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Japanese castles and the lessons of NagashinoBy Stephen Turnbull
The siege and battle of Nagashino in 1575 together make up one of the pivotal events in samurai history. The army of the Takeda clan, who had been besieging the tiny but stubbornly defended fortress for nearly ten days, abandoned their siege lines to assault the army sent by Oda Nobunaga to relieve Nagashino. The great strength of the Takeda was the immense striking power of their cavalry, but when they swept down upon the enemy lines they found themselves faced by 3,000 arquebusiers who had been trained to fire in organised volleys, and who were protected by a loose palisade. The gunfire broke the impact of the initial charge, and as the second wave of horsemen prepared to go in, the gunners calmly reloaded under the protection of their spearmen. Once again the line held, and when the Takeda faltered for a third time the samurai and footsoldiers of the Oda began to engage the attackers in hand to hand fighting. Several hours of conflict followed, at the end of which the Takeda withdrew after taking enormous casualties, broken forever as a military and political influence in Japan. In a very real sense the brief transition between the siege of Nagashino being ended and the battle of Nagashino beginning, a period of time lasting but a few hours, marks an important turning point in the development of samurai warfare. The siege had been a classic of the old style. It was conducted against a traditional and simple style of fortress built from wood and some stone that included in its defence a modest number of arquebuses and only one cannon. Attacks upon it had involved an assault party on a raft floated down the river, mining on the landward side, fire arrows loosed against the wooden buildings, but, above all, repeated assaults on the walls with hand-to-hand fighting. By contrast, the battle which followed a few hours afterwards was the herald of a military revolution, whereby a straightforward tactical charge, the sort that had given the Takeda victories at Uedahara in 1548 and Mikata ga hara in 1572, was stunted by what was in effect a new type of field fortress that combined organised gunfire on a large scale with simple defence works. From this point on Japanese warfare, in particular Japanese defensive warfare, would never be quite the same again. Therefore, although the Nagashino campaign began with a siege, I shall argue that it is to the combination of the guns and fences of the Nagashino battlefield, not the old fashioned stockades and towers of the Nagashino castle, that we must look if we are to understand what brought about the revolution in castle design and warfare that Japan was to see over the next fifty years. The evolution of the Japanese castleThe type of Japanese castle design that Nagashino's fortress represented already had a long history. As the Japanese landscape has always had a shortage of stone and an abundance of trees clustered on forested mountains, it was natural that it should be the latter two factors – timber and high ground, which determined the character of Japanese fortifications for many centuries. The first Japanese castles, therefore, consisted of simple wooden stockades linking towers and gates that followed the natural defences provided by the height and the contours of the mountains from which the materials for the wooden walls had been taken. The erection of palisades on top of earth works, raised by excavating a forward ditch, could compensate for the lack of high ground when a position had to be erected in an area of flatlands, but such topography was avoided wherever possible. It was from the mountain-top yamashiro (mountain castles) of Akasaka and Chihaya, which were built on these principles, that the famous Kusunoki Masashige conducted his spirited defensive campaigns and guerrilla actions between 1331 and 1336. Such designs persisted on into the Sengoku-jidai, the Period of
Warring States, which is commonly accepted as beginning with the ïnin
War of 1467-76. As central authority collapsed those who had been the
Shogun's deputies out in the provinces took the territories they had governed
and made them their own. In this they were challenged, and frequently
overthrown, by a new breed of warlord who owed nothing to ancient privilege
and prestige and everything to their skills in warfare. These men, the
first daimyô (great names), led armies and ruled territories
whose borders were defined solely by their latest conquests, and to defend
their lands they adopted the yamashiro model on a huge scale. From one
honjô (headquarters castle), a network of satellite castles
radiated out, each of which had its own smaller sub-satellite, and with
each sub-satellite having its own local cluster of tiny guard posts. The
network would often also be linked visually by a chain of fire beacons.
For a daimyô's honjô, and for most of the satellite castles, a simple stockade was not enough to withstand enemy attack or to provide barracks space for a garrison, so a technique developed whereby the mountain on which the yamashiro stood was literally carved up. Using the formidable resources in manpower that a successful daimyô could now command, neighbouring mountains were sculpted into a series of interlocking baileys which followed the natural lines only in the sense that the contours provided the guide for the excavation of wide, flat horizontal surfaces, each overlooked by the one above it. The result was a gigantic and bizarre earthwork produced by removing materials rather than piling them up. Some of these highly developed yamashiro could be as much as 200km long, but height was often a more important consideration than width, with successive baileys covering huge areas at different levels. Garrisons could number up to 2,000 men. On top of this framework were placed fences, towers, stables, storehouses, walkways, bridges, gates and usually a rudimentary version of a castle keep. Very little stone was used in the construction except for strengthening the bases of gatehouses and towers and to combat soil erosion from the excavated slopes. As time went by the simple palisades and towers inside the yamashiro were replaced by stronger wattle and daub walls, plastered over against fire attack and roofed with tiles as a protection against rain. By the time of the battle of Nagashino it had also been realised that if the cut away slopes of the natural hills were reinforced with tightly packed stones arranged scientifically so that any weight upon them was dissipated outwards and downwards, then much larger, taller and heavier buildings could be successfully raised on top of them. In some cases artificial mounds were built in this way on flat areas and encased with stone. The result was the beginning of the construction of the earliest form of the castle keeps that are now such an attractive feature of extant Japanese military architecture. It is, however, important to realise that it was the huge overlapping walls made from the carved stone-clad hillsides, rather than any buildings added on top of them, that were the fundamental defining feature of a Japanese castle. The huge tower keeps that now grace such castles as Himeji and Matsumoto were by no means a universal element. The earliest tower keeps date only from the 1570s, and many were not added until early in the seventeenth century. It can also be shown from sources such as painted screens of battle exploits that the majority of the keeps that withstood attack during the time of civil wars would have been of much simpler construction than these magnificent towers. From Nagashino to AzuchiFirearms had been used in Japanese warfare from the late 1540s onwards, but had produced no visible impact in castle design by the time of the siege of Nagashino. None of Nagashino's defences were designed in any way for specific protection against gunfire, or to allow the use of gunfire rather than arrows in defence. It is also unlikely that Nagashino possessed a keep in any form other than a simple two storey wooden building with a Japanese style curving roof, but in one respect Nagashino castle was exceptionally fortunate. It was not built upon a stripped out mountain, but very literally founded on solid rock, a dramatic promontory that marked the confluence of two minor rivers that joined at Nagashino to become the mighty Toyokawa. These rocky cliffs therefore formed two sides of an equilateral triangle, which was completed on its third side by an outer bailey of a simple ditch, mound and palisade construction. This combination of two impregnable rocky sides and the sheer determination of the defenders behind the wall of the third side kept every ingenious Takeda attack at bay, and forced the commander Takeda Katsuyori to settle down for what could be a long wait until the defenders surrendered from starvation. Up to this point the siege of Nagashino had been little different, except in intensity, from a hundred similar actions fought elsewhere in Japan. But then the situation changed. A brave warrior called Torii Sune'emon slipped out of the castle and took a message to Oda Nobunaga, who immediately set out with a relief army. But Nobunaga did not simply fall precipitately on to the rear of the Takeda lines. Instead he halted on a low ridge a few kilometres away. It had a forest to its rear and left, a stream in front, and a river to its right. With the aid of wooden stakes and the massed ranks of his gunners Nobunaga converted the site into an instant castle, and waited for the historic and doomed attack.
The battle of Nagashino was therefore won not from behind the walls of a castle, but from a simple position constructed overnight and defended by guns. So to the trends already visible in the design of those Japanese castles faced with stone that were intended to be permanent bases was added another: the lesson of the effectiveness of something created both temporarily and quickly, and it is remarkable that the development and dissemination of both these strands should be so closely associated with one man: Oda Nobunaga. His successful deployment of firearms was to have a great bearing on both trends, and within a year of Nagashino Japan was to see the first, and perhaps the finest, of the new style permanent military bases/palaces in Nobunaga's castle of Azuchi. This remarkable fortress demonstrated Nobunaga's power in several ways. First, it showed the remarkable effects that could be produced by encasing the excavated hills of a yamashiro in shaped and cut stone. No bare earthen walls were now visible. All was graceful sloping stone, and as well as providing their own defences, these cyclopean mounds allowed the raising of a spectacular seven storey keep ornamented within and without as befitted the grandeur to which Nobunaga now aspired. Around Azuchi's keep were a score of smaller towers, each of which would have done credit as the main keep for a normal sized castle, but Azuchi was huge, built to house the enormous garrison (over 10,000 men) that few daimyô could afford to feed or to arm. Nobunaga could do both, and the internal walls of Azuchi were fitted with numerous racks for hundred of arquebuses, which could be quickly lifted down and poked out through the windows and weapon slits of the towers, all cunningly designed to provide flanking fire from projecting bastions. Azuchi, therefore, may also be regarded as Japan's first artillery fortress, where gunfire was the primary defence, and with its construction Nobunaga demonstrated how his understanding of the use of gunpowder weapons united both battlefield and fortified place. Castles and the Nagashino battlefieldThe second trend associated with Oda Nobunaga, that of using a temporary field fortification either to augment a castle of replace it, continued to influence castle design in parallel with the first strand described above. The rapid dissemination of this second trend can be directly linked to Nagashino, because by strange coincidence the roll call of Oda Nobunaga's army included many of the men who were to be enormously influential in the following years of samurai history. Toyotomi Hideyoshi, Tokugawa Ieyasu and Shibata Katsuie are but three of the movers and shakers of Japanese history who fought shoulder to shoulder at Nagashino and then went on to fight each other with the lessons of Nagashino having been learned dramatically at first hand.
When the battle ended Oda Nobunaga returned to his base at Gifu with much unfinished business to deal with. At the top of his agenda was the final destruction of the warrior monks of the Ikkô-ikki, whose early adoption of firearms had been a precursor to Nagashino. Nobunaga himself had experienced the effects of the mass use of arquebuses at their hands during an attack on their fortified cathedral of Ishiyama Honganji. This, combined with Nobunaga's own earlier experiments with rolling volleys, had led directly to his battlefield layout at Nagashino. Over the next few years the newly confident Nobunaga literally met fire with fire, overcoming the warrior monks finally in 1580. By now Oda Nobunaga had perfected the technique of rotational volley firing, ten years before the idea first emerged in Europe, where the technique is attributed to Count William Louis of Nassau, who set it out (including diagrams) in a letter to his cousin Maurice of Nassau in 1594. He called it the European countermarch, and said that he obtained the idea by studying the similar tactics of missile troops in the Roman legions. Meanwhile Takeda Katsuyori, the loser at Nagashino, showed the lesson that the battle had been for him by making a major strategic U-turn. For half a century the Takeda had won and controlled territory without ever building anything that could be described as a headquarters castle. Tsutsujigasaki, the Takeda capital, was a mansion built on flat ground with little other than a moat and a fence for protection. As Nobunaga's armies closed in on his home province Katsuyori abandoned Tsutsujigasaki for the stone walls of newly built Shimpu. His retainers saw it as a very bad omen, a prophecy that came true with Katsuyori's defeat and death in 1582.
Oda Nobunaga himself followed Katsuyori as a Guest in the 'White Jade Pavilion' before the year was out, and in 1583 his successor Toyotomi Hideyoshi was to be found fighting his former Nagashino comrade in arms Shibata Katsuie at the battle of Shizugatake. Katsuie's general Sakuma Morimasa, another Nagashino veteran, had besieged the mountain fortress of Shizugatake, which, like Nagashino, was holding out stubbornly. On being informed that Sakuma had not abandoned his siege lines for the security of one or other of the yamashiro that he had successfully captured, Toyotomi Hideyoshi advanced on Shizugatake in a rapid forced march. Sakuma's position was Nagashino in reverse. Expecting no response from Hideyoshi for several days he had stayed in the siege lines. Hideyoshi fell upon him before he had a chance to erect any form of field fortifications, and soon his entire army was defeated. Such a failure to benefit from the first hand experience of Nagashino was not shared by Tokugawa Ieyasu, who was the next rival to challenge Hideyoshi for supremacy. Their territories met in Owari province, formerly the Oda heartlands, and it was the way in which their antagonism was resolved that was to show the most dramatic influence from the Nagashino experience. Owari province (much of which now lies within the boundaries of the city of Nagoya) was largely flat, so Ieyasu took the opportunity to secure one of the few pieces of high ground, which was the site of the former castle of Komaki, 86 metres above sea level. As time was pressing Ieyasu's men took to the spade, and raised earth ramparts as Komaki's defences in a few days. Four other forts were also strengthened to provide secure communications to the south and west. Hideyoshi soon heard of Ieyasu's activities and responded in kind. Neither of his two frontline forts of Iwasakiyama and Nijubori had Komaki's advantage of high ground, so, with memories of Nagashino behind him, he ordered the construction of a long rampart to join the two together. The resulting earthwork, probably strengthened with wood, was completed overnight. It was 2km long, 4.1m high and 2.2m thick, and pierced with several gates to allow a counter attack. The slope of the rampart no doubt also allowed for the provision of firing positions. Satisfied with his Nagashino-like front line, Hideyoshi set up his headquarters to the rear at Gakuden. The following morning, upon observing Hideyoshi's rampart, Ieyasu immediately ordered a similar line to be constructed parallel to it and out from Komaki to the south-east. This was a more modest construction only 800 metres long and anchored on the small fort of Hachimanzuka, from where it was a short distance to his communications forts of Hira and Kobata, but the result was that these two veterans of Nagashino were now facing each other from behind the sixteenth-century equivalent of a First World War trench system. It was almost inevitable that the lessons of Nagashino should not only have caused these highly skilled generals to take the defensive measures that they did, but should also prevent either of them from making the first move in attacking each other. The result was stalemate, which was not a situation at all conducive to the samurai spirit, and within a few days there occurred the bloody but indecisive battle of Nagakute. However, Nagakute was not fought between the Komaki lines, but arose from an attempt by one of Hideyoshi's generals to raid Ieyasu's home province while he was sitting in the ramparts of Komaki. Nagakute having been fought some distance away, both armies returned to their lines, and the stalemate began again. Once more boredom set in, and this time it was relieved by Hideyoshi withdrawing more men to besiege Ieyasu's ally Oda Nobuo in his castle of Kagenoi. In fact no frontal attack between the two ever took place at Komaki, and eventually their differences were settled by negotiation and the ramparts were allowed to crumble back into the rice fields. The next example of the use of earthworks combined with guns is to be found during Hideyoshi's invasion of Korea in 1592. The rapid advance of the Japanese up the Korean peninsula stalled following the capture of P'yong-yang, which had been defended by stone walls built in the usual Korean pattern of a long, vertical but narrow construction, not based round an earth core as in the Japanese style. When P'yong-yang came under threat from the expeditionary army sent by the Ming Chinese the Japanese defenders made no attempt to increase the size of the Korean walls. Instead they turned to digging to augment the existing defences of the city by horizontal earthwork bastions. P'yong-yang therefore provides the first example of the construction of recognisable Japanese-style fortifications in Korea. The advancing Chinese, who compared the Japanese efforts unfavourably to their own magnificent Great Wall of China, scorned the crude ramparts, referring to them as 'earth-caverns', and likened them to the primitive earthworks found among the Jurchids of Manchuria. What the Chinese did not realise was that these earth caverns' were designed to provide a clear field of fire for thousands of arquebuses, and to absorb whatever punishment the Chinese cannon could throw at them. In spite of a massive assault by the Chinese army the huge earthworks absorbed all their artillery fire. Those who fought their way to P'yong-yang's gates were then enticed inside and cut down in the maze of streets by Japanese arquebus fire, the attack was abandoned. Further readingBlack, Jeremy (ed.), European Warfare 1453-1815 (1999)
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