten suicide midget submarines and various special attack units were also designated to target any invading fleet, underscoring the significance of suicide attacks in Japanese military strategy. The hope was that these suicide, or tokko, units would inflict a 30 to 50 percent loss on the invading forces. However, as of June 30, only 1,235 surface special-attack boats and 324 underwater types had been produced, significantly hampering Japan's preparations for the impending decisive battle.

In preparation for the seizure of Japan's industrial heart through an amphibious invasion, General MacArthur was laying the groundwork for a significant military operation. On April 3, the Joint Chiefs of Staff designated him as the Commander in Chief of the United States Army Forces in the Pacific. This appointment granted him administrative control over all Army resources in the Pacific, with the exceptions of the 20th Air Force, the Alaskan Command, and the Southeast Pacific forces. Additionally, all naval resources in the Pacific, except those in the Southeast Pacific Area, were placed under Admiral Nimitz's control, making them available for major operations against Japan. With the conclusion of the war in Europe, plans were proposed to redeploy 10 infantry divisions, 5 armored divisions, and 72 air groups to the Pacific. Consequently, the total forces in the Pacific were set to increase from approximately 1.4 million Army troops as of June 30 to nearly 2,439,400 by December 31. On June 2, the 20th Air Force was reorganized into the U.S. Army Strategic Air Force under General Carl Spaatz. This command would oversee the newly formed 20th Air Force led by Lieutenant-General Nathan Twinning, which had been reorganized from the 21st Bomber Command, and Lieutenant-General James Doolittle’s 8th Air Force, which was restructured from the 20th Bomber Command and slated for deployment in the Ryukyus. Simultaneously, MacArthur was developing plans for Operation Downfall, the ambitious strategy for invading Japan. This operation envisaged a massive offensive against the islands of Kyushu and Honshu, utilizing all available combined resources from the Army, Navy, and Air Forces.

The invasion plan consisted of two key operations: Operation Olympic and Operation Coronet. The American plan for the invasion of Kyushu focused on seizing only the southern part of the island, delineated by a line extending from Tsuno on the east coast to Sendai on the west. The 3,000 square miles included within this boundary were considered sufficient to provide the necessary air bases for short-range support in the final operations planned against the industrial centers of Honshu. Within the selected southern region for invasion, known as the "Olympic" plan, there were four lowland areas identified as suitable for the development of major airfields. The first area extended from Kagoshima, located on the western shore of Kagoshima Bay, through a narrow corridor to the Kushikino plain along the East China Sea. The second area ran northward from Shibushi on Ariake Bay, traversing a winding valley to Miyakonojo. The third area began at Kanoya, situated east of Kagoshima Bay, and followed the coastline of Ariake Bay. The fourth and largest area was located north of Miyazaki on the east coast.

Four months after American troops first landed on Kyushu, the next decisive amphibious operation against Japan was set to be launched. Code-named Coronet, this invasion targeted the Kanto Plain area of Honshu and was scheduled for March 1, 1945. The operation was tasked to two armies: the First and the Eighth, assigned to conduct a major assault against the heartland of Japan. Their immediate objective was to destroy all opposition and secure the Tokyo-Yokohama area. General MacArthur would personally command the landing forces and oversee ground operations on the mainland. Accompanying him would be the advance echelon of his General Headquarters, which would operate as the Army Group Headquarters in the field. The initial landings would involve 10 reinforced infantry divisions, 3 marine divisions, and 2 armored divisions. These forces, launched from the Philippines and Central Pacific bases, would be continuously protected by the ships and aircraft of the Pacific Fleet, alongside land-based air support. Thirty days after the initial assault, each army was set to be reinforced by a corps of 3 additional divisions. Five days following this reinforcement, an airborne division and an AFPAC Reserve Corps consisting of another 3 divisions would be made available. In total, these 25 divisions were tasked with seizing the Kanto Plain, including the general areas of Tokyo and Yokohama, and carrying out any further operations necessary to overcome Japanese resistance. The strategic reserve for the entire operation would comprise a corps of 3 divisions located in the Philippines, along with sufficient reinforcements from the United States, allowing for the deployment of 4 divisions per month.

For Operation Olympic, General Krueger’s 6th Army was appointed to lead the effort, employing a total of 14 divisions that were already positioned in the Pacific. Meanwhile, the 1st and 8th Armies were designated to conduct Operation Coronet, comprising a total of 25 divisions primarily sourced from the redeployment of troops and equipment from the European theater. Eichelberger’s 8th Army planned to land on Sagami Bay and subsequently fan out to secure the western shores of Tokyo Bay, reaching as far north as Yokohama. Concurrently, General Courtney Hodges’ 1st Army was set to land at the Kujukuri beaches, with the objective of pushing west and south to clear the eastern shores of both Tokyo and Sagami Bays. To mitigate the risks associated with landing on the heavily fortified and well-garrisoned islands of Japan, a comprehensive campaign of air-sea blockade and bombardment was advocated. 

The 20th Air Force, launching from bases in the Marianas and the Ryukyus, aimed to cripple Japan's industrial capacity by ruthlessly attacking factories and transportation systems. This steady assault from the massive B-29 bombers was expected to severely diminish Japan's ability to sustain its large military organization and effectively distribute its remaining power. Simultaneously, carrier task forces would conduct repeated raids on crucial coastal areas, targeting enemy naval and air forces, disrupting shore and sea communications, and supporting long-range bombers in their strikes against strategic objectives. The Far East Air Force, also based in the Ryukyus, would focus on selected targets intended to dismantle Japan's air capabilities both in the homeland and in nearby regions of North China and Korea. By intercepting shipping and shattering communication lines, the Far East Air Force aimed to complete the isolation of southern Kyushu, preparing it for an amphibious assault. As the target date approached, it was planned that these air raids would intensify, culminating in an all-out effort from X-10 to X-Day. In the final ten days before the landing phase, the combined bombing power of all available planes, both land-based and carrier-based, would be unleashed in a massive assault. The objectives included reducing enemy defenses, destroying remaining air forces, isolating the target area, and facilitating preliminary minesweeping and naval bombardment operations. The fortifications within the designated landing areas would be overwhelmed by tons of explosives, while naval vessels and engineering units worked to eliminate underwater mines and barriers. With such concentrated power backing them, it was anticipated that the amphibious forces would be able to execute their assault landings with minimal losses. This strategy aimed to minimize casualties, further diminish Japan's air capabilities, and cut off reinforcements from Asia. There was even a possibility that such measures could compel Japan to surrender, thus eliminating the need for a significant landing on the Home Islands. In a notable first, Admiral Spruance’s 5th Fleet and Admiral Halsey’s 3rd Fleet were to operate simultaneously. Admiral Spruance's fleet would focus on the landing operations, while Admiral Halsey’s fleet would provide strategic support through raids on Honshu and Hokkaido.

On July 28, the 16 fast carriers of Admiral McCain’s Task Force 38 and the four British carriers of Admiral Rawlings’ Task Force 37 commenced operations to weaken the air, naval, and shipping capabilities of the Home Islands. By mid-August, Vice-Admiral John Towers was assigned command of a reinforced Task Force 38, tasked with executing a series of strikes against Japan east of the 135th meridian, while General Kenney’s Ryukyus-based Far Eastern Air Forces targeted objectives to the west. Additionally, Rawlings’ Task Force 37, enhanced to nine carriers, launched diversionary strikes against Hong Kong and Canton. Starting on October 18, the 3rd Fleet began aggressive operations against aircraft, airfields, and shipping in Kyushu, Shikoku, and Honshu to isolate the assault area for the upcoming Kyushu invasion. Six days later, the Fast Carrier Task Force was divided into Task Force 38 and Task Force 58. Task Force 38 retained 12 fast carriers specifically for strikes against Japan. The pre-invasion air strikes, surface bombardments, and minesweeping operations in the Kyushu landing zones commenced, steadily increasing in intensity as they approached X-Day on November 1. The ten fast carriers of Vice-Admiral Frederick Sherman’s Task Force 58 would provide direct support for the Kyushu landings, which were to be conducted by Admiral Turner’s Task Force 40, consisting of 800 warships and 1,500 transports. In this effort, three Fire Support groups, each accompanied by an escort carrier group, would launch preemptive assaults on the designated Olympic landing zones. 

Off southeastern Kyushu’s Ariake Bay, Rear Admiral Richard Connolly's 3rd Fire Support Group (TG 41.3), comprising 6 old battleships, 6 cruisers, 13 destroyers, and 34 support craft, was tasked with eliminating coastal batteries at Toi Misaka, Hi Saki, and Ariake Bay. Additionally, they would target seaplane bases and suicide boat/submarine pens at Oshima, Odatsu, Biro Jima, and Sakida, followed by softening defenses at the XI Corps landing beaches. Meanwhile, approximately 30 miles north along Kyushu’s southeastern coast, Rear Admiral Ingolf Kiland’s 7th Fire Support Group (TG 41.7), consisting of 3 old battleships, 8 cruisers, 11 destroyers, and 35 support craft, would bombard coastal batteries, suicide-boat nests, and seaplane bases located at Tozaki Hana, Hososhima, and Miyazaki. This group would also destroy rail junctions at Tsumo Jogasaki and Tsuno to disrupt reinforcements heading south, before finally shelling the I Corps invasion beaches near Miyazaki. Off southwestern Kyushu, Rear Admiral Giraud Wright’s 5th Fire Support Group (TG 41.5), with 4 old battleships, 10 cruisers, 14 destroyers, and 74 support craft, was set to hammer fortifications within the Koshiki Retto and at the beaches between Kaminokawa and Kushikino. Their mission included knocking out Noma Misaki and Hashimi Saki coastal batteries, the Akune seaplane base, and Kushikino’s airfield, while also cutting the Akune–Kushikino road and rail lines. Ultimately, they would provide heavy fire support for the V Amphibious Corps landing beaches. Meanwhile, General Krueger planned to first secure Kagoshima and Ariake Bays as crucial ports of entry. Following that, the objective was to push inland as far as the Tsuno-Sendai line to block mountain defiles and prevent any enemy reinforcements from the north.

As a preliminary operation, on October 28, the reinforced 40th Division, now under Brigadier-General Donald Myers, was assigned to seize positions in the Koshiki Island group opposite Sendai. The objective was to establish emergency naval and seaplane bases on these islands while also clearing the sea routes to the coastal invasion area of Kushikino. The 40th Division was also tasked with making preliminary landings on the four islands of Tanega, Make, Take, and Lo off the southern tip of Kyushu, with the goal of safeguarding the passage of friendly shipping through the strategic Osumi Strait. On November 1, General Krueger's three main corps were set to conduct simultaneous assault landings in the designated objective areas. Major-General Harry Schmidt’s 5th Amphibious Corps would land near Kushikino, drive eastward to secure the western shore of Kagoshima Bay, and then turn north to block the movement of enemy reinforcements from upper Kyushu. Meanwhile, General Hall’s 11th Corps was to land at Ariake Bay, capture Kanoya, advance to the eastern shore of Kagoshima Bay, and then move northwestward to Miyakonojo. Following this, Swift’s 1st Corps would assault Miyazaki on the east coast, subsequently moving southwest to occupy Miyakonojo and clear the northern shore of Kagoshima Bay, thereby protecting the northeast flank. Additionally, Major-General Charles Ryder’s 9th Corps, initially held in reserve, was selected to execute a diversionary feint off the island of Shikoku while the other three assault corps advanced on the actual landing beaches. Finally, Krueger kept the 77th Division and the 11th Airborne Division in Area Reserve, prepared to follow up the invasion forces. Should these units prove insufficient to fulfill their assigned tasks, a buildup from units earmarked for Coronet would be initiated at a rate of three divisions per month.

On the other side, the Japanese anticipated that Kyushu would be the next target and identified the same beaches selected for Operation Olympic as the most likely landing sites. In response, Generals Hata and Yokoyama concentrated the formidable 57th Army under Lieutenant-General Nishihara Kanji around the areas of Ariake Bay and Miyazaki. Meanwhile, Lieutenant-General Nakazawa Mitsuo commanded the 40th Army, which was positioned in the Ijuin-Kagoshima sector to the west. Hata's mobile reserves were stationed near Mount Kurishima, consisting of at least five divisions and several independent brigades, prepared to swiftly engage enemy forces before they could establish secure beachheads. Although Yokoyama and Hata did not anticipate an invasion in northern and central Kyushu, they had many units distributed throughout the region. The Japanese government prioritized defensive preparations for Kyushu over those for Honshu, hoping that a fierce defense of Kyushu would deter American forces from attempting a similar operation on Honshu.

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General Krueger's forces tackled Japan's Shobu Group in Luzon, while preparing for Operation Downfall, the invasion of Japan itself. Despite tough terrain, American forces made significant gains, encircling the Japanese. Meanwhile, Japan readied for defense, mobilizing troops and launching air counterattacks. As the Allies pressed forward, the impending invasion loomed, with strategies developed to land on Kyushu and Honshu. Ultimately, intense battles shaped the eve of an operation that would determine the war’s fate and change history forever.