Kawasaki Ki-45 Toryu

The Ki 45 was Japan’s first twin-engine fighter and its most successful night fighter. It also served capably in a variety of missions, including ground attack, antishipping, and kamikaze.

The Kawasaki Ki-45 required more time to develop and place in service than almost every other Japanese warplane of World War II. By 1937 the notion of long-range strategic fighters, capable of escorting bomber fleets to targets and back, was becoming prevalent. Germany began successfully experimenting with its Messerschmitt Bf 110, which prompted the Imperial Japanese Army to adopt similar craft. That year it invited several companies into a competition, and Kawasaki, after many trials and prototypes, originated the Ki 45 Toryu (Dragon Slayer). This was a handsome, low-wing design with a pointed nose and a long, tandem cabin housing pilot and gunner. Initial flights revealed that the craft was underpowered, so a succession of better engines ensued until the Nakajima Ha–25 was utilized. Other problems centered around the landing gear, which were weak and hand-cranked in flight. With better motors and powered undercarriage, the Ki 45 showed promise, so in 1941 it entered production. A total of 1,701 were ultimately built, and they received the code name Nick during World War II.

Takeo Doi, chief project engineer, began work on this design in January 1938 but the first production aircraft did not fly combat until the fall of 1942. When it finally entered service, the Ki-45 soon became popular with flight crews who used it primarily for attacking ground targets and ships including U. S. Navy Patrol Torpedo (P. T.) boats. The Toryu was also the only Japanese Army night fighter to see action during the war.

The Japanese did not develop a dedicated single-engined ground support aircraft; the Japanese army relied on light bombers, such as the Ki-30 (‘Ann’), Ki-32 (‘Mary’), Ki-36 (‘Ida’) and Ki-51 (‘Sonia’). These were all obsolescent. However, the Kawasaki Ki-45-KAI Toryu (‘Nick’), although primarily designed as a twin-engined long-range fighter, turned out to be a quite useful attack aircraft. The Ki-45-KAIb version was armed with a 37 mm Type 98 tank gun, which fired the same ammunition as the Type 94 anti-tank gun (not to be confused with the less powerful Type 94 tank gun). The Type 98 was manually loaded. The Ki-45-KAIc instead carried a 37 mm Ho-203, less powerful than the Type 98 but equipped with a 15-round belt feed. The Ho-203 was later scaled up to the Ho-401 57 mm cannon, and this weapon (with 17 rounds) was installed in the attack version of the Ki-102 (‘Randy’) fighter, the successor of the Ki-45. Of this Ki-102b (also known as the Army Type 4 Assault Aircraft) about 200 seem to have been completed. The Ho-401 with its 520 m/s muzzle velocity was a suitable weapon for use against soft targets, but not much use against armour. Rikugun, the army aeronautical research institute, designed the Ki-93 with the Ho-402 in a belly fairing; this was also a 57 mm weapon but much larger and more powerful, firing its projectiles at 700 m/s. However, only one Ki-93 was ever flown. These Japanese aircraft were no longer as unprotected as most Japanese combat aircraft had been at the start of the conflict, but they were not heavily armoured either, the designers’ priorities being performance and handling.

Japanese strategists observed the Americans and the Europeans design and build a number of twin-engine, two-seat, heavy fighters during the mid- and late 1930s. The Japanese Army needed a long-range fighter to cover great distances during any large-scale conflict in the Pacific and army planners felt that a twin-engine design could meet this need. In March 1937, the Japanese Army Staff sent a rather vague specification for such an airplane to a number of manufacturers. Kawasaki, Nakajima, and Mitsubishi responded, but the latter two dropped out of the competition to concentrate on other projects. Between October and December 1937, the army amended the specification with additional information and directed Kawasaki to begin the design work. The specification described a two-seat fighter with a speed of 540 kph (336 mph), an operating altitude of 2-5,000 m (6,560-16,405 ft), and endurance of over 5 hours. The army chose the Bristol Mercury engine, built under license, to power the new aircraft.

In January 1939, Kawasaki rolled out the first prototype but initial flight tests did not impress. The airplane was too slow to meet the army speed requirement, and it suffered mechanical problems with the landing gear and engines. Top speed remained a problem, despite major changes on the second prototype, and the army put the project on hold. In April 1940, Kawasaki substituted 14-cylinder Nakajima engines, rated at 1000 horsepower each, for the original 9-cylinder motors rated at 820 horsepower each. Engineer Doi also revised the engine nacelles and prop spinners. These modifications increased top speed to 520 kph (323 mph) but the revisions continued. Kawasaki narrowed the fuselage, increased the wing span and area, revised the nacelles again, and modified the armament package. The new aircraft did not fly until May-June 1941 but performance at last met army standards and they ordered the Toryu into production.

Kawasaki delivered the first Ki-45 Kai (modified) in August 1942 but Toryus did not reach combat units in China until October. Unlike many Japanese Navy fighter airplanes, the Ki-45 aircraft had crew armour and fire-resistant fuel tanks. These airplanes also carried a heavy gun battery that usually consisted of 20 mm and 37 mm cannons. Toryus operated in the New Guinea area against Allied shipping and attacked Consolidated B-24 Liberator bombers of the 5th Air Force. The Japanese also employed some Ki-45s as night fighters. Field personnel modified these Toryus by substituting the upper fuselage fuel tank for two 12.7 mm machine guns mounted to fire obliquely upwards at a target’s vulnerable belly. This worked so well that the army told Kawasaki to manufacture a night fighter version of the Toryu-the Ki-45 Kai (Mod. C)-with two 20 mm cannon, mounted obliquely, and a 37 mm cannon mounted in the lower fuselage.

In June 1944, 20th Air Force bomber crews flew Boeing B-29 Superfortresses on the first raids against the Japanese home islands since Doolittle’s attack back in May 1942. Bad weather and attacks by Japanese fighter interceptors, including Ki-45 Toryus, hampered these raids. On one mission, Ki-45 pilots downed eight Superfortresses.

On March 9, 1945, the 20th Air Force began flying low altitude attacks at night using incendiary bombs. These missions marked a radical departure from the traditional American high-altitude, daylight bombing strikes. The Japanese fought back with anti-aircraft gunfire and night fighter attacks. As many as six Sentais (groups) of NICK night fighters defended the home islands by war’s end. The Ki-45 Kai Hai (Mod. C) the Japanese Army’s only night fighter, operated alongside Navy night fighters including the Nakajima J1N1-S Gekko (IRVING) and P1Y1-S Byakko (FRANCIS). Examples of the IRVING and FRANCIS are also preserved in NASM’s collection. The NASM Ki-45 Kai Hai (Mod. C) is the last known survivor of 1,700 Ki-45s built by Kawasaki. The company built a total of 477 Kai Hai C night fighters.

The NASM airplane was produced in the second of three batches and the thrust-augmentation exhausts fitted to the engines to improve speed and reduce glare at night identify aircraft in this batch. This NICK was one of about 145 Japanese airplanes returned to the United States for evaluation after the war. The Navy shipped them to Norfolk, Virginia, aboard the escort carrier USS Barnes. On December 8, 1945, the Navy transferred the NICK to the U. S. Army Air Forces at Langley Field, Virginia. Personnel at Langley shipped the Ki-45 to the Air Depot at Middletown, Pennsylvania, for overhaul and flight test. During the next few months, the aircraft was extensively test-flown at Wright Field, Ohio, and Naval Air Station Anacostia in the District of Columbia. During the army’s evaluation, pilots reported that NICK handled very poorly on the ground. They also did not like the cramped cockpit, excessive vibration, and the poor visibility. Takeoff distance, climb speed, flight characteristics, approach and landing, and manoeuvrability were all rated as good to excellent.

The first Ki 45s were deployed in Southeast Asia and, despite exceptional maneuverability for their size, were at a disadvantage fighting single-engine opponents. Given their speed and heavy armament, however, they proved ideal for ground attacks and antishipping strikes. Moreover, the Ki 45 was also an effective bomber interceptor and played havoc with American B-24 formations throughout Burma and Indochina. When the B-24s switched to night attacks, the Ki 45 was converted into a night fighter by mounting heavy cannons on top of the fuselage in slanted fashion. Considerable success was achieved, which gave rise to the Ki 45 KAIc, a dedicated night-fighter version, in 1944. These machines also performed useful work against high-flying B-29s over Japan toward the end of the war. More ominously, on May 27, 1944, it fell upon four Nicks to perform the first army kamikaze attacks against American warships off Biak.



    Prototype aircraft

KI-45 Type 1

    Modified operative models

Ki-45 KAI

    Prototype aircraft

Ki-45 KAI

    Pre-series aircraft

Ki-45 KAIa

    Toryu: Two-seat fighter Type 2 of Army (Mark A) initial model of series, one 20mm Ho-3 in ventral position, two Ho-103 12.7mm in the nose and a flexible 7.92mm in the back position

Ki-45 KAIb

    retrofit version based on the KAIa, 20mm belly cannon replaced by a 37mm type 94 tank gun

Ki-45 KAIc

    Mark C version against naval objectives, one 37 mm (1.46 in) Ho-203 automatic cannon in the nose, one 7.92 mm (.312 in) machine gun in the back position.

Ki-45 KAId

    Mark D, a modified Model B, night fighter version, equipped with one 37 mm (1.46 in) Ho-203 cannon in nose and two fixed 20 mm Ho-5 cannons in a Schräge Musik-style dorsal frontal position, and one 7.92 mm (.312 in) Type 98 machine gun in back position.

Ki-45 II

    Single-seat fighter prototype; later re-designated Ki-96.

Total production: 1,691 or 1701 units depending on source.

Specifications (Ki-45 KAIc)

General characteristics

    Crew: 2

    Length: 11 m (36 ft 1 in)

    Wingspan: 15.02 m (49 ft 3 in)

    Height: 3.7 m (12 ft 2 in)

    Wing area: 32 m2 (340 sq ft)

    Airfoil: root: NACA 24015; tip: NACA 23010

    Empty weight: 4,000 kg (8,818 lb)

    Gross weight: 8,820 kg (19,445 lb)

    Powerplant: 2 × Mitsubishi Ha-102 14-cylinder air-cooled radial piston engines, 783 kW (1,050 hp) each

    Propellers: 3-bladed constant-speed propellers


    Maximum speed: 540 km/h (340 mph, 290 kn)

    Range: 2,000 km (1,200 mi, 1,100 nmi)

    Service ceiling: 10,000 m (33,000 ft)

    Rate of climb: 11.7 m/s (2,300 ft/min)

    Wing loading: 171.9 kg/m2 (35.2 lb/sq ft)

    Power/mass: 0.26 kW/kg (0.16 hp/lb)


1 × 37 mm (1.457 in) Ho-203 cannon, 1 × 20 mm (0.787 in) Ho-3 cannon, 1 × 7.92 mm (0.312 in) Type 89 machine gun on a flexible mount in the rear cockpit

Japanese Fortifications and strongholds I

Fortunately for the economic survival of Japan, in subsequent decades defensive strategies, particularly in large-scale campaigns, began to center on entrenchments and fortifications, rather than on evasion and refusal of battle. Whether bushi perceived a problem and responded directly to it, or simply stumbled onto a solution for other reasons, is difficult to assess. Whatever their genesis, however, in the event, the new tactics helped prevent recurrences of devastation on the level of the Tadatsune episode.

The first significant campaign in which fortifications played a major role appears to have been Minamoto Yoriyoshi’s so-called Former Nine Years’ War against Abe Yoritoki and his sons, waged from 1055 to 1062. This contest took place in Mutsu, in the northeast, a region where warriors were heir to a three century-old tradition of establishing stockades as bases from which to control the local population. The Abe’s strategy throughout the conflict centered on ensconcing themselves and their followers behind bulwarks and palisades, in an effort to outlast Yoriyoshi’s patience and resolve. Such tactics played on the eagerness of Yoriyoshi’s troops to get back as soon as possible to their own lands and affairs. As Yoriyoshi’s lieutenant Kiyowara Takenori warned him:

Our government army is made up of mercenaries, and they are short of food. They want a decisive fight. If the rebels were to defend their strongholds and refuse to come out, these exhausted mercenaries could never maintain an offensive for long. Some would desert; others might attack us. I have always feared this.

If the Mutsuwaki, a nearly-contemporaneous literary account of the war, is to be believed, the forts the Abe manned, and the defenses they employed, could be elaborate:

On the north and east sides of the stockade there was a great swamp; the other two sides were protected by a river, the banks of which were more than three jo [about 10 meters] high and as unscalable as a wall. It was on such a site that the stockade had been built. Above the stockade the defenders stood towers, manned by fierce warriors. Between the stockade and the river, they dug a trench. At the bottom of the trench they placed upturned knives and above the ground they strew caltrops. Attackers at a distance they shot down with oyumi; at those who drew close they hurled stones. When, intermittently, an attacker reached the base of the stockade wall, they scalded him with boiling water and then brandished sharp swords and killed him. Warriors in the towers jeered the besieging army as it approached, calling for it to come forth and fight. Dozens of servant women climbed the towers to taunt the attackers with songs. . . .

Yoriyoshi’s tactics against this stockade were equally elaborate – and ruthless as well:

The attack began on at the hour of the hare [5:00-7:00 am] on the following day. The assembled oyumi shot throughout the day and night, the arrows and stones falling like rain. But the stockade was defended tenaciously and the besieging army sacrificed hundreds of men without taking it. The following day at the hour of the sheep [1:00-3:00 pm] the besieging commander ordered his troops to enter the nearby village, demolish the houses, and heap the wood in the dry moat around the stockade. He further told them to cut thatch and reeds and pile these along the river banks. Accordingly much was demolished and carried, cut and piled, until at length the stacks towered high as a mountain. . . . The commander then took up a torch himself and threw it on the pyre. . . . A fierce wind suddenly sprang up and the smoke and flames seemed to leap at the stockade. The arrows previously fired by the besieging army blanketed the outer walls and towers of the stockade like the hairs of a raincoat. Now the flames, borne by the wind, leaped to the feathers of these arrows and the towers and buildings of the stockade caught fire at once. In the fortress thousands of men and women wept and cried out as with one voice. The defenders became frantic; some hurling themselves into the blue abyss, others losing their heads to naked blades.

The besieging forces crossed the river and attacked. At this time several hundred defenders put on their armor and brandished their swords in an attempt to break through the encirclement. Since they were certain of death and had no thought of living, they inflicted many casualties upon the besieging troops, until [the deputy commander of the besieging army] ordered his men to open the cordon to let the defenders escape. When the warriors opened the encirclement, the defenders immediately broke for the outside; they did not fight, but ran. The besiegers then attacked their flanks and killed them all. . . . In the stockade dozens of beautiful women all dressed in silk and damask, minutely adorned in green and gold, wept miserably amidst the smoke. Every one of them was dragged out and given to the warriors, who raped them.

Yoriyoshi’s experiences with the Abe may have become the inspiration for increasingly widespread use of fortifications elsewhere in the country; nevertheless defensive works as elaborate or permanent as those Yoritoki and his sons occupied remained rare outside the northeast until the fourteenth century. Most Heian- and Kamakura-period fortresses were comparatively simple structures erected for a single battle or campaign.

Unlike the castle homes – protected by deep moats, wooden palisades and earthworks – of Sengoku-era warlords, early medieval bushi residences were scarcely distinguishable from those of other rural elites, and differed only in size and opulence from the dwellings of nobles in the capital.

Heian, Kamakura and Nambokucho warriors built their homes on level ground, usually on relatively high points in or very near the alluvial lowlands of rivers, and immediately adjacent to paddies and other agricultural fields. The main houses, stables and other key buildings were surrounded by water-filled ditches and hedges or fences, and accessed through wooden- or thatch-roofed gates. None of these features, however, appear to have been designed for military expediency.

Ditches were narrow and shallow – less than a meter wide and 30 cm deep  – and enclosed areas of 150 by 150 meters or more, presenting an impractically long line to defend with the small number of men normally available to early medieval landowners. They seem, therefore, to have served primarily as components of irrigation works, used to warm water and as a safeguard against droughts. Similarly, fences depicted in medieval artwork are low – a meter or so in height – and constructed of wood, thatch or natural vegetation, making them more suitable for controlling wandering animals than for keeping out marauding warriors. Careful archeological studies indicate that deeper moats and earthworks did not appear around warrior homes until the fourteenth century, and did not become widespread until the fifteenth.

The terms “shiro” or “jokaku” (usually translated as “castle” in later medieval contexts) appear frequently in diaries, chronicles, documents and literary accounts of late twelfth- and thirteenth-century warfare, but only in wartime situations, and nearly always in reference to field fortifications, erected for a particular battle. Such breastworks were intended to be temporary, and were rudimentary in comparison to the castles of the later medieval period, but they were not always small in scale. Some, like the famous Taira defense works erected in 1184 at Ichinotani, near Naniwa on the Harima border of Settsu province, could be quite impressive:

The entrance to Ichinotani was narrow; the interior was broad. To the south was the sea; to the north were mountains – high cliffs like a folding screen. There seemed not even a small space through which horses or men could pass. It was truly a monumental fortress. Red banners in unknown numbers unfurled, blowing toward heaven in the spring wind like leaping flames. . . . The enemy would surely lose its spirit when it looked upon this.

From the mountain cliffs to the shallows of the sea they had piled up large boulders, and over these stacked thick logs, on top of which they positioned two rows of shields and erected double turrets, with narrow openings through which to shoot. Warriors stood with bows strung and arrows at the ready. Below this, they covered the tops of the boulders with brush fences. Vassals and their underlings waited, grasping bearclaw rakes and long-handled sickles, ready to charge forth when given the word. Behind the walls stood countless saddled horses in twenty or thirty rows. . . . In the shallows of the sea to the south were large boats ready to be put to oars instantly and head to the deeper water, where tens of thousands of ships floated, like wild geese scattered across the sky. On the high ground they readied rocks and logs to roll down upon attackers. On the low ground they dug trenches and planted sharp stakes.

These descriptions, drawn from later literary accounts of the Gempei War, doubtless incorporate considerable exaggeration, but they nevertheless offer important clues about the nature of late twelfth-century fortifications. Two points, in particular, merit special attention. First, the preparations for battle involved provisions for escape – “countless saddled horses in twenty or thirty rows” and “large boats ready to be put to oars instantly,” to ferry troops to “tens of thousands of ships” waiting in deeper water – in addition to the defensive works. And second, as formidable as Ichinotani was, it was neither a complete enclosure nor fortified in all directions. In fact, the Taira defeat there was brought about, in part, by Minamoto Yoshitsune’s attack from the hills behind it. Similar tactics decided other key battles of the age as well.

Late Heian and early Kamakura “jokaku” were defensive lines, not castles or forts intended to provide long-term safe haven for armies ensconced within. Many were simply barricades erected across important roads or mountain passes. Others were transient wartime modifications to temples, shrines or warrior residences. Their purpose, in either case, was to concentrate campaigns and battles: to slow enemy advances, thwart raiding tactics, control selection of the battleground, restrict cavalry maneuver, and enhance the ability of foot soldiers (who could be recruited in much larger numbers) to compete with skilled horsemen. And they were expendable, as well as expedient; they were never the sites of sustained sieges or – by choice – of heroic final stands. Contingency planning normally provided for withdrawal and reestablishment of new defensive lines elsewhere.

Picture scrolls indicate that most of the defense features cataloged in the descriptions of Ichinotani were commonly deployed by the late thirteenth century, and most appear in descriptions of other Gempei War-era fortifications in Heike monogatari and its sister texts. Curiously, however, some of the simplest devices – brush barricades (sakamogi) and shield walls (kaidate) – cannot be corroborated in more reliable sources for the 1180s.

Shield walls were exactly what the name implies: rows of standing shields erected behind or on top of other defense works. Standing shields had been used as portable field fortifications since the ritsuryo era, and were also deployed as counter-fortifications by besieging armies. Kaidate were used on boats as well, to convert what were otherwise fishing vessels to warships.

Sakamogi (literally, “stacked wood”) appear to have been essentially piles or hedges of thorny branches placed in front of the principal defensive palisade. They served as an application of what is sometimes called “the principle of the curtain”: a light barrier designed to break the momentum of an enemy charge, dissipating its shock power and holding the enemy under fire before he can bring force against the main walls. Brush fences of this sort were architecturally simple, yet extremely effective for the task: Martin Brice notes that, during World War I, thorn enclosures, called boma or zareba, built by the Masai of Tanzania and Kenya proved as difficult to cross, and as resistant to high explosive bombardment, as barbed wire!

Masai thorn fences represented a wartime application of a device normally used to contain and protect livestock. Japanese sakamogi may have had similar origins. Such a military adaptation of a technology developed for animal control was entirely apropos for early medieval warriors, whose main concern was restricting the movement of enemy horsemen. Brush curtains are, however, vulnerable to fire, which, as we have seen, was a favorite weapon of early bushi.

Japanese Fortifications and strongholds II

Ditches and moats, another tool borrowed from horse and cattle breeders, offered twelfth-century military architects a more durable curtaining wall for their field fortifications. Because they were intended to halt or hinder the advance of mounted troops, rather than keep hordes of attacking infantry at bay, such ditches needed to be only a few meters wide or deep, and were usually dry. Many were topped on the inner side with earthen ramparts constructed from the dirt removed to dig the trench.

Among the most remarkable examples of early medieval military ditches is the massive defensive line Fujiwara Yasuhira prepared when he learned of Yoritomo’s invasion plans in 1189. This barrier, the remains of which can still be seen today, effectively blocked the whole of the Tosando, the only route into Mutsu. Stretching some 3 kilometers between Azukashiyama and Kunimishuku, on the northeast end of the Fukushima plain, it was about 15 meters wide and 3 meters deep, featuring steep ramparts of packed earth, augmented here and there with stone. Yasuhira also set up a secondary line some 20 kilometers behind this, and stretched ropes across the Natori and Hirose rivers to form a tertiary line 30 kilometers behind that.

The line of walls constructed along the coastline of northern Kyushu, as a defense against the Mongol invasions of the late thirteenth century, was even grander. Composed of earth, granite and sandstone, and standing 2 to 3 meters high and equally wide, it stretched nearly 10 kilometers.

Fortifications of this scale required enormous labor resources. Manpower costs for Yasuhira’s Azukashiyama ditch have, for example, been calculated at more than 20,000 working days. Thus, even mobilizing the entire adult peasant population of the neighboring three districts – at the time, about 5,000 men – the project would have taken forty days or more to complete. Workers for military construction projects were usually conscripted locally, on the basis of various tax obligations.

Ditches and dry moats, augmented with sakamogi or earthen ramparts, were more than adequate barriers against Japanese ponies. Unlike European or later medieval Japanese castles, moreover, twelfth-century jokaku did not trap the defenders inside, and therefore constituted only a part of the strategy underlying the battles and campaigns in which they were deployed. Indeed, the construction and use of barricades was intimately bound up with the question of how and when to throw one’s own mounted troops at the enemy. Warriors waited behind the walls for the right moment to charge out and counter-attack, or to withdraw to secondary or tertiary lines.

Wooden gates (kido or kidoguchi), through which defenders on horseback could rush forth to assault besieging forces, constitute the one ubiquitous feature of late twelfth- and early thirteenth-century fortifications. As the only points at which mounted warriors – of either side – could readily cross the barricades, they were usually the nodal points of battle. Consequently, they were the most heavily defended parts of the line, flanked by one or more shielded platforms (yagura, literally, “arrow stores”) from which archers could shoot down at approaching troops.

On occasion, attacking armies mobilized laborers to build counterfortifications or dismantle enemy barricades. In the Mutsu campaign, for example, Yoritomo set eighty men, under Hatakeyama Shigetada, to hauling rocks and earth with plows and hoes in order to fill in parts of the Azukashiyama ditch, so that his horsemen could cross. But while the sheer size of the Azukashiyama ditch, and of Yoritomo’s army, made counter-mining operations practical and necessary, against less extensive – and more densely defended – fortifications this tactic would have exposed the workers and their supervisors to rocks and arrows launched from the ramparts. Similarly, bushi who dismounted to scale the walls of the trench made themselves vulnerable to horse-borne counter-offenses, or made it easier for the defenders to withdraw and escape. More commonly, therefore, warriors confronting fortifications focused on storming the entrances and on flanking attacks.

The architectural features, and the tactical considerations, that governed Kamakura-period fortifications continued to dominate the fortresses and skirmishes of the Nambokucho era as well. But the battles of the 1330s also introduced a new role for warrior strongholds, new kinds of fortresses, and new forms of siege warfare.

During the eighth month of 1331, Go-Daigo fled the capital and “reestablished his imperial abode” in Kasagi temple, on the border between Yamato and Yamashiro. There he speedily erected fortifications and began sending out calls to arms. In response, the shogunate dispatched Sasaki Tokinobu, in command of troops from Omi and reinforced by 800 horsemen under the Kuge and Nakazawa families of Tamba, to capture him. On the first day of the ninth month, as 300 outriders from this force, under Takahashi Matashiro, approached the foot of Mount Kasagi, they were ambushed and routed by the castle garrison. Concerned that “should rumors spread of how [the shogunate’s men] lost this first battle, and how the castle was victorious, warriors of the various provinces would gallop to assemble there,” Kamakura promptly sent a massive army – nearly 75,000 men, according to Taiheiki – to invest the castle.

At dawn, on the third day of the ninth month, this force assaulted Kasagi “from all directions.” But the castle defenders fought back fiercely, showering the attacking troops with rocks and arrows such that:

Men and horses tumbled down one upon another from the eastern and western slopes surrounding the castle, filling the deep valleys and choking the roads with corpses. The Kozu River ran with blood, as if its waters reflected the crimson of autumn leaves. After this, though the besieging forces swarmed like clouds and mist, none dared assail the castle.

While the shogunal leaders stood at bay in front of Kasagi castle, “which held strong, and did not fall even when attacked day and night by great forces from many provinces,” to their rear other imperial loyalists were “raising large numbers of rebels, and messengers rushed to shogunal headquarters daily”:

On the eleventh day of that month, a courier was dispatched from Kawachi, reporting that, “Ever since the one called Kusanoki Hyoe Masashige raised his banner in service of the Emperor, those with ambitions have joined him, while those without ambition have fled to the east and west. Kusanoki has impressed the subjects of his province, and built a fortress on Akasaka mountain above his home, which he has stocked with as many provisions as he could transport, and manned with more than 500 horsemen. Should our response lag, this must become a troublesome matter indeed. We must direct our forces toward him at once!” . . .

Meanwhile, on the thirteenth day of that month a courier was dispatched from Bingo, with the message that, “The lay monk Sakurayama Shiro and his kinsmen have raised imperial banners, and have fortified [Kibitsu] shrine of this province. Since they have ensconced themselves within it, rebels of nearby provinces have been galloping to join them. Their numbers are now more than 700 horsemen. . . . If we do not strike them quickly, before night gives way to day, this will become an immense problem.”

Go-Daigo’s loyalist followers looked to fortifications not just as tactical barricades – devices for focusing battles, delimiting campaigns, or trammeling enemy horsemen – but as rallying points, sanctuaries, and symbols of resistance. Thus, while most twelfth- and thirteenth-century defense works had been constructed across or adjacent to roads, beachheads and other travel arteries, Kusanoki Masashige and his allies ensconced themselves in remote mountain citadels, whose purpose and presence defied Kamakura authority, and served as a beacon to other recruits.

Descriptions in Taiheiki and other texts, and depictions of fortifications in fourteenth-century scroll paintings, indicate that fortresses of the period were architecturally similar to those of the early Kamakura era, albeit now fully enclosed and often reinforced with wooden palisades and additional yagura erected at various points along the walls between, as well as adjacent to, the gates. The latter two innovations were a necessary consequence of the first. For, unlike the easily abandoned defensive lines favored by twelfth- and thirteenth-century warriors, the citadels Kusanoki and his compatriots occupied allowed the defenders no rapid means of escape or retreat. Indeed, they invited encirclement and siege, beckoning enemy horsemen – hitherto stymied by trenches and simple earthworks – to dismount and assault the walls directly.

Compact enough to be easily defended on all exposures, and located on terrain sufficiently treacherous to render them difficult to approach quickly or in large numbers, such citadels were not readily taken by direct onslaught – even if besieging forces did not really have to contend with the collapsing sham walls, decoy armies of mannequins, and other imaginative slight-of-hand tactics Taiheiki attributes to Kusanoki Masashige. More often, it seems, mountain castles fell to attrition – sometimes hastened by cutting off the garrison’s water or food supplies. Others were captured by infiltration or stealth.

In this way, relatively small numbers of warriors could tie up sizeable enemy forces for long periods, buying time and credibility for Go-Daigo’s cause, and whittling away at the morale of Kamakura’s troops. Kusanoki’s garrison of “more than 500 warriors” on Mount Akasaka in 1331 held “what looked to be a hastily-devised” fort “less than one or two hundred meters across” for nearly three weeks, against a shogunal army allegedly comprising “more than 20,000 horsemen.” In 1333, he held Chihaya castle near Mount Kongo in Kawachi for more than two months, while a besieging force “rumored to have been over 800,000 horsemen at the beginning” of the siege dwindled to “scarcely 100,000 riders.”


This is the massive bridge of Takao on 21 December 1939 after her Modernisation. Her upper bridge has been reduced in height and a tripod replaced the quadruped foremast. The new twin 25mm AA mount is shown abreast of the funnel and twin 13mm machine guns have been added to sponsons on either side of the bridge. Notice the 610mm torpedoes swung outboard. To reduce the threat to the ship by accidental explosion of one of their warheads, doctrine called for them to be swung outboard in this fashion before going into battle.

This is Chokai, photographed in 1940. Chokai was originally slated to receive the same modernisation that was given to Takao and Atago in 1940 but the refit was cancelled in order to ready the fleet for war. As a consequence, the upper levels of the bridge retained their initial appearance in large measure. The horizontal yardarm on the foremast is another feature of the unmodernised Chokai and Maya; Atago and Takao after modernisation had yardarms which slanted upwards.

On 1 May 1938 Takao was at Yokosuka awaiting her Modernisation. This photograph shows her appearance on that day with RDF shack mounted inside the quadruped foremast and totally inadequate 7.7mm machine gun abreast of the forward funnel.

On 14 July 1939 Takao ran full power trials after her Modernisation refit. Even with the addition of an upper torpedo blister to improve stability and lessen draft, the wake would still swamp the lower row of scuttles if they were open. Her new tripod foremast and relocation of her mainmast to just forward of No 4 barbette are clearly shown. During these trials Takao hit 34.25 knots at 133,100shp on the measured mile.

Takao 1932
Takao 1944


Since the cruisers of the Takao class were newer than the Myokos, they received very few alterations early in their careers. In August 1933 new HA directors were installed. As a result of the typhoon damage to Myoko in September 1935, the Takao class also received hull strengthening plates from May to September 1936, Takao and Maya also received heavier lattice cranes to the mainmast for aircraft handling, to replace the pole derricks originally fitted. In Maya blast screens for the searchlight towers were removed and new searchlights fitted. Further minor modifications were made in 1937 and 1938. In May–June 1937 Takao received the new searchlights, a shortened foremast and added a radar room inside the quadruped foremast. From October 1936 to July 1937 Chokai received the same treatment, as well as replacement of the Vickers 40mm guns by quadruple Hotchkiss 13.2mm guns and the new lattice crane. Maya received the radar room and AA replacement in December 1937 to January 1938. Other than hull strengthening plates, Atago did not receive these modifications.

By 1937 plans were underway to thoroughly modernise the Takao class, scheduled from 1938 to 1939 for Takao and Atago, with Chokai and Maya to follow in 1940 to 1941. Takao underwent modernisation from May 1938 to August 1939 and Atago from April 1938 to October 1939, but war intervened before Maya or Chokai could be taken in hand. Thereafter ships of the Takao class could be easily identified as to which group they belonged.


The main details are given in the summary table. The four Type 96 twin 25mm guns were positioned on either side of both funnels and the two Type 93 twin 13mm on bridge sponsons (replaced by twin 25mm mounts in the fall of 1941). New gun platforms for the planned twin 127mm (5in) were added but the new guns were not actually installed until March and April 1942 in unshielded mounts. Two four-charge depth charge racks were added to the stern. The upper bridge was rebuilt to reduce topweight and received new range finders. The aircraft deck rails were changed to match the pattern already installed on the Myoko class, along with the heavier catapults. After the refit one Type 94 ‘Alf’ three-seat and two Type 95 ‘Dave’ two-seat floatplanes were carried, but the Type 0 ‘Jake’ replaced the ‘Alf’ in November 1942 and the Type 0 ‘Pete’ replaced the ‘Dave’ in 1942.

The torpedo bulge was enlarged along the same lines as those in the modernised Myoko class, so Takao and Atago had torpedo bulges that were visible above the waterline while Maya and Chokai did not. The new torpedo bulges greatly increased stability: revised design draft was 6.41m but at trial displacement of 14,838 metric tons, the draft was 6.32m. New bilge keels were also fitted.

When it was clear that Maya and Chokai could not receive the same modernisation, a few less extensive changes were made in 1941. The twin torpedo mounts were adapted to receive the newest model of 610mm torpedo. The new heavier catapults were also installed, although they initially received the same complement of floatplanes as Takao and Atago. The quadruple 13mm machine guns on either side of the aft funnel were replaced by Type 96 twin 25mm mounts and twin 13mm machine gun mounts were added on either side of the bridge.

After the Dutch East Indies operations, Maya and Chokai had the twin 13mm guns on the bridge replaced by twin 25mm guns and two additional twin 25mm mounts were placed on either side of the forward stack. They also received the two depth charge racks at the stern, as previously fitted to Takao and Atago. At the end of the Guadalcanal campaign, in February 1943 the Takao class was slated for their First Wartime Modification. Takao and Atago were refitted from July to August 1943 with additional light AA of two triple 25mm mounts on either side of the mainmast, Type 21 radar and bridge wind baffles. Maya and Chokai received two additional twin 25mm mounts on either side of the mainmast, Type 21 radar and wind baffles from August to September 1943.

The Takao class cruisers, less Maya, received their Second Wartime Modification in the same time period as the ships of the Myoko class. Atago from November to December 1943 and Takao from November 1943 to January 1944 received the same treatment, but Chokai, at Truk, only had ten single 25mm guns added. Maya, however, received a unique refit: she was rebuilt as an anti-aircraft cruiser from December 1943 to April 1944 at Yokosuka. No 3 203mm gun turret and the existing AA armament was removed, and replaced by the new battery shown in the table. Her torpedo armament was also brought up to standard and a centreline depth charge rail added. She was equipped to handle two new Model 11 Zuiun floatplanes but only carried two ‘Jakes’. After these changes, standard displacement rose to 13,350 tons and trial to 15,159 tons. It was planned to give Chokai the same conversion as Maya but this plan was shelved.

By the summer of 1944 the four ships of the Takao class presented three distinctly different appearances, with Takao and Atago substantially identical, Maya unique in her AA configuration, and Chokai the only unit retaining her pre-war appearance with single 120mm mounts, twin torpedo tubes and no above-water torpedo bulge. The Third Wartime Modification for the Takao class was conducted in June and July 1944. Takao and Atago continued to be twins with each receiving an additional four triple and twenty-two single 25mm gun mounts. Maya received an additional eighteen single 25mm mounts. Chokai had the fewest changes, with twelve extra single mounts, as she did not have the additional stability conferred by enlarged torpedo bulges. This was the last appearance for the ships of the class, as Atago, Maya and Chokai were sunk during the Battle of Leyte Gulf. Although Takao managed to limp back to Singapore after being torpedoed in the Palawan passage, she was not repaired. She remained an immobile AA platform and survived the war. She was the last of the Japanese heavy cruisers, as she was not scuttled until 26 October 1946, almost four months after Myoko.

Mitsubishi A6M Zero (1939)

Popularly known as the ‘Zero’, the Mitsubishi A6M was the world’s most capable carrier-based fighter at the time of its appearance, out-performing all land-based contemporaries. Latterly outclassed, it remained in service until the end of the war. This A6M2 was on strength with the 2nd Sentai, 1st Koku Kentai and was operating from the carrier Hiryu during the Battle of Midway in June 1942. In the course of the battle, the IJN put up large formations of Zero fighters for protection, but these could not prevent the loss of four Japanese carriers by the U.S. Pacific Fleet.

The brainchild of prolific designer Jiro Horikoshi, the Mitsubishi A6M (Allied reporting name ‘Zeke’) was schemed as a replacement for the same company’s A5M carrier fighter. A cantilever low-wing monoplane, the A6M1 prototype completed its maiden flight in April 1939 and in this form was powered by a Mitsubishi Zuisei 13 radial engine. In production form, the A6M2 of early 1940 introduced a new Nakajima Sakae 12 powerplant and was armed with a pair of wing-mounted 20mm (0.79in) cannon, plus two machine guns in the nose. The new engine was a result of early testing, in which the A6M1 had demonstrated excellent performance with the exception of maximum speed, which had failed to meet the original specification.

The Japanese attack on Rabaul in January 1942 was typical of the whirlwind successes in which the A6M was pitched in the initial phase of the war in the Pacific. Air power on Rabaul, the key strategic base on the island of New Britain, was provided by Australian Hudson light bombers and Wirraway reconnaissance aircraft, but there was no genuine fighter cover. On 20 January, a force of 120 A6M2s, Aichi D3A1s and Nakajima B5Ns took off from the carriers Zuikaku, Shokaku, Kaga and Akagi, attacking installations at Rabaul. Slicing through gallant opposition put up by the Wirraways, the IJN aircraft paved the way for a task force of 5300 men that landed at Simpson Harbour on 23 January, securing the port and the airfield at Kavieng. After capturing Rabaul, Japan established a major base and proceeded to land on mainland New Guinea, advancing towards Port Moresby and Australia.

As early as 1937 the Imperial Japanese Navy began searching for a craft to replace its A5M carrier-based fighters. That year it issued specifications so stringent that only Mitsubishi was willing to hazard a design. Specifically, the navy wanted a fighter of prodigious range and maneuverability, one able to defeat bigger land-based opponents. A design team headed by Jiro Horikoshi originated a prototype in 1939. The A6M was a study in aerodynamic cleanliness despite its bulky radial engine. It had widetrack undercarriage for easy landing and was heavily armed with two cannons and two machine guns. Tests proved it possessed phenomenal climbing and turning ability, so it entered production in 1940, the Japanese year 5700. Henceforth, the new fighter was known officially as the Type 0, but it passed into history as the Reisen, or Zero.

A small production batch of 30 Zeroes was sent to China in the summer of 1940 for evaluation, and they literally swept the sky of Chinese opposition. The official military designation for the new warplane was Navy Type 0 Carrier Fighter and in 1940 initial combat trials were undertaken in China by a preproduction batch. The antiquated Polikarpov fighters flown by the Chinese proved to be no match for the Zero. It was in the course of these operational trials that the Zero recorded its first aerial victory, in September 1940. By the end of that year, the Zero detachment had claimed 59 victories without loss.

Such prowess was duly noted by Claire L. Chennault, future commander of the famed Flying Tigers, but his warnings were ignored. Zeroes subsequently spearheaded the Japanese attack on Pearl Harbor in December 1941, and over the next six months they ran roughshod over all Allied opposition.

Once entering combat in World War II, the highly agile A6M2 proved itself an immediate success, quickly gaining aerial supremacy during the Imperial Japanese Navy’s campaigns in the East Indies and Southeast Asia. The A6M2 was the IJN’s premier fighter during the raid on Pearl Harbor in December 1941, in which eight Zero fighters were lost from a total of 105 involved in the surprise attack on the U.S. Navy fleet. The A6M remained the service’s pre-eminent fighter in theatre as fighting extended to Malaya, the Philippines and Burma. Along the way, it demonstrated its superiority against lesser Allied types in theatre, including the Brewster Buffalo, Curtiss P-36 and P-40 and Hawker Hurricane fighters. Japan’s leading ace of the Pacific war, Saburo Sakai, flew a Zero, who is believed to have achieved 64 aerial kills.

An improved A6M3 entered service in spring 1942, now powered by a Sakae 21 with two-stage supercharger. Not only supremely manoeuvrable, the Zero was also well equipped for fighting at the extended ranges encountered in the Pacific theatre. The aircraft could carry a fuel tank under the fuselage to increase the endurance of its long-range fighter patrols. Even before the arrival of the powerful Hellcat, however, the A6M had begun to suffer at the hands of the Grumman F4F Wildcat, which, although inferior in terms of performance and agility, was better able to withstand battle damage and possessed heavier-hitting armament, self-sealing tanks and armour protection for the pilot. While the Zero was always fast, it was also underpowered, and as a result the design stressed lightweight construction. This, in turn, led to a fighter that was vulnerable to even machine gun fire, and had little in the way of armour protection.

However, following the Japanese defeat at Midway in June 1942, the fabled fighter lost much of its ascendancy to new Allied fighters and a growing shortage of experienced pilots. New and more powerful versions of the Zero were introduced to stem the tide, but relatively weak construction could not withstand mounting Allied firepower. Furthermore, the additional weight of new weapons and equipment eroded its famous powers of maneuver.

Changing Fortunes

The Battle of Midway of June 1942 represented a watershed for the Zero, and thereafter the Japanese fighter began to be increasingly outclassed by U.S. opposition, in particular the U.S. Navy’s Grumman F6F Hellcat, which proved to be faster than the Zero at all altitudes. While the A6M3 version had helped to offset the appearance of the Wildcat, it could do little in the face of the Hellcat.

In an effort to wring additional performance out of the basic airframe, the IJN introduced the A6M5, with Sakae 21 and an improved exhaust system. This version was actually slower than the A6M2, but enjoyed a superior rate of climb and was faster in the dive. It was also built in greater numbers than any of the other Zero models. As the tide of the war turned against the Japanese, the Zero was also used for kamikaze raids, and in one action, five A6M5s sunk the U.S. Navy carrier St Lo and damaged three others in October 1944.

The last models in the Zero line comprised the A6M6 of late 1944, with a water-methanol boosted Sakae 31, and the A6M7 fighter/dive-bomber of mid-1945 with a rack under the fuselage for the carriage of a single 250kg (551lb) bomb. In total, in excess of 10,000 Zero fighters were completed, including a floatplane version built by Nakajima as the A6M2N (Allied reporting name ‘Rufe’). As such, it was the most prolific Japanese fighter of all time.

Although the A6M’s vulnerability to the Hellcat in particular was clear by the time of the Battles of the Philippines and Leyte Gulf in 1944, the lack of an adequate replacement meant the Zero was forced to soldier on in IJN service until the bitter end.

By 1945 most A6Ms had been converted into kamikazes in a futile attempt to halt the Allied surge toward the homeland. A total of 10,964 were constructed.

The legendary A6M (the dreaded Zero) was the first carrier-based fighter in history to outperform land-based equivalents, and it arrived in greater quantities than any other Japanese aircraft. Despite the Zero’s aura of invincibility, better Allied machines gradually rendered it obsolete.

A6M5c Type 0 Model 52

Considered the most effective variant, the Model 52 was developed to face the powerful American Hellcat and Corsair, superior mostly for engine power and armament. The variant was a modest update of the A6M3 Model 22, with non-folding wing tips and thicker wing skinning to permit faster diving speeds, plus an improved exhaust system. The latter used four ejector exhaust stacks, providing an increment of thrust, projecting along each side of the forward fuselage. The new exhaust system required modified “notched” cowl flaps and small rectangular plates which were riveted to the fuselage, just aft of the exhausts. Two smaller exhaust stacks exited via small cowling flaps immediately forward of and just below each of the wing leading edges. The improved roll-rate of the clipped-wing A6M3 was now built in.

Sub-variants included:

* “A6M5a Model 52a «Kou»,” featuring Type 99-II cannon with belt feed of the Mk 4 instead of drum feed Mk 3 (100 rpg), permitting a bigger ammunition supply (125 rpg)

* “A6M5b Model 52b «Otsu»,” with an armor glass windscreen, a fuel tank fire extinguisher and the 7.7 mm (.303 in) Type 97 gun (750 m/s muzzle velocity and 600 m/1,970 ft range) in the left forward fuselage was replaced by a 13.2 mm/.51 in Type 3 Browning-derived gun (790 m/s muzzle velocity and 900 m/2,950 ft range) with 240 rounds. The larger weapon required an enlarged cowling opening, creating a distinctive asymmetric appearance to the top of the cowling.

* “A6M5c Model 52c «Hei»” with more armor plate on the cabin’s windshield (5.5 cm/2.2 in) and behind the pilot’s seat. The wing skinning was further thickened in localised areas to allow for a further increase in dive speed. This version also had a modified armament fit of three 13.2 mm (.51 in) guns (one in the forward fuselage, and one in each wing with a rate of fire of 800 rpm), twin 20 mm Type 99-II guns and an additional fuel tank with a capacity of 367 L (97 US gal), often replaced by a 250 kg bomb.

The A6M5 had a maximum speed of 540 km/h (340 mph) and reached a height of 8,000 m (26,250 ft) in nine minutes, 57 seconds. Other variants were the night fighter A6M5d-S (modified for night combat, armed with one 20 mm Type 99 cannon, inclined back to the pilot’s cockpit) and A6M5-K “Zero-Reisen”(model l22) tandem trainer version, also manufactured by Mitsubishi.

Early War Japanese Air Supremacy – the “Zero”

Takeda clan

Hideo Takeda, battle in the Fuji River.

Battle of Nagashino, a painted screen of the XVII-XVIII centuries.

Battle of Nagashino, (1575)

Battle fought by Nobunaga Oda (1534–1582) and his ally Ieyasu Tokugawa (1543–1616) with Takeda Natsunori, around the strategic fortress of Nagashino. In this encounter, the forces of Tokugawa and Nobunaga Oda were the first to rely primarily on massed firepower in the form of Western armaments, helping to transform samurai warfare while pushing both houses closer to hegemony over Japan.

Ieyasu Tokugawa had actually forged a familial alliance with the Takedas, whose territories bordered his own in central Honshu. He married both a son and daughter into the Takeda household in the 1560s, but in the world of shifting alliances and steady warfare that characterized Japan at the time, the alliance quickly foundered. The Takedas were soon at war with the Tokugawa again.

The death of the elder Takeda (Shingen) in 1573, at the hands of a sniper in battle, placed his son Natsunori at the head of the Takeda house. The rising fortunes of the Tokugawa had made them fierce rivals of the Takedas, and when in 1575 a traitor to Tokugawa offered to hand over the vitally strategic castle of Ozaki to the Takedas, Natsunori Takeda jumped at the opportunity. Ozaki was the capital of Mikawa Province, the heart of Tokugawa territory, and its castle was guarded by Tokugawa’s own son.

Takeda led a force of 15,000 warriors in what was expected to be a near-bloodless seizure of Ozaki Castle. Instead, they discovered en route that the treachery had been discovered by Tokugawa. Rather than face a humiliating retreat, Takeda opted to send his troops instead against the nearby fortress of Nagashino, another strategic castle sitting at the convergence of three rivers and guarding the entrance to Mikawa and Totomi Provinces.

Takeda began his siege of the castle in May 1575 but was still unsuccessful when word came that relief forces led by Tokugawa and Oda were on their way. Takeda opted to stand his ground near Nagashino and engage the approaching allied armies, though his forces were outnumbered more than two to one. At the Battle of Nagashino in June 1575, the alliance’s greater numbers and, more important, overwhelming firepower, including musket volley fire by alternating ranks (the first time that this technique is known to have been employed in warfare), carried the day. Takeda lost almost two-thirds of his men and generals, and the mortally wounded Takeda clan would linger only until 1582, when it was overrun for good.

References and further reading: Parker, Geoffrey. The Military Revolution: Military Innovation and the Rise of the West, 1500–1800. Cambridge, UK: Cambridge University Press, 1988. Sadler,A. L. The Maker of Modern Japan: The Life of Tokugawa Ieyasu. Tokyo: Charles E. Tuttle,1937.


The Takeda were descendants of Emperor Seiwa (858-876) and are a branch of the Minamoto clan (Seiwa Genji), by Minamoto no Yoshimitsu (1056-1127), brother to the Chinjufu-shogun Minamoto no Yoshiie (1039-1106). Minamoto no Yoshikiyo (c.?1075 – c.?1149), son of Yoshimitsu, was the first to take the name of Takeda.

For much of the Sengoku Period the provinces controlled by the Sengoku Daimyo were quite well defined and ruled as a stable economic unit. There is little evidence of civil war within these territories except where the Ikko-ikki sectarians were involved. Warfare tended to be confined to clashes between daimyo, particularly at sensitive areas where two territories met. Thus the border between the Takeda, Uesugi and Hojo lands was frequently contested. Kawanakajima, an area of flatland which was effectively a no man’s land for the Takeda and Uesugi, saw no fewer than five battles across its fields. It was such conflicts, coupled with their geographical remoteness from the capital, that acted as a counterweight to whatever pretensions these daimyo might have had to becoming Shogun. Many possessed the necessary military power, but few were fated to exercise it in this direction.

Shingen Takeda, (1521-1573)

A prominent warlord (daimyo) of Japan’s Sengoku period (“the Age of the Country at War”). Shingen Takeda was born Harunobu Takeda in 1521, the eldest son of Katsuyori Takeda, ruler of Kai Province in north-central Japan. Young Takeda overthrew his father in 1541 and installed himself as the provincial shugo (military governor). He then embarked on the conquest of neighboring Shinano Province, which was secured by 1555. However, this action brought him into direct conflict with Kenshin Uesugi (1530-1578) of Eichigo Province, another young and dynamic military figure. For nearly two decades, the two leaders clashed at the battlefield of Kawanakajima, with especially severe encounters in 1553, 1554, 1556, and 1563.

At length, neither side could gain a decisive advantage over the other, and both turned their territorial ambitions elsewhere. During this period, Takeda shaved his head, became a Buddhist priest, and assumed the more familiar name of Shingen.

At this time, Japan was seething with conflict as major families of samurai battled for control of the country. In 1568, Takeda attacked the Imagawa family and drove it from Surguga Province. However, the ever-shifting balance of power forced him to ally with the Hojo, Asakura, and Asai families to oppose the growing strength of Nobunaga Oda. In 1573, Takeda attacked the combined forces of Oda and his surrogate, Ieyasu Tokugawa, at Mikatagahara, driving them from the field. This defeat had the effect of inducing the weakened shogun, Yoshiaki Ashikaga, to denounce Oda, a feat that ultimately led to the shogunate’s downfall. However, Takeda became distracted by events elsewhere and, by failing to follow up this impressive victory, allowed his enemies to consolidate.

In the spring of 1573, Takeda again advanced against Tokugawa and besieged one of his castles in Noda. Events are not clear, but he died either of disease or a gunshot wound on 13 May 1573. The Takeda clan did not outlive his demise and were eliminated as a military threat by Oda at Nagashino in 1575.

Beyond his military prowess, Takeda was also renowned for his administrative and organizational abilities. He placed Kai Province on a very high order of efficiency and was affectionately regarded by the populace. Takeda was also celebrated for his calligraphy and poetry, military guile, and capacity for great acts of both chivalry and cruelty.

The Armies of the Sengoku Jidai

The armies of the Sengoku Jidai were manifestations of the feudal social structure of Japan, which revolved around kinsmen and vassals. The head of the clan and its army was the daimyō, literally translated as “great name”. He was supported by the kashindan. These were a group of blood relatives and retainers associated by family ties, marriage, filial oaths, and hereditary vassalage. The retainers were given land to govern and were expected to provide military support during times of war. 

A standing army was uncommon but was popularised during the later years of the Sengoku Jidai. For the majority of the period, armies were composed of farmers who needed to stand down during the planting and harvesting seasons. Fighting a campaign during idle periods would offer an opportunity for the peasants to earn extra income from looting and possibly get promoted to samurai.

Typically, when a call to arms was issued, each landowning samurai was required to muster a pre-determined quantity of troops and equipment based on his wealth. Troops from all around the province would then converge at a designated place where they would be reorganised into battalions wielding similar weaponry and start practicing drills. The daimyō determined the chain of command for the campaign.  The prominent retainers would act as bushō (general). A taishō (field marshal, commander-in-chief) would be appointed if the daimyō did not intend to take the role himself.

Each general commanded a division comprised of specialised battalions of cavalry, missile and melee troops mustered from their fiefs. These troops were only loyal to their direct lord and the daimyo, not the taishō or other generals. To reflect this, Japanese commanders who are not assigned as the Commander-in-Chief are classified as Ally-Generals. Their units cannot receive any command effects from other generals except the C-in-C.

The Japanese wielded a variety of weapons, the prominent ones being the katana (sword), yari (spear), naginata (polearm), yumi (bow) and teppō (matchlock).  Contrary to popular depictions, the katana was just a sidearm and the yari was the weapon of choice due to its range and versatility. All classes of soldier, from the lowly ashigaru to the elite samurai, wore armour of lamellar construction.  

Before 1530, mounted samurai would primarily use bows, similar to other East Asian cavalry. The switch to the yari and shock tactics happened around the 1530s, pioneered by the Takeda clan.

The main fighting force was foot samurai, augmented by ashigaru. Due to the rugged terrain, the Japanese utilised loose formations and fighting was done man-to-man, as depicted in martial arts and samurai films. Hence they are classified as Warriors.

In 1543, Portuguese merchants introduced matchlock firearms (teppō) to the Japanese. Teppō ashigaru infantry were deployed, but there weren’t enough firearms available to equip large units. These small units are classified as Light Foot and are primarily used as skirmish troops.

By 1551, as battles grew larger, more and more ashigaru infantry were being mustered, as a result of which the proportion of foot samurai in the army was somewhat reduced. The Battle of Nagashino in 1575 showed the Japanese that massed volley fire from firearms behind field defences could defeat samurai cavalry From then on, teppō ashigaru formations were larger and did not engage in mere skirmishing tactics.

By 1577, samurai cavalry had lost its appeal due to changes in battlefield technology and tactics. And by 1592, ashigaru infantry tactics evolved into fighting in close formation. They would receive better training and form the backbone of the Late Sengoku Era army. Ashigaru infantry, including yumi and teppō armed units, are now classified as Medium Foot. A century of fighting also depleted the numbers of available samurai. Just like their mounted counterparts, foot samurai, who still fought man-to-man, were finding it harder to dominate the battlefield against organized peasant foot troops. The 1590s also introduced some other elements of modern warfare such as light artillery, but these were not used as extensively as on the Asian mainland.

Buddhist monks of various temples also trained for combat. They had to take up arms in order to protect their temples from rival sects. These warrior monks were called sōhei. During the Gempei War (1180-1185), the sōhei eventually became embroiled in secular politics as they joined the lords that supported their temple.  This was repeated during the Sengoku Jidai and the daimyō were able to gain the support of sōhei from their local temples.

The monks’ weapon of choice was the naginata, a long-bladed polearm. They also used bows and matchlocks. Occasionally, they can be seen wearing armour underneath their robes but the majority were unarmoured.

The Ikkō-ikki revolution gave some sōhei a new purpose. Instead of fighting for their temples and patrons, they fought under an ideology of equality and independence from the daimyō. Ikkō-ikki rebel armies were mostly made up of sōhei and supported by armed peasant mobs. Samurai who shared their ideals also joined but did not form separate units. The samurai fought alongside the monks and peasants and provided leadership as well as training.

RAN (1985)


Ran is a Japanese-French war film/period tragedy directed, edited, and co-written by Akira Kurosawa, adapted from Shakespeare’s tragedy, King Lear and the legends surrounding daimyō Mōri Motonari. The film stars Tatsuya Nakadai as Hidetora Ichimonji, an aging Sengoku-era warlord who abdicates for his three sons—with disastrous results.


Akira Kurosawa first conceived of the idea for the film that would become Ran (Japanese for “chaos” or “discord”) in the early 1970s, when he read about Mōri Motonari (1497–1571), a powerful daimyō in the Chūgoku region of Japan who is remembered as one of the greatest warlords of the Sengoku period (mid-16th century). Though a brilliant diplomat and strategist, Motonari is best known for an event that probably never happened: the “lesson of the three arrows,” a parable that Motonari illustrated by giving each of his three sons an arrow to break. He then gave them three arrows bundled together and pointed out that although one may be easily broken, three bundled together are impossible to break. Motonari actually had nine sons (two of whom died in childhood) but most prominent of them were the three sons the parable concerns: Mōri Takamoto (1523–1563), Kikkawa Motoharu (1530–1586), and Kobayakawa Takakage (1533–1597). Formulating a scenario that could generate real drama, Kurosawa imagined trouble among the three brothers rather than unity and reasonableness. As he later told an interviewer, “What might their story be like, I wondered, if the sons had not been so good? It was only after I was well into writing the script about these imaginary unfilial sons of the Mōri clan that the similarities to [Shakespeare’s 1606 tragedy, King] Lear occurred to me. Since the story is set in medieval Japan, the protagonist’s children had to be men; to divide a realm among daughters would have been unthinkable” (Grilli, 2008, p. 126). Kurosawa and two co-writers—Hideo Oguni and Masato Ide—had a draft of a screenplay completed by 1975, but Kurosawa would not be able to arrange financing for an expensive, large-scale epic set in medieval Japan for another seven years. In the meantime, he painted storyboards of every shot in Ran and made Dersu Uzala (1975) and Kagemusha (1980), the latter of which he described as a “dress rehearsal” for Ran. In 1982 Kurosawa finally secured funding for Ran from two sources: Japanese producer Masatoshi Hara (Herald Ace Productions) and French producer Serge Silberman (Greenwich Film Productions). After the box office success of Jean-Jacques Beineix’s Diva (1981), Silberman was able to put up most of the money needed to back Ran, which ended up costing ¥2.4 billion (i.e., $12 million), the most expensive Japanese film produced up to that time. Kurosawa cast Tatsuya Nakadai (who played the dual lead roles in Kagemusha) as Hidetora Ichimonji, an aging Sengoku-era warlord based on Mōri Motonari who decides to abdicate as ruler in favor of his three sons. Prior to production, several hundred elaborate costumes had to be created by hand, an arduous process that took two years to complete. Pre-production also involved extensive location scouting and set construction, for example, a castle destroyed in the middle of the movie had to be specially built on the slopes of Mount Fuji, only to be burned down.


Akira Kurosawa was 75 years old when he directed Ran (June 1984–February 1985) and was nearly blind when the initial photography started. He required assistance in order to frame his shots, and his assistants used hundreds of his storyboard paintings as templates to construct and film scenes. Almost the entire film is done in long shot, with only a handful of close-ups. An enormous undertaking, Ran used some 1,400 extras, 1,400 suits of armor (designed by Kurosawa himself), and 200 horses, some of them imported from the United States. Over his long career, Kurosawa worked with the same crew of technicians and assistants. Toward the end of the shoot, Kurosawa lost two of his old stalwarts. In January 1985, Fumio Yamoguchi, the sound recordist on nearly all of Kurosawa’s films since 1949, and Ryu Kuze, action coordinator on many of them, died within a few days of each other. A month later (1 February 1985), Kurosawa’s wife of 39 years, Yôko Yaguchi, also died. Kurosawa halted filming for just one day to mourn before resuming work on the picture.

Plot Summary

[Act I] Hidetora Ichimonji (Tatsuya Nakadai), a powerful warlord near the end of his life, decides to divide his kingdom among his three sons: Taro (Akira Terao), Jiro (Jinpachi Nezu), and Saburo (Daisuke Ryu). The oldest son, Taro, is bequeathed the sought-after First Castle and is named commander of the Ichimonji clan. Jiro and Saburo are given the Second and Third Castles, respectively. Hidetora retains his title of Great Lord, and the two younger sons are expected to rally behind Taro. Saburo calls his father a fool, stating that he can’t expect loyalty from sons who grew up watching their father use the most cruel, heartless methods for power and domination. Hidetora is threatened by his son, but his servant, Tango (Masayuki Yui), defends Saburo. Hidetora responds by exiling both men. Nobuhiro Fujimaki (Hitoshi Ueki), a visiting warlord, sees Saburo’s fervor and forthrightness and asks him to wed his daughter. [Act II] After Hidetora divides his remaining lands between Jiro and Saburo, Taro’s wife, Lady Kaede (Mieko Harada), encourages Taro to gain control of the entire clan. Emboldened, Taro tells Hidetora to give up his title of Great Lord. Hidetora, now betrayed by two sons, runs to Jiro’s castle only to discover that Jiro plans to use him in his own scheme for power and influence. Unsure of where to go, Hidetora and his company depart from Jiro’s castle. Tango finds his father and informs Hidetora of Taro’s new decree: anyone who assists Hidetora will be sentenced to death. Hidetora flees to Saburo’s castle, which was left empty when Saburo went into exile. [Act III] Hidetora and his samurais are attacked by Taro’s and Jiro’s forces. In the ensuing battle, almost all of Hidetora’s men are killed and the Third Castle is set on fire. Hidetora, alone and losing his mind, leaves the castle as it is consumed by flames. During the siege on the castle, Taro is killed by a bullet from Jiro’s general, Shuri Kurogane’s (Hisashi Igawa) gun. Meanwhile, Hidetora wanders the wilderness and is found by Tango, who tries to assist him. The pair take shelter in a peasant’s home, but realize that the peasant is Tsurumaru (Mansai Nomura), the brother of Lady Sué (Yoshiko Miyazaki), Jiro’s wife. Tsurumaru was a victim of Hidetora’s regime: he was blinded and left for dead after Hidetora murdered his father and conquered their land. [Act IV] After Taro’s death, Jiro takes on the title of the Great Lord, moving into the First Castle and commanding the Ichimonji clan. Jiro returns to the castle to find Lady Kaede, unbothered by Taro’s death, waiting to blackmail Jiro into an affair. Lady Kaede uses her influence with Jiro to call for Lady Sué’s death. Jiro orders Kurogane to carry out the task, but he declines, stating that Kaede will be the ruin of both Jiro and the clan. Kurogane runs to tell Sué and Tsurumaru to leave. Meanwhile, two ronin are captured by Tango, who coerces them to reveal plans for assassinating Hidetora. Tango leaves to share the news with Saburo. Hidetora is overtaken by madness and runs off into a volcanic plain while Kyoami (Pîtâ) runs after him. Saburo and Jiro meet on the battlefield and agree on a truce, and Saburo becomes concerned by the report of his father’s onset of madness. While Saburo meets with Kyoami and takes 10 warriors along to rescue Hidetora, Jiro takes advantage of the situation and sends gunners to ambush his brother and father. Jiro also attacks Saburo’s army, which falls back into the woods as the soldiers go on the defensive. As the family is warring, a messenger shares news that Ayabe, a rival lord, is headed towards the First Castle. At the same time, Saburo locates Hidetora, and the father experiences a reprieve from his insanity and begins to heal his relationship with his son. However, in the midst of the reconciliation, one of Jiro’s snipers kills Saburo. Hidetora dies out of sadness. Fujimaki arrives with his troops to see Tango and Kyoami grieving. [Act V] In the meantime, Tsurumaru and Sué get to the ruined castle, but realize that they forgot a flute at Tsurumaru’s home, one that Sué had gifted to Tsurumaru at the time of his banishment. She goes back for the flute, but is discovered and murdered by one of Jiro’s assassins. Simultaneously, Ayabe’s army attacks the First Castle. When Kurogane hears that Lady Sué has been killed by Jiro’s assassin, he corners Kaede and pushes her for information. She comes clean about her plot to obliterate Hidetora and his clan to avenge the deaths of her family members. Kurogane decapitates Kaede for her treachery. As Ayabe’s army overtakes the First Castle, Jiro, Kurogane, and all of Jiro’s men are killed. Tsurumaru is left amidst the rubble, alone.


Ran had its world premiere in Tokyo on 25 May 1985. It was subsequently screened at a number of film festivals before going into staggered general release in about two dozen countries. Ran did not do very well at the box office, initially making only enough to break even. It did, however, receive Oscar nominations for Best Director, Best Art Direction, Best Cinematography, and Best Costume Design (which it won), among many other international nominations and awards. Reviews were, for the most part, adulatory. Vincent Canby wrote, “Though big in physical scope and of a beauty that suggests a kind of drunken, barbaric lyricism, Ran has the terrible logic and clarity of a morality tale seen in tight close-up, of a myth that, while being utterly specific and particular in its time and place, remains ageless, infinitely adaptable … Here is a film by a man whose art now stands outside time and fashion” (Canby, 1985). Roger Ebert called the film “visually magnificent” and said he realized on seeing it again in 2000 that “the action doesn’t center on the old man, but has a fearful energy of its own, through which he wanders. Kurosawa has not told the story of a great man whose sin of pride drives him mad, but the story of a man who has waged war all his life, hopes to impose peace in his old age and unleashes even greater turmoil” (Ebert, 2000). Decades after its release, most film critics and scholars view Ran as Akira Kurosawa’s masterpiece.

Reel History Versus Real History

The story that Ran tells is, of course, entirely fictional. One can only judge its historical accuracy in terms of its depictions of medieval Japanese castles; the look, dress, and demeanor of the Ichimonji clan; the conduct in battle of the samurai; etc. On these counts, Ran has extraordinary verisimilitude.

Kawasaki Ki-61 Hien (Swallow)

With its liquid-cooled engine, long tapered nose and wings of high aspect ratio, the Ki-61 was unique among Nipponese fighter aircraft of World War II and it marked the first attempt by the JAAF to incorporate in a fighter design the armour protection and self-sealing fuel tank which had been shown to be indispensable by early war reports received from Europe. The Hien (Swallow) was so un-Japanese in its appearance that it was initially reported as being a licence-built version of either the Messerschmitt Bf 109 or of an unspecified Italian aircraft, the latter report earning for it the Allied code-name ‘Tony’.

During the twenties and thirties, initially under the guidance of Dr Richard Vogt, the German engineer who later became the chief designer of Blohm und Voss, Kawasaki Kokuki KK were the leading exponents in Japan of liquid-cooled engines and held manufacturing rights for the German BMW VI, a V-12 engine, which powered most of their aircraft during the period. Following the Army’s selection of the Nakajima Ki-27 over their own Ki-28, Kawasaki decided to negotiate with Daimler-Benz for a licence for the new series of twelve-cylinder inverted-vee engines which the German company had developed. Negotiations were successfully concluded in April 1940 when a Japanese technical team brought back from Stuttgart the blueprints for the DB 601A as well as a number assembled engines to serve as production patterns. Adaptation to Japanese production techniques began immediately at Kawasaki’s Akashi plant and the first Japanese-built DB 601A, designated Ha-40, was completed in July 1941. Four months later the Ha-40 had successfully passed all ground tests and production started under the designation Army Type 2 (Kawasaki Ha-40) liquid-cooled engine, rated at 1,175 hp for take-off and 1,100 hp at 4,200 m (13,780 ft).

While negotiating with Daimler-Benz, Kawasaki had approached the Army with initial design studies for various fighter aircraft making use of this engine. As reports from the air war in Europe were showing the apparent superiority of aircraft powered by liquid-cooled engines, the Koku Hombu instructed Kawasaki to proceed with two aircraft of this type: the Ki-60, a heavy interceptor fighter, and the Ki-61, a lighter all-purpose fighter, priority being given to the heavier aircraft. In December 1940, however, the emphasis shifted to the Ki-61 for which Takeo Doi and Shin Owada were responsible. The Ki-61 was a low-wing monoplane of all-metal construction with a wide-track inward-retracting main undercarriage and a retractable tailwheel. It was characterised by a large ventral radiator bath under the fuselage just beneath the wing leading edge. The pilot sat in an enclosed cockpit with a backward-sliding canopy. The aircraft, powered by a Kawasaki Ha-40, showed in its design the strong influence left by Dr Vogt on his Japanese pupils. To provide good manoeuvrability and to obtain long endurance a wing of high aspect-ratio and large area was selected by Takeo Doi, considerable attention being given to weight and drag reduction. An armament of two 12.7 mm (0.5 in) Type 1 (Ho-103) machine-guns mounted in the upper fuselage decking and either two 7.7 mm (0.303 in) Type 89 or two 12.7 mm (0.5 in) Type 1 (Ho-103) wing-mounted machine-guns was selected, this armament representing a one hundred per cent increase over that carried by the Ki-43-I then just entering service.

One year after receiving authorisation from the Koku Hombu to proceed with the design, the first aircraft was completed at the Kagamigahara plant where flight tests began in December 1941. Prior to this event, Kawasaki had been authorised to prepare for production and to purchase the necessary tooling and material. Fortunately the wisdom of this decision was vindicated when the prototype met the most sanguine hopes of its designers and the Army staff. Eleven additional prototypes and pre-production machines were built in the early part of 1942, and following handling and performance tests during which a maximum speed of 591 km/h (367 mph) at 6,000 m (19,685 ft) was reached, Service trials began. The wing loading of 146 kg/sq m (29.9 lb/sq ft), high by Japanese standards of the time, was criticized by military pilots, but the majority of those who flew the aircraft were impressed by its high diving speed, and its armour protection, self-sealing fuel tanks and armament were also commented upon favourably.

The thirteenth Ki-61, the first machine to be built with production tooling, was completed in August 1942 and differed from the prototypes only in minor equipment details, the deletion of a small window on each side of the fuselage ahead of the windshield providing the only recognition feature. During competitive trials against prototypes of the Nakajima Ki-43-II and the Ki-44-I, an imported Messerschmitt Bf 109E and a captured Curtiss P-40E, the Ki-61 was judged to have the best overall performance and to be an effective weapon against enemy aircraft.

Consequently, late in 1942, the fighter was accepted for Service use under the designation Army Type 3 Fighter Model 1A when armed with two fuselage-mounted 12.7 mm (0.5 in) Type 1 machine-guns and two wing-mounted 7.7 mm (0.303 in) Type 89 machine-guns and Model 1B when the wing guns were the 12.7 mm (0.5 in) Type 1. Initial deliveries of the aircraft were made in February 1943 to the 23rd Dokuritsu Dai Shijugo Chutai at Ota, which acted as a pilot conversion and training unit. Combat operations began two months later when the 68th and 78th Sentais were deployed to Wewak on the north coast of New Guinea. Immediately these units proved that the Ki-61s, then named Hien, were better suited to combat the US and Australian aircraft than the Ki-43s, which they supplemented in this theatre, due to their heavier armament, good protection and high diving speed – a performance required to overcome the enemy fighters which favoured hit and run attacks from higher altitude against the nimbler Nipponese fighter aircraft. The idiosyncrasies of the liquid-cooled Ha-40 which powered the Hien caused the aircraft to be difficult to handle on the ground because of the prevailing hot and damp weather but in the air the Ki-61-I was an outstanding aircraft liked by its pilots and respected by its foes.

At an early stage in the design of the Ki-61 replacement of the fuselage-mounted machine-guns by a pair of 20 mm (0.79 in) cannon had been contemplated. However, as cannon of domestic design were not yet available, 388 Ki-61-Ias and -Ibs were modified on the assembly line to carry one 20 mm (0.79 in) Mauser MG151 in each wing. As space in the wing was limited, the cannon had to be mounted on its side, a small underwing fairing covering the breech, while some local strengthening was required because of the increased recoil force. One other aircraft was modified to test the surface evaporation cooling system which Takeo Doi proposed to use on the Ki-64. This experimental Hien had its large ventral radiator replaced by a smaller retractable unit, for use on the ground, mounted further forward, while in flight cooling was provided by steam evaporation through wing condensers with a total area of 14 sq m (150.694 sq ft). Tests began in October 1942 and thirty-five flights – during which a maximum speed of 630 km/h (391 mph) was attained – were made until the end of 1943 when the purpose of the tests was sufficiently achieved.

Operations in New Guinea, New Ireland and New Britain had shown that ease of maintenance had to be improved and Takeo Doi decided to simplify the Hien’s structure in the next version of the aircraft. With the availability of the indigenous 20 mm (0.79 in) Ho-5 cannon the Ki-61-I-KAIc was produced with a pair of these replacing the two fuselage-mounted 12.7 mm (0.5 in) Type 1 machine-guns. Stronger wings, allowing an increase in diving speed and featuring provision for fixed pylons for external stores outboard of the wheel wells, were mated to a slightly longer fuselage with detachable rear section. On this version the retractable tailwheel was replaced by a fixed unit while minor control modifications were incorporated. production of the Ki-61-I-KAIc began in January 1944, and the type had completely supplanted the earlier versions on the Kagamigahara assembly line in August of the same year. Following the introduction of this version the Hien’s production, which so far had been somewhat slow, quickly gained tempo and the monthly rate reached a peak of 254 aircraft in July 1944. Including a few Ki-61-I-KAIds, which were armed with a pair of 30 mm (1.18 in) Ho-105 cannon in the wings and two fuselage-mounted 12.7 mm (0.5 in) Type 1 machine-guns, a total of 2,654 Ki-61-Is and Ki-61-I-KAIs – of which the former type accounted for over half of the total – were built until January 1945 when production was terminated. Many of the Ki-61-Is and Ki-61-I-KAIs saw operation in the New Guinea/Rabaul area with the two previously mentioned Sentais, but they were mostly active in the Philippines campaign of 1944-45 (17th, 18th and 19th Sentais) and over Formosa (Taiwan) and Okinawa (19th, 37th, 59th and 105th Sentais, and 23rd Dokuritsu Dai Shijugo Chutai). Finally the type played an important role in the defence of the Japanese homeland where the Hien-equipped 18th, 23rd, 28th and 244th Sentais were assigned to the Tokyo Defence Area, the 59th Sentai to the Western Defence Area and the 55th and 56th Sentais to the Central Defence Area. Over Japan the Hiens were engaged against the B-29s, US Navy carrier aircraft and, later, against Iwo Jima based P-51 Mustangs. Against the high-flying B-29s the Ki-61-I lacked the necessary altitude performance, but the type was not really outclassed until the arrival of the superb Mustang.

Soon after commencing production of the Ha-40 at the Akashi plant, the Kawasaki engineering team began developing a more powerful version of this engine, the Ha-140. Primary emphasis was placed on altitude rating, and Takeo Doi, urged by the Army Staff to develop an advanced version of the Hien, decided to mount the Ha-140 rated at 1,500 hp for take-off and 1,250 hp at 5,700 m (18,700 ft) in a specially redesigned version of the Ki-61. Completed in December 1943, the first prototype Ki-61-II had a wing area increased by 10 per cent to 22 sq m (236.806 sq ft) and a redesigned aft canopy providing improved pilot visibility. However, flight trials were disappointing as the Ha-140 had more than its fair share of teething troubles, the crankshaft proving particularly weak. Even the airframe was not without its problems, and the enlarged wings, which had been designed to enhance the aircraft’s manoeuvrability and performance at high altitude, suffered from several failures. The handling characteristics, too left much to be desired. Consequently, only eight of the eleven Ki-61-IIs built were tested and the ninth airframe was modified as the Ki-61-II-KAI before completion in April 1944. The fuselage length was increased from 8.94 m (29 ft 4 in) to 9.16 m (30 ft 0 5/8 in), the rudder area was enlarged to offset the increased wetted area and the larger wings were replaced by standard Ki-61-I-KAI wings. The airframe problems were thus eradicated and, when the engine performed smoothly, Ki-61-II KAI was an outstanding interceptor with a maximum speed of 610 km/h (379 mph) at 6,000 m (19,685 ft) and a climb rate of 5,000 m (16,405 ft) in six minutes. Still confident that the persistent engine teething troubles would be eradicated, the Ministry of Munitions, acting on behalf of the Army, instructed Kawasaki to proceed with the mass production of the aircraft under the designation Army Type 3 Fighter Model 2.

Starting in September 1944 the Ki-61-II-KAI was built in two versions, the Model 2A with an armament of two fuselage-mounted 20 mm (0.79 in) Ho-5 cannon and two wing-mounted 12.7 mm (0.5 in) Type 1 machine-guns and the Model 2B with an armament of four 20 mm (0.79 in) Ho-5 cannon, two in the fuselage and two in the wings. The Ki-61-II-KAI never supplanted the Ki-61-I-KAI in operational units as its engine was still suffering from chronic weaknesses, and the comparatively few Hiens of this model saw only limited operational service in Japan. When the engine was operating smoothly the Ki-61-II-KAI was an effective interceptor and was the only Japanese fighter able to maintain combat formation at the operating altitude of the B-29s. However, the lack of skilled workers was by then being badly felt and seldom did the Ha-140 give its full rated power. Finally, production of the Army Type 3 Fighter Model 2 was dealt a crippling blow when, on 19 January, 1945, the US Army Air Force destroyed the Akashi engine plant. Only 374 Ki-61-II-KAI airframes were built in slightly less than a year but some thirty were destroyed on the ground prior to delivery to Service units and 275 were left without engines until the successful adoption of the Mitsubishi Ha-112-II fourteen-cylinder radial engine which gave birth to the Ki-100. Prior to this conversion it had been proposed to incorporate various modifications in a new version, the Ki-61-III, but only one aerodynamic prototype was built, this aircraft being characterised by having a cut-down rear fuselage and the fitting of an all-round vision canopy to a modified Ki-61-II-KAI.

Among the Japanese aces who flew the Ki-61 was Major Shogo Takeutchi. He flew with the 68th Sentai over New Guinea and claimed 16 enemy aircraft destroyed before being killed in a crash-landing on 21 December, 1943.

Plagued by engine troubles and production difficulties, the Hien never saw as extensive a Service use as the more numerous Nakajima fighters, but during the mid-war years it was the only Japanese aircraft which could successfully engage the fast Allied fighters by combining some of the Nipponese machines’ traditional manoeuvrability with a strong and well protected structure.

Units Allocated

17th, 18th, 19th, 23rd, 26th, 28th, 37th, 55th, 56th, 59th, 65th, 68th, 78th, 105th and 244th Sentais. 23rd and 28th Dokuritsu Dai Shijugo Chutais. 8th Kyo-iku Hikotai. 5th,11th, 16th and 18th Lensei Hikotais. Akeno Fighter Training School.

Technical Data

Manufacturer: Kawasaki Kokuki Kogyo KK (Kawasaki Aircraft Engineering Co Ltd).

Type: Single-engined interceptor fighter and fighter bomber.

Crew (1): Pilot in enclosed cockpit.

Powerplant: (Ki-61- prototypes) One 1,100 hp Kawasaki Ha-40 twelve-cylinder inverted-vee liquid-cooled engine, driving a three-blade constant-speed metal propeller; (Ki-61-Ia, -Ib and KAIc and KAId)) One 1,100 hp Army Type 2 (Kawasaki Ha-40) twelve-cylinder liquid-cooled engine, driving a three-blade constant-speed metal propeller; (Ki-61-II and II-KAI) One Kawasaki Ha-140 twelve-cylinder liquid-cooled engine, driving a three-blade constant-speed metal propeller.

Armament: Two (Ki-61-Ia) fuselage-mounted 12.7 mm (0.5 in) Type 1 machine-guns and two wing-mounted 7.7 mm (0.303 in) Type 89 machine-guns; two (Ki-61-Ib) fuselage-mounted 12.7 mm (0.5 in) Type 1 machine-guns and two wing-mounted 12.7 mm (0.5 in) Type 1 machine-guns; two (modified Ki-61-Ia and -Ib) fuselage -mounted 12.7 mm (0.5 in) Type 1 machine-guns and two wing-mounted 20 mm (0.79 in) Mauser MG 151/20 cannon; two (Ki-61-I-KAIc, Ki-61-II and -II-KAIa) fuselage-mounted 20 mm (0.79 in) Ho-5 cannon and two wing-mounted 12.7 mm (0.5 in) Type 1 machine-guns; two (Ki-61-I-KAId) fuselage-mounted 12.7 mm (0.5 in) Type 1 machine-guns and two wing-mounted 30 mm (1.18 in) Ho-105 cannon; two (Ki-61-II-KAIb) fuselage-mounted 20 mm (0.79 in) Ho-5 cannon and two wing-mounted 20 mm (0.79 in) Ho-5 cannon.

External stores: Two 200 litre (44 Imp gal) drop tanks, or (Ki-61-I KAI and -II KAI) two 250 kg (551 lb) bombs.

Dimensions: Span (Ki-61-Ib, -I-KAIc and -II-KAIa) 12 m (39 ft 4 7/16 in); length (Ki-61-Ib) 8.75 m (28 ft 8 1/2 in), (Ki-61-I-KAIc) 8.94 m (29 ft 4 in), (Ki-61-II-KAIa) 9.16 m (30 ft 0 5/8 in); height (Ki-61-Ib, -I-KAIc and -II-KAIa) 3.7 m (12 ft 1 11/16 in); wing area (Ki-61-Ib, -I-KAIc and -II-KAIa) 20 sq m (215.278 sq ft).

Weights: Empty (Ki-61-Ib) 2,210 kg (4,872 lb), (Ki-61-I-KAIc) 2,630 kg (5,798 lb), (Ki-61-II-KAIa) 2,840 kg (6,261 lb); loaded (Ki-61-Ib) 2,950 kg (6,504 lb), (Ki-61-I-KAIc) 3,470 kg (7,650 lb), (Ki-61-II-KAIa) 3,780 kg (8,333 lb); maximum (Ki-61-Ib) 3,250 kg (7,165 lb), (Ki-61-II-KAIa)3,825 kg (8,433 lb); wing loading (Ki-61-Ib) 147.5 kg/sq m (30.2 lb/sq ft), (Ki-61-I-KAIc) 173.5 kg/sq m (35.1 lb/sq ft), (Ki-61-II-KAIa) 189 kg/sq m (38.8 lb/sq ft); power loading (Ki-61-Ib) 2.51 kg/hp (5.53 lb/hp), (Ki-61-I-KAIc) 2.94 kg/hp (6.48 lb/hp), (Ki-61-II-KAIa) 2.52 kg/hp (5.56 lb/hp).

Performance: Maximum speed (Ki-61-Ib) 592 km/h (368 mph) at 4,860 m (15,945 ft), (Ki-61-I-KAIc) 590 km/h (366 mph) at 4,260 m (13,980 ft), (Ki-61-II-KAIa) 610 km/h (379 mph) at 6,000 m (19,685 ft); cruising speed (Ki-61-Ib) 400 km/h (249 mph) at 4,000 m (13,125 ft); climb to 5,000 m (16,405 ft) in (Ki-61-Ib) 5 min 31 sec, (Ki-61-I-KAIc) 7 min, (Ki-61-II-KAIa) 6 min; service ceiling (Ki-61-Ib) 11,600 m (37,730 ft), (Ki-61-I-KAIc) 10,000 m (32,810 ft, (Ki-61-II-KAIa) 11,000 m ( 36,090 ft); range – normal (Ki-61-Ib) 600 km (373 miles), (Ki-61-II-KAIa) 1,100 km (684 miles), – maximum (Ki-61-1b) 1,100 km (684 miles), (Ki-61-I-KAIc) 1,800 km (1,120 miles), (Ki-61-II-KAIa) 1,600 km (995 miles).

Production: A total of 3,078 Ki-61s were built by Kawasaki Kokukai Kogyo KK in their Kagamigahara plant as follows:

12 Ki-61 prototypes – 1941-42

1,380 Ki-61-I production aircraft – August 1942-July 1944

1,274 Ki-61-I-KAI production aircraft – January 1944-January 1945

8 Ki-61-II prototypes – August 1943-January 1944

30 Ki-61-II-KAI prototypes and pre-production aircraft – April-September 1944

374* Ki-61-II-KAI production aircraft – September 1944-August 1945.


Out of 374 Ki-61-II airframes built 275 were completed as Ki-100-Ia.