Exploring the Defensive and Symbolic Purposes of Japanese Castles
From the beginning of the recorded history of Japan, there has been mention of primitive fortifications designed to defend against enemy attacks. They were primarily simple structures made of easily accessible materials such as earth, stone, and wood. As a result of the changing military strategies and security needs, these early fortifications evolved over time and are believed to be the forerunner of castles. The origins of Japanese castles can be traced back to the medieval period, particularly to the latter half of the fifteenth century. During the Sengoku period (1467-1603), these castles played a crucial role in the turbulent era of civil war and political combat. In this period, central Japan was divided and ruled by many warlords, or daimyo. Architectures were used to “physically, visually, and psychologically” express the social structure of Japanese society at that time. The construction of castles became increasingly important as a means of defense and control for the ruling class. Many powerful daimyo built elaborate castles to protect their domains and to establish their centers of administration and military operations. These castles were strategically located to control the transportation of natural and military resources. The architectural design and strategic placement of Japanese castles not only defended against external threats but also facilitated the consolidation and projection of power by ruling clans, shaping the political and social landscape of pre-modern Japan.
The Japanese castles that still exist today are indeed the witness of a long time of military revolution and transformation of power among the ruling class. Throughout Japan’s history, the causes of national instability and threat mainly came from internal rebellions. As the Japanese landscape is predominated by forests and mountains, the earliest fortresses in Japan incorporated both factors in their designs. Mountaintop or hilltop sites provided both defensive advantages and easy access to building materials that were needed to strengthen their natural positions. This style is known as yamashiro or mountain castle. The design and construction of Japanese castles further evolved in response to changes in warfare tactics. As new weapons and attacking techniques emerged, castles were modified and reinforced to react to these situations, resulting in the development of more complicated defensive systems. Traditional fortifications made of wooden and earthen materials were replaced by more effective elements, such as stone walls, moats, and multi-tiered towers. Starting from the late Sengoku era, daimyo wanted to build more permanent strongholds since they were facing constant warfare. Hence, they began to locate their castle on plains or “low plateaus to command valleys and protect nearby rice fields.” Towns were built up around these castles, providing spaces for artisans, merchants, and samurais to reside so they would have opportunities to serve the daimyo. These new types of settlements are referred to as jokamachi (castle town). The new jokamachi symbolized “the new concentrations of military and political power achieved by the daimyo.” Defenses that were formerly scattered around were now arranged to a single central site in which the resources of the ruler could be accessed readily in a more secure way. Among over five thousand castles that once existed in Japan, Himeji Castle is no doubt the most complete castle still in existence (Fig. 1). It was also the largest castle complex, with 83 buildings and covering 576 acres. Such a large scale “reflects the power and wealth of their builders, as well as the intensity of the warfare that swept across all of Japan at the time.” It perfectly exemplifies the multifaceted defensive architecture of Japanese castles, showcasing a series of features designed to fortify, impress, and intimidate.
The location and terrain of Japanese castles played a critical role in their defensive strategy and overall effectiveness. Castles were often situated on elevated terrain, such as hills or mountains, which provided commanding views of the surrounding area. This elevated position provided advantages in battles, enabling the castle defenders to observe approaching threats. Additionally, in most cases the daimyo selected locations where “their castles could dominate the wide plains which formed the economic bases of their power and from which they could control the lines of communication stretching into the countryside.” Japanese castles were also purposefully located near important transportation routes, such as rivers, roads, or coastlines, to control movement and access to resources. Such particular placement allowed rulers to project their influence and power over nearby areas. For instance, Himeji Castle is situated on a hilltop known as Himeyama, which rises approximately 45 meters above sea level. The hill itself is centrally located within the city of Himeji—a place that was once a vital hub that facilitated the movement of goods and military resources. During medieval Japan, the Himeji Castle site was an extremely important strategic point because it connected the west and east parts of Japan. To prevent the west lords from rebelling against his government, Tokugawa Ieyasu used castles to impress and intimidate his allies and enemies. The lords from the west were forced to pass Himeji on their way to Edo to serve the Tokugawa family. The castle was thus utilized to express visually the political and military power of the Tokugawa family.
The most noticeable common feature of Japanese castles was their overall style: “The keep lay at the highest point of the area enclosed by the castle and was surrounded by a series of interlocking baileys.” They were built in labyrinths and “designed to confront an attacking force with an intricate array of deceptive defenses.” The moats, outer walls, and watchtowers were the first layer of protection (Fig. 2). Many Japanese castles were surrounded by wide, water-filled moats to impede enemies. Moats served as barriers against direct assaults and avoided siege tactics such as digging tunnels. Some moats were also filled with spikes or other obstacles to prevent and frighten intruders. The three moats surrounding the Himeji Castle are extensive, measuring approximately 14 meters wide and 6 meters deep on average. They prevent the enemy from rapid approach because of the time needed to transport necessary supplies across the water. Thus, the strength of the enemies would be largely diminished after they had crossed the three moats. The area encircled by moats and outer walls was divided into multiple courtyards and defensive zones that were arranged in concentric circles, each serving a specific function in the event of an attack. They were isolated from each other by ramparts and walls. Once entered these baileys, attackers found themselves trapped in “maze-like passageways designed to confine and confuse them while castle defenders peppered them with musket fire and arrows.” The Himeji Castle has 21 gates and labyrinthine walkways that made it almost impossible for enemies to locate themselves within the compounds (Fig. 3). The number and design of the baileys varied, but there were usually three to five. The outermost layer of the castle complex is the sannomaru. This area served as the first line of defense against potential attackers. It was primarily a buffer zone, containing storage facilities, and quarters for low-ranking samurai and servants. The ninomaru is the second layer of defense within the castle complex. It housed more important structures, such as the residences of high-ranking samurai and administrative offices. At the heart of Himeji Castle lies the honmaru which is the inner bailey. It served as the main residence of the castle lord and contained the central keep, called tenshu. The keep towered over the surrounding buildings and provided a clear view of the entire castle complex. The sophisticated layering design of the compounds ensures that if any line of defense was captured, it could be recovered from another line.
Castles were protected by walls made of stone, earth, or a combination of both. These walls were often several meters thick. They were constructed using multi-layered materials including stone foundations, wooden frameworks, and earthen embankments. This layered construction method helped absorb impacts from attacks and provided stability against earthquakes and other natural disasters. The walls of the Himeji Castle are covered in white plaster, giving it a pristine appearance and serving as a symbol of purity and elegance. Walls inside the Himeji Castle are constructed on top of the stone bases and the foundations (Fig. 4). The foundations at the very bottom consist of soil. It seems that the walls look as if the stones were placed in a random manner, but in fact, they followed “a very careful geometric arrangement that the stones settled into a compact solidness through their own weight.” Large stones formed the main part of the stone foundation, and the gaps between them were filled with smaller stones to ensure the stability of the wall. Moreover, they are designed with a gentle slope, which makes it more difficult for attackers to climb up the castle. Openings in the walls, such as arrow slits and small windows, are positioned to allow defenders to shoot arrows, guns at approaching enemies. The holes provided for arrows were rectangular, while those for guns were circular, triangular, or square. These defensive openings are carefully spaced and angled to provide maximum coverage of the surrounding terrain. Behind the small walls a row of trees, usually pines, would be planted. In one way, these towering trees would act as a shield from arrows and bullets; in another way, they could also provide timber in the case of a prolonged siege. The towers built upon the castle walls not only served as defensive structures but also embodied the strategic vision of their builders. Gatehouses served as the primary entry and exit points of the castle. They often feature elaborate defensive mechanisms such as heavy wooden doors and drawbridges and were typically fortified with guardrooms. The combination of multiple layers of walls and necessary towers transformed the castle into an impregnable military base.
In Japanese culture, architecture is significantly used to express “the social status of their residents and the hierarchical status of the activities that took place inside the buildings.” Such tradition is also reflected in the construction of castles. The largest tower of all Japanese castles is the tenshu, the main keep. Undoubtedly, its height is the most noticeable characteristic to people. Oda Nobunaga, the first “Great Unifier” of Japan, created the concept of tenshu—a symbolic building to showcase the power of the lord and to intimidate allies or enemies. By using an architecture recognizable from far away, daimyo were able to use the keep to symbolize and express their power. Keeps were typically multi-story structures made of wood and stone. The keep of Himeji Castle is a six-story tower, including the basement (Fig. 5). The main tower was differentiated from the rest of the complex through its luxurious architectural style. Unlike other sections of the castle, the windows and roofs of the keep were arranged in more intricate patterns. The windows of a keep were square and the top floor was often decorated with ornate windows in the shape known as kato mado with an exterior balcony. The shape of the keep’s roofs was designed in the style that had been used for centuries only for the most palace-like residences. They were paved with thick blue-gray Japanese tiles to create a strong color contrast with the whitish outer wall of the keep.
Castles serve as evidence for an especially unrest era in the history of Japan. To protect and fortify their domains, federal lords, known as daimyo, had incorporated various innovative defensive systems to intimidate and deter intruders. By the late Sengoku period, castles also played their symbolic roles—they became manifestations of the social status and power of their owners. The architectural features and designs significantly aligned with their primary purpose of defending against potential threats. Meanwhile, they symbolize the power and dominance of different ruling clans, offering contemporary viewers insights into the social and political structures of pre-modern Japan.
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