Battle of Okinawa went on for so long that they concluded the Allies would not be able to launch another operation before the
typhoon season, during which the weather would be too risky for amphibious operations. Japanese intelligence predicted fairly closely where the invasion would take place: southern Kyūshū at Miyazaki, Ariake Bay and/or the
Satsuma Peninsula.
While Japan no longer had a realistic prospect of winning the war, Japan's leaders believed they could make the cost of invading and occupying the Home Islands too high for the Allies to accept, which would lead to some sort of armistice rather than total defeat. The Japanese plan for defeating the invasion was called Operation Ketsugō (決号作戦, ketsugō sakusen) ("Operation Codename Decisive"). The Japanese planned to commit the entire population of Japan to resisting the invasion, and from June 1945 onward, a propaganda campaign calling for "The Glorious Death of One Hundred Million" commenced. The main message of "The Glorious Death of One Hundred Million" campaign was that it was "glorious" to die for the holy emperor of Japan, and every Japanese man, woman, and child should die for the Emperor when the Allies arrived. While this was not realistic, both American and Japanese officers at the time predicted a Japanese death toll in the millions. From the Battle of Saipan onward, Japanese propaganda intensified the glory of patriotic death and depicted the Americans as merciless "white devils". During the Battle of Okinawa, Japanese officers had ordered civilians unable to fight to commit suicide rather than fall into American hands, and all available evidence suggests the same orders would have been given in the home islands. The Japanese were secretly armistice rather than total defeat. The Japanese plan for defeating the invasion was called Operation Ketsugō (決号作戦, ketsugō sakusen) ("Operation Codename Decisive"). The Japanese planned to commit the entire population of Japan to resisting the invasion, and from June 1945 onward, a propaganda campaign calling for "The Glorious Death of One Hundred Million" commenced. The main message of "The Glorious Death of One Hundred Million" campaign was that it was "glorious" to die for the holy emperor of Japan, and every Japanese man, woman, and child should die for the Emperor when the Allies arrived. While this was not realistic, both American and Japanese officers at the time predicted a Japanese death toll in the millions. From the Battle of Saipan onward, Japanese propaganda intensified the glory of patriotic death and depicted the Americans as merciless "white devils". During the Battle of Okinawa, Japanese officers had ordered civilians unable to fight to commit suicide rather than fall into American hands, and all available evidence suggests the same orders would have been given in the home islands. The Japanese were secretly constructing an underground headquarters in Matsushiro, Nagano Prefecture, to shelter the Emperor and the Imperial General Staff during an invasion. In planning for Operation Ketsugo, IGHQ overestimated the strength of the invading forces: while the Allied invasion plan called for as many as 54 divisions (14 for Olympic and 38–40 for Coronet), the Japanese expected up to 90.[34]
Admiral Matome Ugaki was recalled to Japan in February 1945 and given command of the Fifth Air Fleet on Kyūshū. The Fifth Air Fleet was assigned the task of kamikaze attacks against ships involved in the invasion of Okinawa, Operation Ten-Go, and began training pilots and assembling aircraft for the defense of Kyūshū, the first invasion target.
The Japanese defense relied heavily on kamikaze planes. In addition to fighters and bombers, they reassigned almost all of their trainers for the mission. More than 10,000 aircraft were ready for use in July (with more by October), as well as hundreds of newly built small suicide boats to attack Allied ships offshore.
Up to 2,000 kamikaze planes launched attacks during the Battle of Okinawa, achieving approximately one hit per nine attacks. At Kyūshū, because of the more favorable circumstances (such as terrain that would reduce the Allies' radar advantage), they hoped to raise that to one for six by overwhelming the US defenses with large numbers of kamikaze attacks within a period of hours. The Japanese estimated that the planes would sink more than 400 ships; since they were training the pilots to target transports rather than carriers and destroyers, the casualties would be disproportionately greater than at Okinawa. One staff study estimated that the kamikazes could destroy a third to half of the invasion force before landing.
Admiral Ernest King, the C-in-C of the U.S Navy, was so concerned about losses from kamikaze attacks that he and other senior naval officers argued for cancelling Operation Downfall, and instead continuing the fire-bombing campaign against Japanese cities and the blockade of food and supplies until the Japanese surrendered. However, General George Marshall argued that forcing surrender this way might take several years, if ever. Accordingly, Marshall and Knox concluded the Americans would have to invade Japan to end the war, regardless of casualties.
Despite the shattering damage it had absorbed by this stage of the war, the Imperial Japanese Navy, by then organized under the Navy General Command, was determined to inflict as much damage on the Allies as possible. Remaining major warships numbered four battleships (all damaged), five damaged aircraft carriers, two cruisers, 23 destroyers, and 46 submarines.[53] However, the IJN lacked enough fuel for further sorties by its capital ships, planning instead to use their anti-aircraft firepower to defend naval installations while docked in port.[53] Despite its inability to conduct large-scale fleet operations, the IJN still maintained a fleet of thousands of warplanes and possessed nearly 2 million personnel in the Home Islands, ensuring it a large role in the coming defensive operation.
In addition, Japan had about 100 Kōryū-class midget submarines, 300 smaller Kōryū-class midget submarines, 300 smaller Kairyū-class midget submarines, 120 Kaiten manned torpedoes,[53] and 2,412 Shin'yō suicide motorboats.[54] Unlike the larger ships, these, together with the destroyers and fleet submarines, were expected to see extensive action defending the shores, with a view to destroying about 60 Allied transports.[55]
The Navy trained a unit of frogmen to serve as suicide bombers, the Fukuryu. They were to be armed with contact-fuzed mines, and to dive under landing craft and blow them up. An inventory of mines was anchored to the sea bottom off each potential invasion beach for their use by the suicide divers, with up to 10,000 mines planned. Some 1,200 suicide divers had been trained before the Japanese surrender.[56][57]
The two defensive options against amphibious invasion are strong defense of the beaches and defence in depth. Early in the war (such as at Tarawa), the Japanese employed strong defenses on the beaches with little or no manpower in reserve, but this tactic proved vulnerable to pre-invasion shore bombardment. Later at Peleliu, Iwo Jima, and Okinawa, they switched strategies and dug in their forces in the most defensible terrain.[citation needed]
For the defense of Kyūshū, the Japanese took an intermediate posture, with the bulk of their defensive forces a few kilometers inland, back far enough to avoid complete exposure to naval bombardment, but close enough that the Americans could not establish a secure foothold before engaging them. The counteroffensive for
For the defense of Kyūshū, the Japanese took an intermediate posture, with the bulk of their defensive forces a few kilometers inland, back far enough to avoid complete exposure to naval bombardment, but close enough that the Americans could not establish a secure foothold before engaging them. The counteroffensive forces were still farther back, prepared to move against the largest landing.[citation needed]
In March 1945, there was only one combat division in Kyūshū. Over the next four months, the Imperial Japanese Army transferred forces from Manchuria, Korea, and northern Japan, while raising other forces in place. By August, they had 14 divisions and various smaller formations, including three tank brigades, for a total of 900,000 men. Although the Japanese were able to muster new soldiers, equipping them was more difficult. By August, the Japanese Army had the equivalent of 65 divisions in the homeland but only enough equipment for 40 and ammunition for 30.
The Japanese did not formally decide to stake everything on the outcome of the Battle of Kyūshū, but they concentrated their assets to such a degree that there would be little left in reserve. By one estimate, the forces in Kyūshū had 40% of all the ammunition in the Home Islands.
In addition, the Japanese had organized the Volunteer Fighting Corps, which included all healthy men aged 15 to 60 and women 17 to 40 for a total of 28 million people, for combat support and, later, combat jobs. Weapons, training and uniforms were generally lacking: many were armed with nothing better than antiquated firearms, molotov cocktails, longbows, swords, knives, bamboo or wooden spears, and even clubs and truncheons: they were expected to make do with what they had. One mobilized high school girl, Yukiko Kasai, found herself issued an awl and told, "Even killing one American soldier will do. ... You must aim for the abdomen." They were expected to serve as a "second defense line" during the Allied invasion, and to conduct guerrilla warfare in urban areas and mountains.
The Japanese command intended to organize its Army personnel according to the following plan:[64]
Total mobilized: 3,150,000
Kyushu – 900,000
Kanto (Tokyo) – 950,000
Korea – 247,000
For the Decisive Battle
Kyushu – 990,000
Kanto – 1,280,000
Fifth Air Force
Tiger Force
Combined Fleet
First Air Army
Third Air Fleet
Third Fleet
Tiger Force
Battle of Okinawa
