As early as January 1945, the Imperial Japanese Army and Navy reached agreement (although their cooperation was, as always, limited by inter-service rivalry) on Ketsu-Go (“Operation Decision”): the final defence of the Japanese home islands against Allied invasion. A single phrase from the Precepts Concerning the Decisive Battle issued on 8 April 1945 by Gen Korechika Anami, Minister of War, will serve to illustrate these measures: all ranks were exhorted to “possess a deep-seated spirit of ramming”. General Yoshijiro Umezu, Army Chief of Staff, emphasized that “the certain way to victory… lies in making everything on Imperial soil contribute to the war effort … combining the total material and spiritual strength of the nation …” Servicemen and civilians alike were left in no doubt that the final defence would be to the death; that all available weapons would be used suicidally.

Meeting the Invasion Armada

Imperial General HQ believed (rightly) that an Allied invasion would be directed first against southern Kyushu and, once a beachhead was established there, against the Tokyo area, southeast Honshu.

Since the IJN was now almost bereft of surface striking units, the first line of defence against the invasion armada would be provided by the remaining aircraft for which pilots and fuel were available – some 10,700 according to USSBS figures – of the Army and Navy. Half of these, 2,700 of the IJN and 2,650 of the IJA, would be kamikaze.

Both the IJN and IJA sought to strengthen the kamikaze units and to impose some unity of aircraft types within them by producing purpose-designed suicide planes, of which the IJN’s Yokosuka D4Y4 Model 43 and Aichi M6A1 are described in Chapter 4. The IJN’s other major attempt at a “special attack” bomber, intended to be cheaply and quickly manufactured from non-strategic material, was the wooden-construction Yokosuka D3Y2-K (finally redesignated D5Y1). The programme was initiated in January 1945 and was aimed at a production target of 30 per month, but not even a prototype was completed.

The IJA had more success, in terms of production only, with its Nakajima Ki-115 Tsurugi (“Sabre”). This cheap and simply-produced suicide bomber was built largely of metal, with a wood-and-fabric tail assembly and, being intended only for one-way missions, with a jettisonable undercarriage. The open- cockpit aircraft was theoretically suitable to be flown by a pilot with only basic training, but not surprisingly in view of the speed of the development programme (design began on 20 January 1945; the prototype flew only seven weeks later) it proved a beast to handle, especially during takeoff on its unsprung undercarriage, which had to be modified. Of the 105 examples completed by the war’s end, none was operational. No examples were completed of an improved model, the Nakajima Ki-230, or of the Showa Toka (“Wistaria”), a copy of the Ki-115 for the IJN.

Kamikaze and conventional air strikes, coordinated with suicidal attacks by the IJN’s 45 remaining fleet submarines, would begin when the invasion armada was within c.180 miles (290km) of the Kyushu beaches. As the armada drew nearer, the rate of attack would increase, with troop transports the primary targets, until, off the beaches, all remaining aircraft would be committed to a non-stop mass suicide assault which, it was estimated, could be sustained for up to 10 days. At this time, the kamikaze would be supplemented by a “banzai charge” by the IJN’s remaining surface units – only 2 cruisers and 23 destroyers remained fully operational in August 1945 – midget submarines, human torpedoes and explosive motorboats.

Ambitious building programmes for small “special attack” craft were severely limited by material and power shortages caused by blockade and strategic bombing. Thus, by August 1945, there were available in the home islands only 100 koryu five-man submarines; 300 kairyu two-man submarines; 120 shore-based kaiten human-torpedoes; and about 4,000 shinyo and maru-ni EMBs. With the exception of the comparatively long-ranging koryu, these small suicide craft were deployed in well-concealed bases in southern and eastern Kyushu and southern Shikoku. The major locations were: in Kyushu, Kagoshima (20 kairyu, 500 shinyo), Aburatsu (20 kairyu, 34 kaiten, 125 shinyo), Hososhima (ZO kairyu, 12 kaiten, 325 shinyo) and Saeki (20 kairyu); in Shikoku, Sukumo (12 kairyu, 14 kaiten, 50 shinyo) and Sunosaki (12 kairyu, 24 kaiten, 175 shinyo). The IJA’s

EMBs were similarly but separately dispersed. In addition, 180 kairyu, 36 kaiten and 775 shinyo were deployed around Sagami Wan to defend the Tokyo area of Honshu. More shinyo and maru-ni (perhaps as many as 1,000 of each type) remained at bases in Korea, Formosa, Hainan Island, North Borneo, Hong Kong and Singapore.

“Fukuryu”: the Suicide Frogmen

It was estimated that the mass onslaught would destroy some 35–50 per cent of the Allied armada before any troops could be put ashore. Offshore, a last line of maritime defence would be provided by the least-known of the “special attack” forces: the demolition frogmen called fukuryu (“crouching dragons”).

Their training had begun at Kawatana in November 1944 (see here), although the IJN had employed teams of swimmers on hazardous missions since early in the war; notably at Hong Kong, where skindivers defuzed Allied mines to prepare a way for landing craft. A Japanese prisoner taken at Peleliu, Palaus, late in 1944, claimed that he belonged to a 22-strong Kaiyu unit of swimmers trained to attack landing craft. Each swimmer was armed with three grenades, a knife and a simple demolition charge: a wooden box of c.160in3 (2620cm3) packed with trinitrophenol (Lyddite) with a fuze cut to the required length. But the kaiyu units, credited with damaging an LCI in the Palaus and a DE and an attack transport at Okinawa, were surface swimmers rather than frogmen.

The fukuryu appear never to have been deployed outside the home islands. Their role in the final defence would have been suicidal – as was, to some extent, their training. Their equipment – a loosely-fitting wet suit; a clumsy helmet not unlike that of a deep-sea diver; bulky air circulation and purification tanks strapped to chest and back and linked by a tangle of hoses – was most unsatisfactory. “There were very many [fatal] accidents during the training of fukuryu”, a Japanese veteran told me, “because the twin-tank oxygen re-breathing equipment was no good – but nothing better was available”. Nevertheless, some 1,200 fukuryu graduated from Kawatana and Yokosuka Mine School by the war’s end, when 2,800 were still in training.

To destroy inshore landing craft, each fukuryu was armed with a 22lb (10kg) impact-fuzed charge, incorporating a flotation tank, mounted on a stout pole (much like the anti-tank “lunge mine” described above). If his equipment functioned perfectly, the frogman could stay at an optimum depth of 50ft (15m) for up to 10 hours, sustained by a container of liquid food. Construction was begun of underwater pillboxes, concrete with steel doors, in which fukuryu would shelter from a pre-landing bombardment while awaiting their opportunity to sally forth and thrust their explosive lances against the bottoms of landing craft.

The fukuryu would form part of a network of beach defence. Farthest from the beach were moored mines, electrically detonated from ashore; then three lines of fukuryu deployed so that each man guarded an area of c.470sq yds (390sq m); then lines of magnetic mines; and finally beach mines. Capt K. Shintani, commanding the fukuryu, was somewhat optimistic in hoping that his men might “cause as much damage as the kamikaze aircraft”.

“Special Motorboats”: Amphibious Tanks

Attacks by fukuryu on landing craft might have been supported by the few completed Toku 4-Shiki Naikatei (“Type 4 Special Motor boat”; called the katsu) which, in spite of its designation, was an amphibious AFV. Originally designed by Mitsubishi for the IJN as a troop, weapon or freight carrier with a capacity of c.10 tons, the katsu was adapted early in 1944 to serve as a coast defence craft. Only 18 examples of this tracked amphibian were built.

The katsu’s 240bhp diesel engine gave a maximum land speed of c.15mph (24kmh) or, driving retractable twin propellers, a water speed of c.4.5kt (5mph, 9kmh). The craft displaced c.20 tons (20.3 tonnes) and was 36ft (11m) long overall, 10.8ft (3.3m) in beam, and of 7.5ft (2.3m) draught from track-base to deck-level. It mounted two 13mm MGs in shielded positions forward and carried two 17.7in (450mm) torpedoes in launching racks to port and starboard at deck level. The engine was within a pressurized compartment so that the katsu might be carried on the casing of a submerged submarine; but a wild scheme – Tatsumaki-Go (“Operation Tornado”) – to transport katsu in this way to Bougainville, in mid-1944, for an attack on offshore shipping, was abandoned, as were plans for their deployment at Peleliu and Saipan. They were held at Kure for possible employment in the final defence. They were slow, noisy and unhandy.

“Operation Olympic”: the Invasion of Kyushu

Operations “Olympic” (later re-named “Majestic”, but rarely known thus), the invasion of southern Kyushu scheduled to begin on 1 November 1945, and “Coronet”, the Honshu landings planned for 1 March 1946, would have been the largest amphibious operations of all time. The US 3rd Fleet (covering force) and 5th Fleet (amphibious force) would employ more than 3,000 warships and attack transports, excluding inshore landing boats. Anglo-American naval strength in the Pacific in August 1945 included approximately 30 fleet carriers, 78 escort carriers, 29 battleships, more than 50 cruisers and 300 destroyers, and close on 3,000 large landing craft.

Landings on Kyushu would be made by LtGen Walter Krueger’s 6th Army, of three Marine divisions, one armoured division and nine infantry divisions. And although General Marshall, US Army Chief of Staff, feared that “Downfall” (ie, both “Olympic” and “Coronet”) would cost at least 250,000 US casualties, a US War Department study of June 1945 predicted that the initial, critical, 30-day phase of “Olympic” should involve only c.30–35,000 casualties.

The Japanese hoped to destroy up to 50 per cent of the invasion force before it hit the beaches. And whatever proportion succeeded in landing would be opposed à outrance at the water’s edge. Imperial General HQ reasoned that only if the first of the amphibious assaults was bloodily repulsed might the Allies be brought to moderate their demand for unconditional surrender. All Japan’s limited resources must be devoted to this “decisive battle”, with little or nothing in reserve to counter later landings. Field-Marshal Hajime Sugiyama, overall commander of the final defence, 1st General Army HQ, Tokyo, decreed in mid- July: “The key to final victory lies in destroying the enemy at the water’s edge, while his landings are still in progress”.

In the summer of 1945, Japan had about 6 million men under arms, of whom some two-thirds were in isolated island garrisons, in Korea, or with the Kwantung Army in China-Manchuria, where a Soviet offensive might be expected. Regular Army forces in the home islands totalled c.2,350,000, with about 3 million Army and Navy auxiliaries (labour battalions and the like). FM Shunroku Hata’s 2nd General Army, with its HQ at Hiroshima, was responsible for Ketsu-Go Area No 6, embracing Kyushu, Shikoku and west Honshu; within this zone, the vital area of southern Kyushu was covered by the 14 infantry divisions and two armoured brigades (their AFVs near-immobilized by lack of fuel) of LtGen Isamu Yokoyama’s 16th Area Army.

Every man of military capability had now been drafted, but many newly-raised units consisted of ill- trained troops without adequate armament and sometimes even without full personal kit and uniforms. Transport was severely limited by a shortage of fuel, vehicles, mechanics, and even draught animals; communications were disrupted nationwide by the B-29 raids; and the paucity of adequate construction materials meant that beach defence works remained incomplete.

“One Hundred Million Will Die …!”

As early as 1944, Imperial General HQ had begun constructing a vast underground complex in the mountainous region of Matsushiro, central Honshu, with a similar refuge for Emperor Hirohito at nearby Nagano. While the great ones resisted to the last in this Japanese equivalent of Hitler’s mythical “Alpine Redoubt”, the ordinary civilians must emulate the aspirations (but not the almost non-existent exploits) of the German “Werewolf” guerrillas.

In November 1944, on pain of imprisonment in default, all Japanese male civilians between the ages of 14 and 61 and all unmarried females of 17–41 were ordered to register for national service as required. From this register, in June 1945, was drawn the Kokumin Giyu Sento-Tai (“National Volunteer Combat Force”), of ficially some 28 million strong. Cadres from Tokyo’s Nakano Gakko (“Army Intelligence School”) were sent throughout Japan – especially to Kyushu – to instruct this militia in the techniques of beach defence and guerrilla resistance, as laid down in the People’s Handbook of Resistance Combat.

Sustained by an individual ration of less than 1,300 calories daily – rice being often bulked out with sawdust or replaced by acorn flour – the unpaid militia, without uniforms but with armbands denoting combatant status, drilled with ancient rifles (one to every ten men); swords and bamboo spears; axes, sickles and other agricultural implements, and even long-bows, “effective at 50yds (45m)” according to the instruction manual. Empty bottles were collected to make “Molotov cocktails” and “poison grenades” filled with hydrocyanic acid; local craftsmen manufactured “lunge mines”, “satchel charges” and wooden, one- shot, black-powder mortars; and small-arms workshops, their labour forces decimated by dietary deficiency diseases, produced single-shot, smooth-bore muskets and crude pistols firing steel rods.

Those who lacked arms of any kind were told to cultivate the martial arts, judo and karate. Women were advised, with the endorsement of Empress Nagako, to wear mompei (the loosely-fitting pantaloons traditionally worn only by peasants working their fields), and were instructed on the efficacy of a kick to the testicles.

Thus, inspired by the spirit of the Special Attack Corps, the entire population of Japan stood ready to fight to the death. The slogan was displayed everywhere: “One Hundred Million Will Die for Emperor and Nation!”

The Last Kamikaze Hits

While most of Japan’s aircraft were reserved for use against an invasion fleet, a few kamikaze sorties continued to be made against Allied shipping in the Ryukyus. Most were flown by Shiragiku (“White Chrysanthemum”) units, so called because they were composed largely of venerable training aircraft; notably a purpose-modified kamikaze version of the IJN’s Kyushu K11W1/2 Shiragiku. IJA trainers such as the Kokusai Ki-86 (Allied codename “Cypress”), and Tachikawa Ki-9 (“Spruce”) and Ki-17 (“Cedar”), all three biplanes, took part in similar operations.

The last Allied warship sunk by a kamikaze aircraft fell victim to one of these veterans. From USN reports, which describe the attacker as a twin-float biplane of wood and fabric construction – and thus immune to proximity-fuzed shells – the aircraft that fell out of the sky over Okinawa at 0041 on 29 July 1945 to strike USS Callaghan was probably a Yokosuka K5Y2 (“Willow”). This flimsy machine, capable of only 132mph (212kmh) with a maximum bombload of 132lb (60kg), struck a ready-ammunition locker and triggered a chain of explosions and fires that sank the big destroyer, with 47 dead and 73 wounded, within 90 minutes. In a similar attack on the following night, another “sticks-and-string” kamikaze badly damaged USS Cassin Young.

It is generally accepted that the last Allied ship struck by a kamikaze aircraft was USS Borie (DD 704), damaged by the crash-dive of a lone “Val” while on radar picket duty for TF 38, as the carriers’ aircraft were launched off Honshu on 9 August. However, Inoguchi and Nakajima (see Bibliography) state that the attack transport USS La Grange was damaged by a kamikaze off Okinawa on 13 August. Also, it is possible that the Russian minesweeper T-152 (215 tons, 218 tonnes) was sunk by a kamikaze during Soviet landings on the northern Kuriles on 18–19 August, when a few suicide sorties are believed to have been flown by IJA aircraft from Shimushu Island.

“Body-Crashing”: the Ramming Interceptors

On 14 June 1944, Boeing B-29 Superfortresses struck for the first time at the Japanese home islands. Most early raids were made at high level (above c.30,000ft, 9150m), but although Japan’s air defence was deficient in both AA guns and aircraft with the speed and combat ceiling successfully to intercept the Superfortresses – of 414 B-29s lost, only 147 fell to Japanese interceptors or AA fire – it was felt that the results of such operations did not justify even the lowest loss rate.

Early in 1945, MajGen Curtis LeMay took over the Marianas-based 21st Bomber Command from BrigGen Haywood Hansell, adopting a policy of low-level incendiary raids at c.5–6,000ft (1500–1800m) by B-29s virtually unarmed for extra speed. By August, LeMay could claim that fire raids had completely shattered some 58 major cities and that by bombing alone Japan would soon be “beaten back into the dark ages”. Fire raids indeed caused far greater material and moral damage than the two atomic bombs: on 9–10 March, in a raid by 325 B-29s, 15.8 sq miles (41 sq km) of Tokyo were gutted and c.84,000 killed and more than 100,000 injured (compared to c.78,000 dead and 68,000 injured in the atomic blast at Hiroshima). In a fire raid on Toyama on 1–2 August, no less than 99.5 per cent of the city was devastated. And when Prince Konoye told the USSBS that the major factor in Japan’s decision to surrender was “fundamentally … the prolonged bombing by the B-29s”, he was speaking of the fire raids. One Japanese statesman, however, referred to the atomic destruction as “the big kamikaze that saved Japan”; meaning that the terrible civilian casualties sustained in just these two strikes afforded a decisive argument to the peace faction.

With fuel stocks low, factories and repair facilities dislocated, and many aircraft lacking trained pilots or held in reserve for the final kamikaze onslaught, the Japanese air arms proved unable to deal effectively with the low-level raiders and thus increasingly resorted to suicidal aerial ramming interceptions. Isolated instances had occurred earlier in the war. On 4 July 1942, Lt Mitsuo Suitsu, enraged when his naval air squadron’s field at Lae, New Guinea, was badly damaged by US bombers, fulfilled a vow of vengeance by destroying a Martin B-26 Marauder in a head-on collision with his Zero. The first Army pilot credited with such self-sacrifice was Sgt Oda who, also flying from New Guinea and unable to maintain the altitude conventionally to engage a B-17 that was “snooping” a Japanese supply convoy, brought down the Fortress by ramming with his Nakajima Ki-43 “Oscar”.

Tai-atari (“body-crashing”) tactics were not invariably fatal: a few US bombers were destroyed by Soviet-style Taran attacks, their tail assemblies chewed away by fighters with armoured propellers. USAAF personnel reported the first cases of what they judged to be deliberate ramming during a raid on the steel works at Yawata, Kyushu, on 20 August 1944. Of four bombers lost over the target area, one fell to AA, one to aerial gunfire, and two to a single Kawasaki Ki-45 Toryu (Dragon Killer; “Nick”): the “Nick” rammed one B-29 and the debris of the two aircraft brought down another.

In February 1945, an IJA manual stated that against B-29s (and the expected B-32 Dominators, of which only a handful became operational) “we can demand nothing better than crash tactics, ensuring the destruction of an enemy aircraft at one fell swoop … striking terror into his heart and rendering his powerfully armed planes valueless by the sacrifice of one of our fighters”. The manual noted that only partly trained pilots need be used and recommended as rammers the Nakajima Ki-44 Shoki (Demon; “Tojo”) and Kawasaki Ki-61 Hien (Swallow; “Tony”), on the dubious grounds that their designs gave the pilot a faint chance of baling out immediately before impact.

Earlier than this, in November 1944, the 2nd Air Army’s 47th Sentai formed the volunteer Shinten Sekutai squadron, dedicated to ramming attacks in “Tojos”. Their successes included the destruction of a B-29 over Sasebo on 21 November by Lt Mikihiko Sakamoto; another B-29 on 24 November (one of only two Superfortresses brought down in a 111-strong raid); and two B-29s (out of only six lost from a 172-strong force over Tokyo) on 25 February 1945. Fighters of the Kwantung Army also adopted ramming tactics, bringing down two B-29s over the Mukden aircraft works on 7 December 1944 and another on 21 December. On both occasions, Japanese aircraft also attempted air-to-air bombing, releasing time-fuzed phosphorus bombs above the US formations. At least one B-29 was destroyed by this method, which was also used in the defence of the homeland.

A less extreme measure than ramming was the formation at Matsuyama NAFB, Shikoku, in January 1945 of a fighter wing led by Capt Minoru Genda and including Saburo Sakai and other “aces”. Flying the Kawanishi N1K2-J Shiden (Violet Lightning: “George”) – probably Japan’s best interceptor; only c.350 were built – they achieved especially good results against Allied carrier strikes. On 16 February, WO Kinsuke Muto was credited with engaging single-handed 12 F6F Hellcats from USS Bennington over Atsugi, Tokyo, shooting down four and driving off the rest.

Attempted Aid from Germany

Unable to produce in sufficient quantity such advanced interceptors as the Kawasaki Ki-100 (396 of all models built), the Kawasaki Ki-102 (“Randy”; 238 built) and the Mitsubishi A7M3-J Reppu (Hurricane; “Sam”; prototype only), or to bring to operational status the Funryu (“Raging Dragon”) surface-to-air guided missiles, Japan sought German aid. Plans, and in some cases completed models, were acquired of the Bachem Natter, the Reichenberg piloted-bomb (built as the Baika), and the Messerschmitt Me 262 twin-engined jet fighter-bomber. A prototype based on the latter, the IJN’s Nakajima Kikka (“Orange Blossom”), flew on 7 August 1945; if production had been attained it was to have been deployed in concealed revetements as a “special attack” bomber.

A major effort at a point-defence interceptor was the joint IJN/IJA project for the Mitsubishi J8M1 (Navy) or Ki-200/202 (Army) Shusui (“Swinging Sword”), a near-identical version of the Luftwaffe’s Messerschmitt Me 163 Komet. Rights to produce a version of the Komet’s airframe and Walter HWK 509A bi-propellant (T-Stoff and C-Stoff, which the Japanese called Ko and Otsu liquids respectively) rocket engine, with a completed example of the aircraft itself, were purchased as early as March 1944; but only one Walter unit and an incomplete set of blueprints reached Japan. Germany’s final effort to provide her ally with more material on the Komet and other “special weapons” was made on 2 May 1945, when U.234 (Cdr Johann Fehler) sailed from Norway for Japan with high-ranking Luftwaffe officers, technicians, and two Japanese scientists aboard. En route, Fehler received the news of Germany’s collapse and, as he headed for the USA to surrender his boat, both Japanese committed seppuku.

In Japan, training with the Komet-replica MXY8 Akigusa (“Autumn Grass”) glider began in December 1944. The first powered flight was attempted on 7 July 1945 at Yokoku airfield, Yokosuka. Successfully jettisoning the takeoff trolley, LtCdr Toyohiko Inuzuka had reached c.1,300ft (400m) when, probably because of a fuel line blockage caused by the steep climb, the engine flamed out and the Shusui stalled and crashed, mortally injuring Inuzuka. Later that month, an explosion of the volatile fuel mixture during ground testing killed another of the project’s officers. Many similar fatalities – especially during the hard skid-landings that often brought the liquid propellants violently together – had occurred in Germany, where the “Devil’s Egg” was regarded by many Luftwaffe personnel as semi-suicidal at best.

The Japanese rocket interceptor differed little from its German pattern. The J8M1 had a span of 31.2ft (9.5m), a length of 19.86ft (6.05m) and a height on its jettisonable trolley of 8.86ft (2.7m). Powered by a Toko Ro.2 motor giving 3,307lb (1500kg) thrust for up to c.5.3 minutes, it was estimated to be capable of a maximum 559mph (900kmh) at 32,810ft (10,000m); thus probably having a range at optimum flight profile of less than 60 miles (96km). Its armament was to be two wing-mounted 30mm cannon – although if the planned production of more than 1,000 examples by August 1945 had been achieved, it is likely that many would have been expended in ramming attacks after exhausting their ammunition of 50 rounds per gun. In the event, only seven Shusui, which were to have been operated by the 312th Naval Air Group, were completed by the war’s end.

Forlorn Hope – Suicide Weapon