From the very beginning, preparations for the defense of the Homeland had been seriously hampered by enemy air activity over the home islands.1 Shortly after the Ketsu-Go plan had been issued, these attacks were intensified and rapidly reached a point at which they threatened to disintegrate the entire social and economic structure of the nation before the decisive battle could even be begun.
From the standpoint of physical destruction and suffering, the worst raids of all were the B-29 incendiary attacks against urban areas. During April, May, and June, the fire-bomb campaign against the large urban complexes was mercilessly continued. In June, it was extended to 12 small and medium-sized cities containing important basic materials and sub-contracting facilities.2 In some of the larger raids it was estimated that as many as 400 B-29's participated, while the monthly cumulative total of B-29 sorties rose by June to 3270.3
Carrier planes, as well as fighters and bombers from Okinawa and Iwo Jima also added weight to the attacks. Although these were mainly directed at airfields in Kyushu, urban areas as far east as Tokyo were harassed by strafing and bombing. Fighter and bomber sorties from Okinawa reached a monthly total of 777 by June and fighter sweeps from Iwo Jima 265 for the same period.4
The damage caused by these operations was almost incalculable. Large areas of the three urban complexes forming the keystones of Japan's war economy were laid waste, 56% of the Tokyo-Kawasaki-Yokohama area, 52% of Nagoya, and 57% of Osaka-Kobe being burned out causing complete paralysis of production, transportation, and communications facilities. Key industrial installations in the smaller cities were also levelled. Harbors and channels all along the Japan Sea and the Inland
Sea were tightly sealed with aerial mines for days at a time. It became almost impossible to move material or commodities either from the continent or between ports in Japan itself.5
By the end of June, about 118,000 citizens in the three major urban areas had met with violent and painful deaths, about 170,000 were wounded and missing, about 1,300,000 buildings had been destroyed, and a total of 5,503,000 persons, about 42% of the population of Japan's three largest urban areas had been bereft of their homes, furniture, clothing, and personal effects.6
These violent assaults on the very foundations of urban society were rapidly reflected in the morale, efficiency, and availability of the labor force. The attacks so aggravated the already precarious food situation and created such a critical shortage of housing that millions were forced to flee to the countryside to seek the very necessities of life. In Tokyo-Kawasaki-Yokohama, for example, 4,210,000 people, about 53% of the population evacuated, leaving the remains of their homes and their means of livelihood behind. Throughout the nation more than 8,000,000 persons did likewise, meaning that almost 10% of the national citizenry became displaced persons.7
The mass evacuations greatly compounded the effects of the air raids on productive capacity. Immediately following the raids, an absentee rate of 70-80% was noted, dropping to about 40% after the restoration of local order. Even in those factory districts not damaged, the rate was about 15%. This high rate of worker absenteeism was an important factor in the decline of industrial productivity.8
The evacuations were symptomatic of the steady disintegration of organized urban life. Against the overpowering enemy air offensive the people and their local officials were beginning to feel completely helpless. The entire system of air raid precautions simply collapsed under the unexpectedly heavy assault. Shelters proved insufficient in number and vulnerable to enemy bombs, fire-fighting equipment was entirely inadequate to cope with the cascade of incendiaries, and the welfare, medical, and rehabilitation programs were over-saturated by the flood of casualties and
Although the dislocation of urban society was bad enough, a much more serious long-term result of the air raids was their effect on the industrial plant of the nation. Prior to April, the submarine and mine blockade, combined with the air attacks of November 1944 through March 1945, had carried forward apace the disintegration of Japanese basic industry which had begun early in 1944.10 During the spring and early summer, this process assumed alarming proportions.
The most critical shortage continued to be that of coal. By June 1945, the imports of heavy coking coal from North China had ceased, crippling heavy industry. Although the domestic production of coal held up fairly well,11 it proved to be almost impossible to move it in any appreciable amount due to the submarine and mine blockade of the major ports.12
The coal shortage fell most heavily on the iron and steel, non-ferrous metals, cement, and chemicals industries. By the end of June, the production of ferrous metals (iron, steel, and carbon steel had fallen to a mere 35% of the wartime peak. Cement production was down to 46% of the peak figure.13 The situation was no better in critical non-ferrous metals, with copper, aluminum, and magnesium standing at a bare 35% of the industry's peak, and in one case, that of aluminum, sagging to a disastrous 16%.14
The chemicals industry, like the others, was
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hard hit by shortages of raw materials, a special problem being the scarcity of salt.15 In the case of five selected chemical products (ammonia, nitric acid, caustic soda, benzol, and toluol) total production in the quarter ending in June 1945 was only 43% of the same period in 1944.16 The most important immediate effect of the collapse of the chemicals industry was on the production of explosives. The gross production of propellants, high explosives, and primer materials in June 1945 was only 62% of the peak established in March 1944.17 This made it exceedingly difficult for the Japanese to meet the ammunition production program laid down to support decisive battle plans.
From the standpoint of decisive battle planning, the most dangerous basic material shortage was that of oil.18 By the end of June, the quarterly gross national production and import of crude and refined petroleum had fallen to 24% of the wartime peak established in the period July-September 1943, and the inventory of 4,751,000 barrels was only about 8% of what had been on hand at the beginning of the war.19 Of this, only about 606,000 barrels were aviation gasoline, of which 333,900 barrels were earmarked for decisive battle operations.
Despite a reduction in operations to within 80% of expectations, including rigid curtailment of training flights and elimination of all operational flights except those connected with the continued prosecution of Ten-Go,20 consumption still ran about 188,600 barrels in June against a production of about 98,000 barrels.21 Although aviation gasoline was to be supplemented by alcohol and other substitute fuels, the projected margin between requirements and
inventories was so exceedingly narrow that, particularly if the enemy continued to bomb refineries and tank farms, it was doubtful whether the decisive air battle could be fought later than the end of 1945.22
By the end of June, the decline of basic industry had not yet had its full impact on the fabricating industries of Japan. Although they were producing substantially less than they had at peak output, it was felt that the majority of decisive battle needs could be met by the estimated time of invasion. Aircraft production held up best of all, a total of 4,856 aircraft of all types being manufactured in the quarter ending in June. This was 65% of the wartime peak rate.23
The munitions industry was, at this time, somewhat less well off than aircraft, and the production goals set to support decisive battle plans seemed beyond reach in most items.24 This industry had reached its peak in the period October-December 1944 and thereafter fell off mainly as a result of raw material shortages. By the end of June 1945, Army ordnance industries were producing at a rate of only about 44% of peak and Navy facilities at about 55%.25
The shipping industry was also caught in the vicious circle of raw material shortages and high attrition through losses.26 By the end of June, 79% of all Japan's merchant tonnage had been sunk. Shipyards were producing a bare 27% of the wartime peak set in January-March 1944. Maritime shipping capacity was down to 850,000 gross tons and was dropping at the rate of 2,300,000 tons per month. In the quarter just ended cargo loading amounted to 2,968,400 tons or roughly 27 % of wartime peak maritime activity. The shipping crisis was severe enough to dash any hope that industry could even be partially revived through efforts to improve the raw material situation.27
The blockade and the air raids had the same
impact on the service industries as elsewhere. Of these, by far the most important was food. Before the war, Japan imported about 20% of her most important staple, rice, from Korea, Formosa, and the southern area. The shipping shortage had reduced this to a trickle, no rice at all being imported from the southern area after March 1944. The ambitious program of subsisting the nation on continental imports, which had been laid down in January 1945,28 fell far short, only 60% of the quota being met in the quarter January-March and even less by June. Moreover, rice for the Armed Forces had been withdrawn in ever increasing quantities so that, by 1945, there was on the average 40% less rice for civilian consumers than had been the case in 1941. An even worse situation obtained in the case of soy beans, meat, fish, vegetables and salt.29
As a result of the dwindling inventories of basic foods, the daily ration amounted to fewer than 1,500 calories, about 65% of the minimum Japanese standard for the maintenance of health and work efficiency.30 While this was not actually a starvation diet, the prospect of the tightening of the blockade plus attacks on Japan's land transportation system, and the possibility of attacks on the unharvested fields themselves all gave rise to a distinct danger of famine, at least in the more densely populated areas.
Even more frightening was the possibility that the U. S. invasion might be so long postponed that the troops disposed for decisive battle would run through their reserve rations. This was one more reason why an invasion in the fall was to be preferred if Japan were to strike the heavy counter-blow which she was so carefully planning.31
As enemy air raids hammered away at the threadbare fabric of Japan's industrial economy, preparations for the decisive battle were carried resolutely forward. In a series of orders issued during the first week in April, Imperial General Headquarters set in motion the second mobilization of ground troops according to plan.32 Six new Army headquarters,33 eight line combat
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Concurrently with this second phase mobilization, the planned diversion of troop units from Manchuria was executed.38 The 1st Armored Division began to arrive in the Thirty-sixth Army zone in early April, closing into the new position before the end of the month. The 25th and 57th Divisions, scheduled for assignment to Sixteenth Area Army and Thirty-sixth Army, respectively, arrived in Kyushu by mid-May, while the 11th Division displaced into the Fifteenth Area Army zone in southern Shikoku in early May.39 Although not called for in the original plan, the 8th Tank Brigade was also included in the redeployment and joined the Thirteenth Area Army in the Tokai district of central Honshu.40
The High Command had meanwhile undertaken a reexamination of the strategic situation in light of the increasingly unfavorable developments on Okinawa. By early May Imperial General Headquarters concluded that the enemy might soon be free to take the initiative
in the next major move and that Kyushu now appeared the more probable target, the earliest possible invasion date falling after late June.41
The possibility of an invasion two months earlier than previously estimated resulted in an immediate acceleration of the defensive preparations. The first move was the transfer, 1 May, of units from the less threatened northeastern flank of the Homeland, the 147th Division being diverted to Kanto from Hokkaido and the 3d Amphibious Brigade to southern Kyushu from the Kuriles.42
In view of the extremely remote probability of an enemy invasion of the northeastern area and of further contemplated withdrawals from this area, Imperial General Headquarters ordered the Fifth Area Army on 9 May to concentrate the bulk of its troops on Hokkaido, leaving garrisons to defend only the more important islands in the Kurile chain43 This new mission, in effect, ruled out possible activation of Kestu No. 1, and rendered any subsequent action in this area of a delaying nature rather than decisive.44
In the week which followed, the High Command further strengthened the defenses of Kyushu and its approaches with the assignment of two additional divisions and the activation of a new independent mixed brigade. The 57th Division just assembling at Hakata, Kyushu, en route from Manchuria to join the Thirty-sixth Army, was reassigned to the Sixteenth Area Army on 10 May.45 Four days later the 77th Division (Hokkaido) was transferred from the Fifth Area Army to Sixteenth Area Army while on the same day the lone infantry regiment securing the island of Tanegashima lying just South of Kyushu was reorganized as the 109th Independent Mixed Brigade.46
Concurrently with these steps taken by the High Command, the Second General Army Commander. Field Marshal Shunroku Hata, drafted an operational plan to meet the situation. This called for forces in Kyushu to wage a delaying action if the enemy should land during July, trading space for time until the assembly, equipping, and training of the decisive battle reserve could be completed and a general counteroffensive launched. Preparations for the delaying campaign in the critical invasion areas were to be completed by the end
While the mobilization and redeployment of ground troops was on schedule the preparation of battle positions in the critical invasion areas was falling seriously behind. Although the troops were assisted by thousands of civilian volunteers, by early May the construction of coastal positions in Kyushu had barely begun. The 86th Division and the 98th Independent Mixed Brigade, garrisoning the Ariake Bay area, had brought their field fortifications to about 50% completion, while the 156th Division on the Miyazaki coast, the 146th Division on the Satsuma peninsula, and the 145th Division in the Fukuoka area were only 10-20% finished. Troops in all these units were in a low state of training,48 headquarters command arrangements were inadequate, and weapons, ammunition, equipment, and horses were still in short supply.49 In the Kanto district, an even worse situation obtained.50 There were permanent coast defense batteries in the entrance to Tokyo Bay and a few scattered semi-permanent heavy artillery positions forming the nuclei of projected strongpoints, but an effective field fortification system did not as yet exist.51
More discouraging than the lag in field construction was the extent to which local commanders misunderstood the policy of aggressive beach defense and failed properly to indoctrinate their subordinates.52 Based largely on precedents set in the southern area, many coastal combat units located their rallying positions much too far from the beach. Although this was an understandable attempt to avoid the devastating effects of enemy naval bombardment, it had the highly undesirable
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effect of allowing the enemy to seize and consolidate a sizeable beachhead, which was entirely contrary to Ketsu-Go doctrine. Line combat divisions of the decisive battle reserve were also establishing their concentration points too far inland.
These discrepancies were uncovered during May by staff officers of Imperial General Headquarters while inspecting the critical invasion areas. Immediate remedial action was clearly indicated. On 6 June, therefore, the Army Section of Imperial General Headquarters issued a new manual of decisive battle tactics. This document contained an even stronger statement of the aggressive beach defense doctrine than had been laid down in the Ketsu-Go plan and its implementing directives. At the same time, the Chief of the Army General Staff, General Yoshijiro Umezu, drew up a detailed explanation of the desires of the High Command and disseminated it to all units. Pursuant to these instructions, the Commanders-in-Chief of the First and Second General Army immediately initiated strong orientation and indoctrination programs in their respective areas. However, much valuable time had already been lost.53
The lag in the construction of coastal positions, the costly misunderstandings concerning tactical doctrine, and the difficulties of redeployment and training were especially dangerous in Kyushu since it was earliest on the estimated invasion schedule. To help meet the situation, Marshal Hata, in late May forwarded a strong recommendation to Imperial General Headquarters that the forces scheduled for redeployment to Kyushu under the Ketsu-Go plan be moved immediately without waiting for activation of the operation.54 The High Command, however, was so worried about the dangers inherent in what they felt to be a premature weakening of the Kanto district that no action was taken on this recommendation.55
While the major ground commands were engaged in these preparations, Imperial General Headquarters took steps to ready the Army air establishment for the decisive battle. On 8 May, orders were issued releasing the Second Air Army in Manchuria from the order of battle of the Kwantung Army, the Fifth Air Army in China from the China Expeditionary Army, and the 1st Air Division in the Northeast area from Fifth Area Army. All these forces were assigned to the Air General Army.56
On the same day, the High Command issued a directive outlining the air redeployment plan for Ketsu-Go. The essentials of this document were as follows:57
By late May, it had become apparent to the Army High Command that further pursuance of the Ten-Go operation would result in a needless expenditure of air strength without appreciably delaying the enemy in his final approach to the Homeland.58 On 26 May, therefore, orders were issued releasing the Sixth Air Army from attachment to Combined Fleet and reverting it to control of the Air General Army. At the same time, General Masakazu Kawabe, Commander-in-Chief of Air General Army, was given a directive concerning his immediate mission, the gist of which was as follows:59
The most serious operational problem facing the Japanese remained that of air defense. In the struggle to provide an antidote to the violent enemy air offensive, the nation was handicapped by many adverse circumstances. In the first place, having lost the Marianas and Iwo Jima, and with Okinawa already being used as a forward base, the Japanese were deprived of patrol and reconnaissance bases so necessary to the maintenance of an adequate warning network. Moreover, the enemy, using these same bases was now able to mount fighter-escorted bombing attacks over almost all of the Homeland. Another serious handicap was the chronic shortage of antiaircraft guns and ammunition, brought about mainly through the decline in production of these items. Finally, it was found that even those guns that were available were ineffective against night attacks by high-altitude planes.60
In the face of these obstacles, both the Army and the Navy undertook to reorganize, strengthen, and redeploy air defense forces. In
the case of ground units, this involved the conversion of several antiaircraft groups and units into antiaircraft divisions, at the same time strengthening each of the newly organized units.61 Some of the batteries were redeployed from the large urban areas to smaller cities and to key positions on railroads and harbors.62The organization of interceptor units remained as before although the shortage of aircraft continued due to the higher priority enjoyed by the offensive air establishment.63
The trend of Navy action in the matter of air defense had been towards achieving independence from Army control. As enemy carrier task forces maneuvered closer and closer to the Homeland, the distinction between interception and offensive operations tended to break down. The Navy accordingly decided to organize its own interceptor pools in the various Homeland areas. On the 23d, the 71st and 72d Air Flotillas were activated under Third and Fifth Air Fleets, respectively, to take charge of interception in eastern and western Honshu, Shikoku, and Kyushu.64 Together, the Army and Navy were able to muster about 970 aircraft for air defense purposes.65
By the beginning of June, the Homeland defense situation, as well as developments in other theaters, had reached a point where even a greater mobilization of national effort was considered an essential prerequisite to waging a successful decisive battle. With military preparations rapidly passing from the planning stage, the High Command concluded that it was now necessary to strengthen still further the all-out effort by drawing in the Government as well as the military. On 8 June, therefore, a conference attended by members of the Supreme War Direction Council and other high officials of the Government was held in the Imperial presence. At this gathering a basic war policy was adopted which called for the full participation of the entire nation in prosecuting the war to the end.66
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Pursuant to the decisions of the Imperial conference, the Government on 23 June promulgated the National Volunteer Service Act, which, together with its implementing directives, contained the following general provisions:67
In the meantime, Imperial General Headquarters had taken steps to effect the third mobilization of ground combat units almost two months earlier than originally planned.68 Pursuant to a series of organization orders, the first of which was issued on 23 May, four new Army headquarters,69 10 coastal combat divisions,70 eight line combat divisions,71 and 14 independent mixed brigades were activated in the Homeland72 and on 19 June, assigned as follows:73
With these activations, the line strength of the Homeland defense armies (including Hokkaido) was brought to 30 line combat divisions,76 24 coastal combat divisions, two armored divisions, seven a tank brigades, 23 independent mixed brigades, and three infantry brigades.77
Concurrently with the implementation of the third mobilization, a further redeployment of major combat units was effected. The Fifth Area Army transferred the 42d Division and Chishima ist Brigade from the Kurile Islands to Hokkaido while at the same time the High Command ordered the transfer of the 4th Amphibious Brigade from the Kuriles to the Twelfth Area Army.78 In addition, the 209th Division was transferred from Thirteenth Area
Army to Thirty-sixth Army, further strengthening this large reserve Army to a total of six line combat and two armored divisions.79
By this time, production trends clearly indicated that industry was incapable of adequately supporting the immense structure of the Homeland defense forces and the tactical and strategic plans devised for their use. The priority enjoyed by the units in Kyushu was draining off almost all of the material strength of the military establishment. While this meant that preparations for the decisive battle in Kyushu would be almost certainly completed, it also meant that Kyushu would very likely be the only area in which a decisive battle could be supported at all.
The brightest spot in the otherwise clouded production picture was in aircraft. By the end of June, almost 8,000 planes, mostly tokko types, had been hoarded for the decisive battle, while it was fairly certain that an additional 2,500 could be produced by the end of September.80 Although this program was running slightly behind the schedule laid down in February,81 it remained a single encouraging item in an atmosphere of disaster. Facilities for basing this vast special-attack armada were also being rushed to completion. A total of 325 airstrips, some of which were simple one way strips, were under construction throughout the Homeland, 95 of them on secret sites far in the interior.82
Although doing fairly well in aircraft, the Japanese were far behind schedule in ground combat ordnance. At the end of June, output in every item was short of the schedule that had been set earlier in the year. Percentages of scheduled production actually achieved by this time were as follows:83
This discouraging situation in weapons production naturally made it very difficult to equip new units and almost impossible to achieve adequate levels in reserve dumps. The bulk of production was channeled to units in Kyushu and it was felt that at least sufficient weapons would be available to fight the decisive battle in that area by September.
Another bad situation facing the Japanese at this time was the extent to which preparations for naval surface participation in the Ketsu-Go were falling behind. In the quarter ending 30 June, only 1,235 surface special-attack boats had been produced and only 324 underwater types.84 These were 18% and 15% respectively of the targets set for September. While it seemed hardly likely that these goals could be met, as in the case of ordnance, it was felt that sufficient quantities would be available to fight the Kyushu decisive battle at least.
The failure of production efforts, coupled with transportation and communications difficulties, shortages of fuel and rations, and continued enemy air attacks had, by the end of June, dealt serious blows to the national preparations for decisive battle. As far as organization of units was concerned, there were few difficulties. In both Kyushu and Kanto, units of the third mobilization were expected to be fully organized, although untrained, by mid July. In Kyushu, 60% of these had already begun their training.85
Equipment, however, was another story. In Kanto, units of the third mobilization were short in every item, with no prospect of catching up as long as Kyushu held a higher priority. This was particularly true of small arms, anti-tank guns, mortars, and self-propelled cannon. Even in Kyushu, stocks of equipment on hand were only about 50% of third mobilization requirements with 31 August as the tentative completion date.86
Stockpiling of expendables was also in a confused state. In Kanto, no munitions and ordnance stockpiles had been established at all, while rations stocking was about 50% complete. Units in Kyushu, however, had built ammunition stockpiles to 100% of Ketsu-Go requirements, fuel to 94%, and rations to 164%.87 This was encouraging as regards the conduct of the Kyushu battle, but pointed up the fact that the national war potential was
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probably incapable of supporting more than one such decisive operation.
While preparations in the Homeland went slowly forward, the Okinawa campaign was brought to its unhappy end. The superhuman courage of the vastly outnumbered ground and naval forces and the expenditure of 2258 aircraft had completely failed to halt enemy seizure and consolidation of this most vital base.88 Organized resistance by Thirty-second Army ceased on 23 June89 and on the 25th the painful fact of Okinawa's loss was made known to the general public.90
Okinawa was but one strand in the web of disaster in which the Japanese were now caught. The pattern was repeated in the Philippines with the fall of Baguio and the virtual end of strategic delaying operations in Luzon, in the southern area where Allied landings at Brunei Bay, North Borneo and other points cut Japanese remnants to ribbons, in southeast Asia with the loss of Rangoon, and finally in Europe where the unconditional surrender of Germany had released millions of troops for redeployment against Japan Against this background, President Truman on 2 June made public the basic strategy to be used in the invasion of Japan, an operation that could not now be far off.91
Being inferior in the technical equipment of war and having been forced into an extremely disadvantageous strategic position, Japan's principal hope of success in the forthcoming Homeland battle lay in outguessing the enemy in accurately predicting the time and place of the invasion and meeting it with overwhelming force.
Quick formulation of a strategic estimate was, however, rendered impossible by the existence within Imperial General Headquarters of a wide range of opinion on every aspect of the problem. The only point on which there
was general agreement was that the enemy would immediately intensify the sea and air blockade of Japan and would sooner or later attempt an invasion.
The most important of the controversial issues was whether the United States would seek an early end to the war by moving immediately, or, on the other hand, initiate a long blockade designed to reduce Japan to the point of complete helplessness.92 A dominant majority adhered to the former alternative, and it became the official position of Imperial General Headquarters.93
Proceeding on the assumption that United States policy would call for a quick decisive battle, there were two possibilities regarding the direction and objective of enemy operations. First of all, the United States might seek an immediate decision by moving directly to the main Japanese islands. In this case, the enemy might first seize air and sea bases in such areas as the northern Ryukyus and the Izu Island chain lying between Tokyo and the northern Bonins. He would most certainly drop such plans, however, and move at once against the main Japanese islands if he ever became convinced that Japanese air power had completely collapsed.
On the other hand, with Japan Proper as the ultimate goal, the enemy might first seize additional major advance bases.94 A part of the Army intelligence staff in Imperial General Headquarters, particularly those officers connected with Chinese intelligence, was convinced that the United States forces would land in central and/or north China in order to give military support to the Chungking regime. Other groups within the headquarters, particu larly in the Army operations group, held that two strong additional possibilities were an invasion of southern Korea or of Saishu (Quelpart) Island lying in the key Korea Strait area. Any of these three would gain important advance bases, would cut Japan's continental supply lines, and, in the first two cases, would check Soviet influence in north China and Korea.
These possibilities were the subject of discussion in the High Command, with the majority opinion adhering to the view that the northern Ryukyus were the most probable target with Quelpart as a possible secondary invasion area.95
Following these preliminary operations, the enemy was expected to move as soon as possible against Japan Proper. In this connection, there were two possibilities considered, the first being a direct move to the Kanto district, and the other a campaign to gain air and sea bases in Kyushu and Shikoku first, followed by an advance on Kanto. While there was considerable anxiety over the possibility of a direct attack on Kanto,96 a great majority of the officers in Imperial General Headquarters agreed that the invasion of Kyushu seemed most probable.97 In any case, the consensus was that, so long as Japan was resolved to resist to the end, the final battle would be on the plains of Kanto, since it was not only the political and strategic center of the nation, but also the most favorable area for the deployment of enemy armored and mechanized equipment.
The various opinions concerning enemy capabilities and intentions were contained in formal estimates, memoranda, and other communications that circulated in High Command circles from May to July. Each idea was considered for acceptance or rejection by the Chiefs of the Army and Navy General Staff. No written estimate, however, was ever produced representing the combined opinion of the highest command levels. The study and circulation of the basic documents resulted, nevertheless, in the formulation of an official position that represented a blend of all the accepted recommendations and provided a firm basis for future action. A detailed summary of the final estimate is as follows:98
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On 5 July, the Navy Section of the High Command formally abandoned its concept of the decisive air battle over the East China Sea, the Ten-Go air operation having long since deteriorated into a series of small scale hit-and-run raids.104 The way was now clear to the formulation of a joint Army-Navy Air Agreement for the Ketsu-Go operation, an annex that had long been missing from the basic plan.
This agreement was issued to the field on 13 July, its basic features being as follows:105
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Tables appended to this agreement indicated in detail the desired deployment of all available air strength.
As the summer wore on, many complex planning difficulties arose in high-level Japanese headquarters, the most important of which was brought about by the shift of operational emphasis to Kyushu. It was feared that the high priority accorded to preparations in the south would so drain off field engineering supplies, ammunition, food, fuel and lubricants, and all other classes of military supplies that it would be impossible to conduct properly the defense of Kanto should that area be attacked directly before the end of the year.
A second source of anxiety to the High Command were the shortcomings of Japanese strategic intelligence. This was largely a result of the drying up of the major sources of information. With both air and sea superiority lost right up to the very shores of Japan itself, direct and frequent observation of enemy invasion bases by Japanese submarines and planes was impossible. The High Command was forced to rely almost entirely on radio intelligence, although this means was not completely reliable, and certainly not so in determining absolutely the direction, time, and strength of the attack. This inability to get sufficient warning naturally compounded the anxiety that was being felt about Kanto.109
In addition to these worries, the month of July found Imperial General Headquarters increasingly concerned about the possibility of an enemy landing in the Tokai (Nagoya) district of central Honshu. From the very beginning, the High Command had believed in the remote possibility that this area would be selected as a target.110 This feeling now became particularly strong in view of the fact that the Tokai district was the narrowest part of Honshu, that its defenses were relatively weak, and that with both Kyushu and Kanto becoming stronger day by day, it might tempt the enemy to cut Japan in two by landing in the vicinity of Ise Bay and occupy the areas around Nagoya, Kyoto, and Osaka. On 20 July, a staff group from Imperial General Headquarters held a special meeting in Kyoto to discuss countermeasures.111
A fourth troublesome problem faced by the High Command was the weakness of the defenses of Manchuria, northern Korea and Karafuto. Despite indications that the Soviet Union was on the verge of commencing hostilities against Japan, the Kwantung Army, already weakened by the withdrawal of troops and munitions for the Philippines, Formosa, and Okinawa, had been further reduced by the diversion of four crack divisions to the Homeland.112 Having decided on all-out commitment against the forthcoming American invasion attempt, there was little that Imperial General Headquarters could do about this particular problem except hope that the Japanese units could hold off the Soviet tide while a decision was being sought in the Homeland.113
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Still another problem which caused considerable concern within the High Command was the critically weak coastal defenses along the Japan Sea side of the Homeland. Recognizing that Japanese sea and air forces could not deny the enemy use of the vital Korea Strait, Imperial General Headquarters and Second General Army took some steps during July to strengthen the defenses along the coast of western Honshu.114 This flank, nevertheless, remained extremely vulnerable.
Far more serious than even these strategic planning problems was the extent of the damage inflicted on Japan by enemy aircraft during the month of July. After the devastation of March through June it seemed almost impossible that the American air offensive could gain in intensity. Such was far from the case. During the month, the Japanese counted a total of 20,859 sorties flown over the Homeland by enemy aircraft, more than four times as many as in any previous month. Only six days in the month were free of air raids of any kind, and on one day (28 July) more than 3,400 sorties were flown.115
During July, B-29 operations against the Homeland were expanded about 25%. Abandoning the offensive against large urban areas, the enemy concentrated his July attacks against 35 small and medium-sized cities, each of which received more than 100 tons of bombs, mostly incendiaries, and fourteen of which received more than 1,000 tons.116 At the same time, the aerial mining campaign against Japan's coastal waterways was continued.
During the same period, other enemy air forces were far from idle. Okinawa-based bombers and fighters swarmed all over southern Japan piling up a total of 3,193 sorties, almost four times as many as in June. Fighters based on Iwo Jima, operating mainly over the Kanto, the Osaka-Kobe, and Nagoya areas, flew 1,787 sorties, almost seven times as many as in the previous month. Both these short-range air forces hammered air bases, shipping factories, railroads, tactical positions, and even fishing villages throughout all of Japan west of Tokyo. Air reconnaissance activities over Kyushu, Shikoku, and Kanto were even more pronounced than in June.
About 10 July, the American carrier task force appeared again, hitting targets throughout Japan, but concentrating on Hokkaido and northeastern Honshu. These atttacks, directed mainly against airfields, shipping, industrial targets, and transportation, added up to a total for the month of 12,213 sorties.117
Urban area incendiary raids continued to cause the deepest and most lasting damage to the Japanese war potential. Large sections of the cities which contained some of Japan's most vital fabricating and sub-contracting facilities lay in smouldering ruins.118 Next in importance were the enemy carrier task force
raids. Vital steel production facilities at Ishin omaki, Kamaishi, and Wanishi were heavily damaged in these operations. Widespread havoc was wrought in the ports of Aomori and Hakodate, the most serious loss being the putting out of action of every single one of the rail ferries plying between Hokkaido and Honshu. This cut rail haulage capacity between the two islands from 300,000 tons per month to almost zero. The carrier plane campaign against Japanese airfields throughout the Home Islands continued, interdicting many important installations and heavily damaging several.119
Even before the July raids, it had become obvious that an unchallenged continuation of such mass enemy air attacks would render Japan physically incapable of further resistance, particularly if the enemy shifted, as appeared likely, to attacks on the nation's land transport system and other tactical targets. To meet this situation, the High Command took a drastic step. On 30 June, Imperial General Headquarters ordered Air General Army to assume complete responsibility for carrying out a systematic air defense of the Homeland, simultaneously transferring the 10th, 11th and 12th Air Divisions, which had been engaged in air defense operations under the control of respective area armies, to the command of the Air General Army. This new mission represented a switch from the former policy of strict conservation of aircraft.
Operations were carried out during July but, in spite of the addition of eleven fighter regiments to the air defense forces,120 units were still so thinly spread and quick concentration was so difficult, that enemy air units continued to break through almost at will.121
In the midst of these discouraging planning
and operational setbacks, the only encouraging sign remained the fact that the forces on Kyushu were rapidly reaching a state of full combat readiness. Regardless of what appeared to be disaster for the Japanese nation, the High Command held firm in its resolve to fight the Kyushu battle as scheduled.122
The responsibility for preparing the ground defenses of Kyushu belonged to Field Marshal Shunroku Hata, Commander-in-Chief, Second General Army and, under him, to Lt. Gen. Isamu Yokoyama, Commander of Sixteenth Area Army. Pursuant to the basic Ketsu-Go plan, the headquarters of both these officers as well as the staffs of the local army commanders had undertaken to estimate the trend of future enemy tactics to be used against Kyushu. By early July, these efforts had resulted in a consensus of opinion which was substantially as follows:123
PLATE NO. 158
It was the Japanese intention to blunt the enemy invasion spearhead off Kyushu chiefly by an all-out attack of the air forces. Immediately available in western Japan for this purpose were units of the Sixth Air Army under Lt. Gen. Michio Sugawara and of Fifth Air Fleet under Vice Adm. Matome Ugaki. These were as follows:128
In addition, at the outset of the emergency in Kyushu, it was planned to deploy the following units into the area:129
In mid July the staff of Sixth Air Army and Fifth Air Fleet conducted a joint operational study in Fukuoka, and during the remainder of the month, both these headquarters perfected their operational plans. Combined and summarized, these plans provided as follows:130
Operating simultaneously with the air special-attack forces against the enemy were to be the sea tokko units. In the Kyushu and southern Shikoku area, these were as follows:131 (Plate No. 154)
Apart from the sea tokko effort, the naval surface forces were scheduled to play little part in the defense of Kyushu. Most of the vessels of 31st Destroyer Squadron (19 operational vessels in all) were to be used for lifting Kaiten (midget submarine) to the scene of action and for subsequent night action against transports. In consideration of the fuel problem, other gunnery ships were barred altogether from participation in the operations.133
Japan's hope of success in the battle for Kyushu depended almost entirely on the results expected from the air and surface special-attack operations. Even as early as June, the Navy had estimated that about 30-40% of the invading convoy could be sunk by the tokko attacks.134 As reports of the damage inflicted on the enemy off Okinawa in the Ten-Go operation became available for study,135 this estimate was raised to 30-50%. It was estimated that this would cost the enemy at least five assault divisions before the landing even began.136
PLATE NO. 159
Although this estimate of enemy losses was officially accepted by Imperial General Headquarters, the Army commanders responsible for the conduct of ground operations within the scope of Ketsu No. 6 recognized that these estimates were excessively high. It was felt that, in view of the difficult conditions under which the tokko operations would necessarily have to be conducted, a more realistic approach to the problem indicated a possible maximum loss to the enemy of 20% of the invasion fleet of transports or about three divisions.137
After receiving this initial setback at the hand of the tokko forces, the enemy was scheduled to meet with strong resistance on the ground from the very beginning of the landings. By the end of July, the tactical commander of ground forces on Kyushu, Lt. Gen. Yokoyama, had at his disposal 14 divisions, six independent mixed brigades, and three tank brigades.138 Although some of these units were still deficient in training, the equipping and deployment of troops were generally completed as was the operational stockpiling of munitions.139
The deployment of major units of Sixteenth Area Army was as follows:140 (Plate No. 159)
In general, the tactics to be used by the ground formations on Kyushu were based upon the concepts which had given rise to the coastal combat and line combat divisional organization.141 These principles applied both to local areas such as Ariake Bay (Plate No. 160), where strong coastal combat formations were backed up by local mobile reserves, and to Kyushu as a whole which was to receive reinforcements from Honshu under the Ketsu-Go plan.142
Salient features of the ground operational plans were as follows:143
PLATE NO. 160
Ground operations were expected to complete the destruction of enemy forces begun by the tokko units. It was estimated that the artillery and automatic weapons fire on landing craft, coupled with the fierce attacks of the coastal combat formations would reduce the remaining enemy force by 30-50%.144
If the losses sustained in the initial landing were as high as expected, the Japanese ground forces would be faced with no more than nine enemy divisions established ashore, of which only four or five would be located on the principal attack front. Available to cope with this remaining force was the Area Army mobile reserve of five divisions and three tank brigades soon to be reinforced by the arrival of four divisions from Honshu.145
While these estimates were being made and the summer wore on, combat preparations on Kyushu reached fruition. To Imperial General Headquarters it seemed that chances were steadily improving for dealing the enemy staggering losses if he chose to invade Kyushu.
In marked contrast to the favorable progress
being registered by Sixteenth Area Army, preparations in the Kanto area were moving ahead at a snail's pace.146 Responsibility for this sector fell to the First General Army, the top tactical command in northern Honshu, (Plate No. 161) and to its Twelfth Area Army, commanded by General Shizuichi Tanaka.
By the end of July, opinions advanced in various staff studies reflected a fairly well defined appraisal of the enemy's intentions in the event of a direct invasion of Kanto.147 It was believed that the preliminary operations, insofar as they concerned the tightening of the blockade around the Homeland and the pre-landing shelling and bombardment, would follow a pattern similar to that expected if the initial target proved to be Kyushu. Opinion as to other specific enemy intentions revolved around the following major points:148
Pursuant to the joint Army-Navy Air Agreement concluded during July the combined weight of all Army and Navy air forces was to be thrown into a gigantic, all-out aerial offensive over the Kanto area if Ketsu No. 3 were activated. Immediately available for this purpose were units of the First Air Army under Lt. Gen. Takeo Yasuda and of the Third Air Fleet under the command of Vice Adm. Kimpei Teraoka.150 In addition,, upon issuing an alert for the implementation of Ketsu No. 3, it was planned to deploy the remainder of the air units to fields from which they could support the decisive attacks.
By the end of July no operational plans for the coordinated commitment of these forces over Kanto were yet under consideration. The full energies of the staffs were still directed towards perfecting the plans to support Ketsu No. 6 operation which occupied top priority.151
In accordance with this same fundamental assumption, the bulk of the surface special-attack units were deployed in the Kyushu area. Only a small portion of these forces could be redeployed to the Kanto area if that proved to be the target of the initial invasion.152 Already deployed around Tokyo Bay, however, were the following naval surface special-attack forces under the command of Vice Adm. Michi taro Totsuka, Commander, Yokosuka Naval Station:153
With these relatively weak surface special-attack forces it was recognized that air and surface tokko operations against an initial enemy invasion in the Kanto area would not achieve the success hoped for in Ketsu No. 6 operations.
PLATE NO. 161
PLATE NO. 162
Nevertheless, it was felt that a sufficiently strong blow could be delivered to blunt seriously the enemy attack.
After penetrating this special-attack screen, the enemy would next encounter determined resistance from ground units at the very edge of the beach. By the end of the month, 11 line combat and seven coastal combat divisions,155 seven independent mixed brigades, two armored divisions and three tank brigades were available to General Tanaka, tactical commander of ground forces in the Kanto area.
Combat effectiveness of this vast force, however, was far below that of Sixteenth Area Army on Kyushu. Troops of the second mobilization were being issued the first of their equipment and were only beginning their training. Worse still, it would be the end of the year before equipping units of the third mobilization would be even generally completed. Despite these shortages, all units were being deployed to their assigned areas in order to begin defensive preparations. Accumulation of reserve supplies was even further behind schedule, with the prospect that Kyushu would continue to siphon off the total output of production until the latter part of August.156
Major units of the Twelfth Area Army were now deployed as follows:157
With regard to the deployment of these forces a somewhat different situation prevailed than was the case in Kyushu. The Twelfth Area Army's large central mobile reserve, the Thirty-sixth Army, permitted the Area Army to assign a greater portion of its strength farther forward. In each of the Fifty-first, Fifty-second and Fifty-third Armies, therefore, all of the line combat and coastal combat divisions were made responsible for a sector along the beaches, leaving in each Army only a tank brigade as mobile reserve.
Meanwhile, on the basis of the estimate that an initial invasion in the Kanto area would not begin until after fall, the same urgency for speedy preparation of operational plans did not obtain as was the case with the Second General Army. The First General Army, early in May, had therefore ordered the Twelfth Area Army to continue the operational policy then in force while the General Army undertook a more thorough and deliberate study of preliminary drafts covering plans for the employment of these ground forces.160
This prolonged study culminated in the publication, 17 July, of the First General Army operational plan.161 On the same day a conference attended by the chiefs-of-staff of the component Area Armies was convened at the General Army headquarters in Tokyo to discuss the more important details. Shortly thereafter, Twelfth Area Army published its own operational plan based upon the General Army plan. Summarized and combined, the essential features of these two plans included the following:162
As of the end of July no conclusions had yet been reached regarding the expected results of each phase of operations against an enemy landing in the Kanto area. It was still too early to accurately predict the defensive poten-
PLATE NO. 163
tial of the Twelfth Area Army as it would exist by late fall. Much remained to be accomplished before the defenses would give cause for the same optimism which prevailed in the case of Kyushu.
While the High Command was thus pushing final preparations for the defense of Kyushu and the First General Army, anticipating scarcely a trickle of supplies until the requirements of the Kyushu area were completely satisfied, was placing primary emphasis on the construction of coastal fortifications and training of newly mobilized units, the progressively worsening strategic situation made it appear doubtful whether any of these preparations would be tested in battle.
In the first place, the terrific aerial bombardment to which the Homeland had been subjected during July showed no evidence of abating.164 Although the casualties were now less than in the earlier, giant fire bomb raids on the larger complexes,165 the disruptive effects were being spread over a wider segment of urban society. The cumulative total of bombs which had been dropped on the four main islands by the end of July had risen to over 130,200 tons of which more than 98% had been directed at 98 urban areas or precision targets within these areas.166
Of greatest concern within the High Command was the paralysis spreading at an accelerated rate throughout the Japanese industrial plant. Output of the basic industries continued to decline during July, primarily because of the rapid drying-up of raw material stockpiles although enemy air attacks were contributing to the lowered production to an increasing extent because of plant destruction, transportation dislocations and the increase in absenteeism among the labor force.167
Concurrently, the impact of this decline,
added to the cumulative effects of the widespread urban air raids, began to be felt more keenly in the fabricating industries where production levels had previously remained relatively high. Aircraft production, for example, which during the early summer months had held up well, fell off to 62% of the average monthly rate of the preceding quarter.168 Only 1,003 planes of all types were completed.169 The planned production goal of 16,000 by September 30 was now clearly beyond the capabilities of the industry. Even worse, to forestall the possibility of further attrition, flight operations, which already were proving ineffective, would have to be further restricted, leaving the enemy practically unopposed in the air.170
The munitions industry fell even further behind the established quotas, although production of light artillery had spurted during the month.171 Percentages of scheduled production actually achieved by the end of July were as follows:172
In both construction and hauling capacity, the shipping industry was by now approaching a state of complete collapse. Monthly production of new bottoms had established a new low, falling off to about 15,500 tons or less than 10% of the peak monthly average established in January-March 1944. An additional 4% of merchant tonnage had been sunk, bringing the total losses to 83%.173 Maritime shipping capacity at the end of the month was down to 780,000 tons, most of which continued to operate in the Japan Sea between Korea and the Homeland.174 One net effect of this attrition
was the virtual suspension of the vitally important inter-island traffic except for small vessels of less than 200 tons.175
In the case of oil, one of the most critical items in the decisive battle plans, the outlook appeared even more ominous. Consumption during the month of about 155,390 barrels, had further reduced the stockpile of aviation gasoline to 508,160 barrels, of which 333,900 barrels were now earmarked for decisive battle operations. Production from all sources had declined sharply during July to 60,890 barrels.176
Even rail movements were falling off sharply, although the railroad network had not yet been singled out for intensive attacks except in the case of the Hokkaido-Honshu ferry system and a few isolated bridges.177 The carrying capacity was now reduced to 8,724,165 tons as compared with the peak monthly average of 14,849,749 tons during 1943.178 Moreover, temporary delays due to the heavy urban raids were becoming more general and shipment of many critical items was falling far behind schedule.
Nor was there any cause for optimism in the High Command regarding the over-all situation now existing in the Allied camp. Almost three months had elapsed since the collapse of Germany-three months for the enemy to lay the ground-work and begin the stupendous task of transfering overwhelming ground, air and sea forces to the Pacific theater. It was estimated that if the U.S.S.R. joined the attack against Japan in August or September, there would be available in the eastern provinces 40-50 divisions, 6-7,000 aircraft and 4,000 tanks.179
Such was the situation facing the nation as the hot and humid month of August ushered in the most critical period in Japan's history. In spite of the odds building up against them, the Japanese people well knew that if their leaders were determined to carry out the decisive battle on the sacred soil of the Homeland there was no alternative but to fight to the bitter end.