All castles of the ‘developed’ style (those with stone bases and a complex of buildings) had certain design elements in common, which may be usefully explored by looking at a typical castle of the period, such as Hikone or Matsue, from its overall layout to the roof of its keep.
The first feature common to all the Japanese castle sites was an overall style whereby the keep lay at the highest point of the area enclosed by the castle and was surrounded by a series of interlocking baileys. The general term for the numerous courtyards and enclosed areas formed by this kind of layout was kuruwa. Some were on the same level, paths and staircases linked others, and the way in which the kuruwa related to each other was one of the first points to be taken into consideration by the castle designer. He adopted a method of planning known as nawabari, which literally meant ‘marking with ropes’. As the term implies, this referred to the very practical first step in designing a castle, which was to mark out the future extent of a castle using ropes.
One of the most important considerations for a castle’s defensive system was how these kuruwa would provide an overall defensive pattern for the castle, a matter that was often determined by the local topography. Rivers, mountains and the sea all set limits on the scope of a design. Nagashino castle, site of the famous siege and battle of 1575, was built on a triangular rock where two rivers joined. Takamatsu and Karatsu used the sea as their moats, while Takashima and Zeze used Lake Suwa and Lake Biwa respectively to provide water defences in a style sometimes called fujô, or ‘floating castles’. Inuyama utilises a river and a high mountain as two natural defensive elements, while Bitchu-Matsuyama gazes down from the highest castle hill in Japan.
The central area of the kuruwa, which is frequently all that has survived in many castles, was the most important in terms both of defence and display. Its core was called the hon maru (main or innermost bailey) and contained the keep and any other residential buildings for the daimyô’s use. The second courtyard was called the ni no maru (second bailey) and the third was the san no maru (third bailey). The expression ‘maru’ has survived to this day in the form of addresses in old castle towns. Many have an area of the city called Marunouchi, in other words ‘the area inside the maru’. Tokyo’s Marunouchi district, for example, lies between the imperial palace and Tokyo Central Station.
Many Japanese cities have an area called Marunouchi, in other words ‘the area inside the maru or bailey’. Tokyo’s Marunouchi district is shown here. It lies between the imperial palace and Tokyo Central Station.
The three common styles of castle layout, from top to bottom: rinkaku (concentric); renkaku (offset) and hashigokaku (tiered).
Tokyo provides an extreme example of a castle’s outer works having disappeared under modern development, and the ground plans of earlier castles are sometimes all we have to go on when it comes to determining the layout that a castle once possessed. Archaeology and field observation can give further clues, and the resulting layout designs may be classified as follows:
The rinkaku style has the hon maru in the centre and the ni no maru and the san no maru arranged in concentric rings around it. Although this may seem to be the ideal style for the defence of the hon maru, there are surprisingly few examples of this type of castle. There are two possible reasons for this. Firstly, the moats and stone walls of such a castle had to be extremely long compared the small area on which the hon maru was built. Secondly, such defence works were very labour intensive and therefore very costly. The ruined Shizuoka and Tanaka castles follow this style, while mighty Osaka is the nearest surviving approximation of it.
The renkaku style has the hon maru in the centre with the ni no maru and the san no maru on either side. When building a castle of this style, it was necessary to provide extra protection for the more exposed hon maru. Mito and Sendai are examples of the renkaku style.
In the hashigokaku style, which can only apply to a yamashiro setting, the hon maru forms the apex of the castle while the ni no maru and the san no maru descend in steps like a staircase. As the hon maru is exposed on one side, it needs to back onto a lake, river or cliff. Aizu-Wakamatsu, site of fierce resistance during the Meiji Restoration, is an example of hashigokaku style, while Inuyama on the Kiso has a dramatic cliff on the hon maru side.
The maze of walls and gates that make up the defences of Himeji castle, 1611
One of the most important defensive elements in the developed style of castle was the need to make the approach to the keep as difficult as possible. The ultimate example is the maze created by the succession of walls, gates and baileys at Himeji, which can still be enjoyed today. The successive gates are labelled in the Japanese alphabetical system of ‘i, ro, ha, ni, ho, he’, although some of the final Water Gates no longer exist. Only the ‘upper route’ is described, though there was also a lower route that was even more fiendish.
On proceeding north through the San no maru (Third Bailey) we come to the imposing gate known as the Hishi Gate, but this is just the beginning of a long journey before we enter the keep, during which we will be under observation the whole time and will travel in a spiral. Straight ahead and a little to the left is the first of the alphabetical gates, Gate I, from which we proceed, again in straight line but a little to the right this time to Gate Ro. We cannot see Gate Ha from here, and if we go straight on there is a dead end. Instead we must go to the left, and here the path forks. The left fork leads into the Nishi no maru (Western Bailey) and ultimately back outside Gate I, but we want the right fork for Gate Ha, from where the keep looks so near one could almost touch it. But this is where the labyrinth really begins, because to get from Gate Ha to Gate Ni we have to make a 180-degree turn round the end of a wall, and follow a very narrow approach. Passing through the menacing Gate Ni, where the gate is so much smaller than its gatehouse would suggest, we must make sure we do not miss little Gate Ho, or there will be another dead end. After Gate Ho we turn right round the far corner of the keep through Gate He, and then through one of the surviving Water Gates into the Inner Bailey, bare now, but which had other buildings in it in 1611. We climb up some steps to the remains of the Fourth Water Gate and enter the final gate to the keep that is the Fifth Water Gate. This is the strongest of all and is almost invisible until you arrive at it, being located under the bridging tower between the keep and the north-western tower.
The developed style of castle had a maze of interlocking walls and gates that would confuse an enemy and allow him to be observed for every inch of his way up to the keep. Himeji, with its 21 gates and labyrinthine walkways that literally turn back on themselves, is the perfect example, and its outerworks are seen here.
In the case of a larger castle, the three maru would in turn be encircled by two or three outlying kuruwa referred to as sotoguruwa or soguruwa (the outer courts). Each of these successive areas was so arranged that any line of defence captured by an enemy could readily be recaptured from the area inside it. The ultimate result was a maze of interlocking walls and gates that would confuse an enemy and allow him to be observed for every inch of his way up to the keep. Himeji, with its 21 gates and labyrinthine walkways that literally turn back on themselves, shows this principle to perfection, and will be described in detail later.
The successive kuruwa and maru were divided from one another by moats, ditches and two sorts of walls, the smaller ones on top of the stone bases and the bases themselves, which presented a wall-like outer surface of roughly hewn and partly dressed stone. No mortar was used, making them the world’s greatest dry stone walls. At first sight the walls look as if the stones were placed haphazardly, but in fact they followed a very careful geometric arrangement whereby the stones settled into a compact solidness through their own weight. The outward curve, if any, is concave in shape, resulting from the stones being placed with their smaller sides outwards and their larger sides inwards, although earlier examples tend to be straighter.
Behind these large stones, and rarely seen, are two layers of pebbles that were settled into the excavated earth core of the wall and base. Smaller stones were also used to fill up gaps in the outer wall surface. In cross section a castle’s stone base is wedge shaped, and some reach a height of 130 feet. What made up a castle’s foundations, therefore, was a series of these stone bases holding up towers and gateways linked by other sections which only housed low walls of plaster on top of them. Nevertheless, all these stone bases were of a similarly formidable thickness, and their outer surface projected in and out to give well-constructed and overlapping defences.
The small walls of plaster and ground rock on top of the bases were surprisingly solid, and would be pierced with openings – triangular for guns, rectangular for arrows. These walls add greatly to the aesthetic appeal of the castle. The white walls of Himeji are quite splendid, and the black ‘long wall’ of Kumamoto is a tremendous architectural feature. As they were small, these minor walls were frequently buttressed using wood or stone. Behind the small walls a row of trees, usually pines, would be planted. These would act as a shield from arrows and bullets, but could also provide timber in the case of a prolonged siege, and added greatly to the decorative effect that was in any case part of the overall plan. Within the outer walls trees were also planted to veil the movements of soldiers within the defences and to provide a food source.
The magnificent stone bases that make up Kumamoto castle are among the largest in Japan, and from inside the dry moat they even seem to dwarf the mighty keep.
Built up on top of the stone bases were the small white walls pierced with triangular gun ports and rectangular arrow ports as shown here at Himeji.
Roadways were provided to give access to the castle complex from outside. Sometimes these were conveyed across bridges, otherwise through a smaller version of the stone bases described above. The entrance at the front of the castle was usually called the ote (meeting place), while the gate it leads to was known as the ôtemon. The passage on the postern was called the karamete, meaning ‘the place where prisoners will be captured’, because postern gates were used as sally ports for surprise attacks.
Bridges came in many different styles. They were usually of wood, although Fukue castle on the Goto islands provides an unusual example of a stone bridge. Of the fixed wooden bridges, most tended to be of cantilevered construction and could be very graceful. The ones at Hikone and Matsumoto are particularly pleasing examples. No actual drawbridges appear to have survived anywhere in Japan, but we know they existed from drawings and descriptions, although they were very rare. A variation on the conventional European drawbridge was also found in Japan. This was a removable bridge that could be rolled out on wheels across a gap along very narrow horizontal supports.
Of the buildings that were part of a castle’s superstructure, the ones that a visitor first encountered were the gatehouses. A castle gatehouse would make up quite a complex micro-system of defence. A pair of gateways would cover entrances. The first was directly open onto the roadway, and sometimes had small roofs projecting outwards on the forward support of the gate. The second, inner, gate would be set at right angles to the first so that an attacker would have to make an abrupt turn. In the case of castles built on a hill the second gate would often be positioned so it was higher than the first, a feature shown very well at Hikone. Whatever the arrangement, there was always a roughly rectangular-shaped area between the gates that was fully enclosed and overlooked from all points. This space was called the masugata, from the shape of the measuring vessel (masu) commonly used for liquids and grain. Another meaning of the term derives from the fact that a castle commander could assemble his men in sections in this area and thereby count them. Small, so-called uzumi or ‘secret gates’ also appear in concealed places along the walls. The actual gates that were hung in the gatehouses were of heavy timber on massive iron hinges, and were reinforced with iron plates and spikes.
The black and white ‘long wall’ of Kumamoto castle is the finest example of the small wall, and provides one of the outstanding architectural features of this castle.
Fukue castle on the Goto islands provides an unusual example of a stone bridge. It leads to a simple castle gate.
The high wooden bridge of Hikone castle, which featured in the film Shogun.
Of the buildings that make up a castle’s superstructure, the ones that a visitor would first encounter were the gatehouses. A castle gatehouse would make up quite a complex micro-system of defence. Entrances would be covered by a pair of gateways. The first was directly open onto the roadway, as shown here at Wakayama.
The second, inner, gate would be set at right angles to the first and was often of a two-storey construction, so that an attacker had to make an abrupt turn. In the case of castles built on a hill the second gate could be higher than the first, a feature shown here at the Taiko Gate of Hikone.
Gatehouses that were built in the form of a tower were called watari yagura, meaning ‘the tower that bridges both sides’. Yagura was in fact the generic name for a tower; the word literally means ‘arrow store’, which was one of their original functions. However, yagura in a Japanese castle could take many different forms apart from the conventional Western understanding of the word ‘tower’. One common variety was the tamon or tamon yagura, which was a long one-storey building set on top of a stone base acting as a defensive wall, a lookout post and a utility building all in one. The name may derive from Tamon castle, which was built by Matsunaga Hisahide and where such a structure was effectively the first Japanese castle keep. The fine tamon yagura at Hikone was used by the maidservants as living quarters.
Detail of the gate hung in one of the gatehouses at Tottori castle, showing iron reinforcements and spikes.
The tamon yagura at Hikone, showing the finest example of the tamon style of tower, which combined the functions of tower, outbuilding and wall in one structure.
At the corners of the walls may be seen other towers of two or three storeys. Known simply as sumi yagura (corner towers) they comprised an important element in the overall castle design. Corner towers were often fitted with ishi otoshi (stone droppers), which were the Japanese equivalent of machicolations. The Inui tower of Osaka castle, which lies at the northwest corner of the complex, has the unusual feature of having two storeys of equal size. Matsumoto castle has a subsidiary tower that is open on the eastern and southern sides. Called the Tsukimi tower, it was not designed as a military structure, rather for moon-viewing.
The largest tower of all in a Japanese castle is the tenshu kaku or keep. The name means ‘high heavenly protector’ and height is usually the first characteristic that is noticed. In many cases, in fact, the keep will have caught the visitor’s eye long before he appreciates the gates or corner towers, because the keep is almost invariably the highest point of the entire structure and may be visible for miles. In some cases only the keeps of Japanese castles have survived, which can give a misleading impression of the original design of the fortress. Inuyama and Maruoka castles display the earliest features of the Japanese keep.
A typical keep would be of at least three storeys, maybe even as many as seven, but frequently their outward appearance did not correspond exactly to their actual interior structure and design because there were often underground cellars built deep inside the stone core of the base and the number of floors above ground was often not discernible from the apparent number visible from outside. The purposes of a keep included the following key functions:
1. To provide a vantage point
2. To act as the final line of defence
3. To symbolise the daimyô’s power
4. To provide secure storage.
As the Portuguese Jesuit Joao Rodrigues put it:
They keep their treasure here and it is here that they assemble their wives in time of siege. When they can no longer hold out, they kill their women and children to prevent them falling into the hands of the enemy; then after setting fire to the tower with gunpowder and other materials so that not even their bones or anything else may survive, they cut their bellies.
Azuchi castle, 1576
Only a stone base remains of the great Azuchi castle, raised by Oda Nobunaga in 1576 as one of the wonders of Japan. It was Japan’s first great tower keep and was burned to the ground when Nobunaga was assassinated only six years later. For this reason no one can be sure for certain what Azuchi actually looked like, but the consensus of opinion is that this revolutionary building had seven storeys, of which the uppermost one was octagonal and richly decorated. Military corridors inside surrounded domestic areas
This view of the keep of Himeji shows several important features. First is the use of two styles of gables. The first style, chidori hafu, is roughly triangular in shape. The second, kara hafu, is curved, with the apex flowing into the line provided by the cornice. There is also a prominent stone-dropping hole on the outer corner.
The first tower keeps (including the original one at Himeji, demolished in 1601) were less ornate structures, resembling larger versions of the simpler corner towers, however, when embellished to the extent revealed by many surviving examples they make dramatic statements of a daimyô’s power. Unlike almost anywhere else in the castle, the windows, roofs and gables of the keep were arranged in subtle and intricate patterns. The shape of the keep’s roof was almost without exception in the ornate style that had been used for centuries for the most palatial residences, and the use of two contrasting styles of gable on the same elevation of a keep was also a frequently noticed aesthetic element. The first style, chidori hafu, was triangular in shape. The second, kara hafu, was curved, with the apex flowing into the line provided by the cornice. This style of architecture can be seen to good effect at Himeji.
It is rare to have a view of the roof of a Japanese castle’s keep from above, but this is provided here by the reconstructed Fushimi Momoyama castle near Kyoto.
The windows of a keep were generally square, though the uppermost storey was often provided with ornate windows in the shape known as kato mado, and usually had an exterior balcony. Roofs were almost always tiled with thick blue-grey Japanese tiles, though in the early days some castles had thatched roofs, and old photographs of Iwakuni castle confirm that it was once roofed with wooden shingles. The ridge of the topmost roof of the keep was also usually decorated with shachi (dolphins) made of metal or tile. These striking ornaments in the shape of fish are supposed to be charms against evil spirits and fire. They are sometimes gilded, and there is a charming story told about the shachi on the roof of Nagoya castle, which were made from a core of cypress wood covered in lead and copper, and finally coated with pure gold. A thief had himself floated up by means of a kite to steal the gold scales from the fish!
This view looking across Osaka from the uppermost storey of the castle keep shows the layout of the inner wet moat and one of the golden shachi, the so-called ‘dolphins’ that protected the building from fire.
The entrance to the keep of Maruoka castle is accessed by means of a long stone ramp built into the stone base. This keep dates from 1576.
At Bitchu-Matsuyama a long climb provides the reward of seeing stone walls integrated superbly with the natural rock.
The external colour of surviving keeps is usually white; however, this was not necessarily their original colour. Both Azuchi and Osaka are known to have sported bright colours and designs of tigers and dragons on their exterior surfaces. The exceptions are the so-called ‘black castles’ such as Kumamoto and Okayama, where the predominant colour comes from the black wood that dominates the white plaster around with only the mon (family crest) of the daimyô carved on the apex of the gable ends for decoration.
In some cases topographical considerations led to the construction of keeps of unusual shapes. The ideal shape for a stone base was rectangular, but this was not always achievable, especially when the base had to be built round the core of an extinct volcano, as is the case with Wakayama castle. In spite of intensive cutting away of the hill top, the resulting area was so limited that the keep had to be rhombic in plan with all corners of the building curved, while the small tower adjacent to the keep was built on an irregular pentagonal first storey. At Kumamoto castle the first storey actually overhangs the stone base so as to give a rectangular shape, and the extra space created was used to provide an area for dropping stones. At Bitchu-Matsuyama a long climb provides the reward of seeing stone walls integrated superbly with the natural rock, inside which the complex housing the keep makes the best possible use of the restricted space available.
The stages of building the stone base of a castle.
1. The hillside is carefully carved away, staggered for safety.
2. The vital ne ishi (root stones) are laid in the precise position determined by wooden supports.
3. While wooden scaffolding and walkways allow the workmen to operate in safety, the curve of the wall is followed, with pebbles being rammed behind the line of the outer stone surface.
4. The wall is completed, and the moat is filled.
The building of a pre-stone sengoku yamashiro has been adequately described above, but the construction of a developed stone-clad model complete with tower keep was an altogether different process.
Firstly, the chosen site was surveyed, and the architect designed on paper the best style of castle layout commensurate with the constraints of the site. Before any actual building began, however, there would be a religious ceremony conducted by a Shinto priest. This consisted of ritually cutting the first sod within a sacred enclosure formed by fastening four ropes to four green bamboo poles. From the ropes paper gohei (streamers) would be hung. With the daimyô and his representatives watching, a ceremonial offering of rice and salt would then be made.
This model at Nagahama castle shows several of the stages than went into the building of a castle, from the cladding of the excavated hillside in stone to the raising of the keep. Note the workmen on their cradle platform, and the large stone being wheeled up on a cart.
After this the labourers took over, and under the guidance of supervisors, who would work from the architect’s plans and sometimes even from a relief model, the colossal and labour-intensive business of carving up a mountain would begin. Although the technical term for dividing up the castle site was ‘marking by ropes’, it was stout timbers that provided the lines for the workmen to keep to. After some preliminary ground breaking, a nearly vertical groove would be dug into the hillside to provide the first guideline. The actual line that the outer surface of the final stone wall would follow was provided by a long length of timber projecting parallel to the earth line and about three feet away from it, secured into the position by projecting wooden stakes. About 12 yards further along a similar guideline would be erected. Excavation would then continue between the two markers, which would be joined by other poles horizontal to the ground when the shape was complete. The result would be that one section of the castle was beginning to take its roughly final shape, surrounded by this guidance frame that looked like open wooden scaffolding. In the case of high wall sections different horizontal levels would be staggered. Great care was taken to produce as near perfect an outer surface as was possible, and if there was any danger of collapse the earth surface would be sheathed in wood.
The labourers who worked on the excavation had two main tools, one for digging, an implement resembling an adze, and baskets slung on a pole between the shoulders of two men for carrying away the soil. Because of the danger of rain bringing the fresh excavations down, the next stage, that of adding the stone, was begun before all the site had been carved, so a developing castle site would have shown nearly every successive process in action at any moment.
The delivery to the site of the ordinary building stones (as distinct from the ‘ceremonial’ donated ones described below) was accomplished by various means depending on their size. Two men would carry smaller ones slung from a pole. Bigger ones would be taken on a two-wheeled cart with two men pushing and two others pulling. Oxen would pull carts for even larger varieties.
One colourful feature of the process of building the largest and most prestigious edifices concerned the transportation to the site of huge individual stones that were to be incorporated into the walls. In this model at Hyogo Prefectural Museum a stone ornamented with Hideyoshi’s flags is floated down river on a raft.
The great stone of Osaka castle, incorporated into the walls, shown with the author standing in front of it for scale.
When the stones began to be added to the carved surface the guide poles mentioned above came into their own to provide the target line for the finished product. Careful preparation began at the base of the section under construction. A timber base provided the exact angle for laying the bottom line of stones. The crucial one was the extra-large ne ishi or root stone. This would have its top and bottom surfaces precisely worked to launch the correct angle for the chosen slope – the higher the wall, the lower the angle. Behind the root stone was a layer of compacted smaller stones, and behind them a layer of pebbles pressed into the shaped earth core. From then on wall-building was a matter of adding height to this sandwich of stones and pebbles until the top of the wall was reached. Particular care was taken over external corners, where the specially shaped corner stones ‘dovetailed’.
As the wall progressed upwards structures were put in place for delivering materials to the builders, either by wooden ramps from below, or by lowering baskets of stone from above. The workmen toiled on top of wooden platforms laid along the ever increasing upper surface of the wall. The smaller stones were pounded into a compact mass using wooden drivers.
The placing of the outer layer of stones required much effort and great precision, particularly when the largest stones were added. One colourful feature of the process of building the largest and most prestigious edifices concerned the transportation to the site of huge individual stones that were to be incorporated into the walls. In cases such as the building of Hideyoshi’s Osaka castle the daimyô vied with each other as to who could donate the largest stone. The arrival of these monsters at the site was always a source of celebration, and numerous contemporary illustrations depict some massive piece of rock being dragged on a sledge, or towed along on a barge. The stone would be festooned with banners and religious objects as if it were a portable shrine in a religious festival. The labourers heaved on the ropes while small boys balanced on top of the stone waved fans and led the rhythmic chanting. One colossal stone at Nagoya castle has an outside surface area of 54 square feet, and was donated by Kato Kiyomasa. The huge stones of Osaka still provide a tourist attraction today, but recent excavations have revealed that some of these giants are not all that they appear to be. One, which is thirty feet long and ten feet high, turns out to be only about two feet thick!
Once the stone base was complete a very different building process would begin to raise the superstructure of the small walls, the gatehouses, side towers and above all the keep. Here the key material was wood, and the amazing skills of the Japanese carpenter who could build pagodas and temples came into its own. Within a scaffolding constructed from long wooden poles, a huge timber framework would take shape. The vertical sections were sunk deep into the untouched core of the original hill, where they rested upon massive rocks placed there as foundations. Plaster was applied to the coarse framework between the pillars to give the outer surface to the buildings in a similar way to the building of the low plaster walls already described. Alternatively, in the case of the ‘black castles’ of Kumamoto and Matsue, the external surface would be of painted wood. Tiling, decoration and gilding, topped off with the traditional golden shachi, were the final stages used to produce the external appearance of the mighty edifice. Such were the human and financial resources available to a daimyô that the whole process from excavation to completion could take a surprisingly short space of time. Nagoya castle, for example, was completed for the Tokugawa shogun after only two years.
Whatever their aesthetic appeal, Japanese castles were primarily fortresses, and the Japanese castle represented a sophisticated defence system, even if the way this operated is not always directly apparent. At first sight the graceful superstructures look flimsy and very vulnerable to fire, but they were in fact highly fire resistant, and the Japanese also lacked the means for effective artillery bombardment until quite late in their history.
One obvious disadvantage provided by the gently sloping and curved walls of the typical castle stone base was the ease with which attackers could climb them, and the way in which the unmortared blocks of stone fitted together also provided numerous handholds. One solution was the incorporation into the design of towers of the stone-dropping holes noted above which were akin to European machicolations. Unlike machicolations, however, the ishi otoshi were closed by hinged doors. An additional deterrent to would-be climbers were rows of spikes pointing downwards from certain horizontal surfaces such as is seen on the keep at Kumamoto castle and the small walls at Nagoya.
One subtle addition to the defences of the keep at Kumamoto was the rows of spikes like these to stop an assailant from climbing in.
Whereas the primary consideration behind the European angle bastion was protection against artillery fire, this was only one factor taken into consideration in Japan, even though the two styles look superficially similar. In Japan an infantry attack or mining were far more likely to occur than an artillery bombardment, and it is only at the siege of Osaka in 1614/15 that anything resembling a European cannon bombardment becomes a major feature. In this case guns of European manufacture supplied the bombardment, so for this reason alone no Japanese castle can be regarded as an artillery fortress by design. There are no gun emplacements or casemates as such, and there would be few places inside Himeji, for example, where cannon could be mounted successfully. Instead the most common gunpowder weapons would be thousands of arquebuses with which an attacker or defender would sweep his opponent’s lines. This was the technique that won the Korean castles for the invaders of 1592, an invasion army, incidentally, that took almost nothing in the way of an artillery train with it.
The dramatic ‘hairpin bend’ at Himeji found on the approach to Gate ‘Ha’. The keep looks tantalisingly close in the background.
A few attacks on a castle by mining will be illustrated in the ‘operational history’ section that follows, but there appears to be no evidence of permanent counter-mining measures being introduced, as was often the case in Europe. Attacks by flooding were also something that could not be adequately prepared for apart from choosing high ground on which to build one’s castle. The great flooding sieges of Japan, Takamatsu, Ota and Oishi, all made use of very large-scale civil engineering works to create dykes and divert rivers, followed by immense patience as the waters rose, and there was little the defenders could do other than attack the workmen. Many castles would have had moats wide enough to cope with rising water levels, however, although whether the threat of flooding was the reason they were built is hard to discern.
As noted earlier, bombardment from gunpowder weapons was never a major consideration in defensive planning for a Japanese castle until the very end of the period under discussion. Its primitive cousin, bombardment by crossbows and catapults, has a much longer history, but accounts of their use in Japan are sparse. Both forms of missile weapons seem to have been used during sieges, primarily as anti-personnel weapons and secondarily as incendiary deliverers, with wall-breaking only a minor consideration. Crossbows passed out of use late in the 12th century. The catapults used were Chinese-style traction trebuchets, and in fact the best account of their use, which dates from 1468, describes them throwing soft-cased exploding bombs not against a yamashiro’s castle walls but against the samurai defending the rudimentary palisades set up during the Onin War. Traction trebuchets appear in a clearly defensive role for a castle when the Mori family attacked Takiyama castle and were met by smooth river stones loosed from catapults. As late as 1614 traction trebuchets armed with soft-cased bombs were to be found on the walls of Osaka castle.
