A sketch of kogo-ishi remains that have been found. What is Japanese Architecture?p96

There is still much disagreement between historians surrounding the question as to when the building of fortification began in Japan. Two types of remains have been discovered which are believed to have come from fortification structures constructed in the 6th and 7th Century. One of the fortification structures is referred to as chashi and was found on Hokkaido, Japan's most northern island as well as on the north-eastern area of Honshu, Japan's main island.( Hinago Japanese Castles p32) The other, known as kogo-ishi, was discovered in Kyushu, the island to the south of Japan's mainland. Chashi are thought to have been constructed by ancestors of the Ainu, Japan's native people who resided in Hokkaido at the time. They were under constant attack from the Japanese government during the 6th and 7th Century and it is highly likely that the aboriginals built the chashi as a defence against the government. It is widely believed by archaeologists that the chashi consisted of a moat which enclosed the population as well as some small walls.

Kogo-ishi were first believed to be stones which surrounded sacred sights, but after extensive research it was found that the stones were part of mountain fortifications. These mountain fortifications consisted of rows of stones which ran along the side of small hills and reached a number of kilometres in length. In places, the stones were piled quite high resembling a wall. There were also gaps in the row of stones where gates are believed to have existed. Fortifications are believed to have been introduced in Kyushu, due to the ever present threat of attack from Korea and China.( Hinago p32-33) Kyushu was way ahead of the rest of Japan in the area of military preparedness due to this constant threat.

The Heian era (794-1185), saw the rise of the samurai or the 'warrior class', which built up its own armed forces and fought for autonomy. Samurai families hoping to become part of the court moved to the capital, Kyoto, and began their struggle for power. Territorial warlords and samurai fought for supreme power over certain domains, and this era became known as the Medieval era.

During this time warfare was quite limited and battles were brief encounters between forces of several dozen men or several hundred mounted warriors. Swords were the weapons primarily used in the medieval period and a typical battle often consisted of a barrage of arrows being fired and then a person to person combat using swords.( Kodansha Encyclopaedia p246)Castles and defensive fortifications were not the centre of the battle, as they were in Europe at the same time.

A vision of what the mountain castle looked like covered in clouds. What is Japanese Architecture? p97

With the exception of the castles of northern Kyushu, which were built sturdy due to being under constant attack from the Asian mainland, castles at this time were not built as permanent fortifications because of the uneasiness of power. They were small in scale, and often put together at a time of crisis. Stone walls were uncommon. Using the topography, they were built on the top of steep mountain ridges. ( Hinago p246) From on top of the hill, defenders could easily see an enemy approaching and they could use the time that it took for the enemy to climb the hill to set up their defence. Features of the medieval castle are quite difficult to construct as many of the castles of the feudal era were built on top of their ruins.

In the late 14th Century there was a dispute surrounding the Imperial succession and from this time until the national leaders started to appear in the 16th century, fighting within Japan intensified. The Muromachi period (1336-1576) is often referred to as the war years. Warlords started to build stronger more permanent fortifications on mountaintops, similar to their own residences but with towers on the roof. Close to one thousand castles are believed to have been built in Japan during this time.( Kodansha Encyclopaedia p246)

A new era of warfare in Japan, the use of firearms. Rekishikan p601

The castle underwent severe physical changes as well as role changes during this time, due to a change in the style of warfare used in Japan, and due to the growth in power and support of the warlords of the era. By the 1600's, firearms were the most used weapons overriding the usage of spears and bows. Battles changed in style from invantry battles to calvary battles, and the need for a sturdier and stronger fortification arose. From the mid 15th Century warlords also began to grow in power and their desire for power escalated. The warlord that gained enough power had the chance of becoming the shogun, and thus battles raged throughout the Sengoku period (1467 to 1603).( Kodansha Encyclopaedia p246)

In order to protect the large territories that they occupied, the warlord found it necessary to build larger and more complex fortifications. Azuchi-jo (jo meaning 'castle') built by Oda Nobunaga in 1576, was the first of the new generation of castles to be built. From this time on castle building became a national industry in Japan, and construction technology advanced rapidly. Officers known as bugyo or 'commissioners of works' were employed to oversee the building of the castle.( Hinago p90)

Castles began to become closely associated with the commerce and government of the area and mountain sites became inappropriate for this domain. ( Nishi and Hazumi p97) They began to be built on a low plateaus and the hirayama-jo (plain-mountain) type became the standard type of castle being built in the feudal era. The castle now being located on the plain, and facing attack by newly introduced weapons such as firearms, needed extra defensive features that were not necessary for mountain top fortifications.

"Ishiyama katsusen" A sketch of the Edo era. Men firing at their attackers through loopholes. Rekishikan p609

It is at this time that large, strong, stone walls were developed, moats were dug, earthworks added, and new defence and attack features introduced.( Kodansha p248) There was more concentration on the nawabari, of the castle and important castle features such as ishiotoshi, sama and spikes were introduced.

The warlord became the master of his own area, being able to establish and administer his own taxation rates, laws, and even systems of weight and measure.( Nishi and Hazumi p102) Castles were built in the centre of the lords domain, and its function was no longer solely a defensive one. The castle now also contained the residence of the warlord and his personal retainers.

A musket, these were the first firearms introduced to Japan by the Portuegese. Rekishikan p604

People flocked to live in the area surrounding the castle due to the availability of work involved in the building of the castle, and also due to the status surrounding the castle. Towns called jokamachi 'castletowns' started to appear. The construction of castles led to the development of many of the towns which have become the major cities of Japan today. The building of Edo-jo led to the development of Tokyo, the building of Himeji-jo led to the development of the city Himeji and so on.

The well that was built inside of Himeji-jo.(Photo taken from Japanese Castles p128)

The three main warlords which influenced castle building techniques and styles were Oda Nobunaga, Toyotomi Hideyoshi and Ieyasu Tokugawa. It was Hideyoshi who constructed Osaka castle in 1582, in the same year as Azuchi-jo was destroyed. Osaka-jo was one of the most magnificent castles ever constructed. It covered 730,000 square kilometres, and had 5 towers the tallest being 9 stories high. It reputedly required three years of labour by up to 100,000 men. Osaka-jo was unfortunately destroyed in 1615 in a battle with Ieyasu after a month long siege had taken place. Ieyasu took over it and recognising the importance of the location, he rebuilt the castle.( Kirby,J. From Castle to Teahouse p58) The warfare act of siege was introduced, and castles again underwent a slight change with larger storage space and equipment that would help sustain life, such as wells being introduced.

Ieyasu's defeat of Hideyoshi saw him reach national supremacy. In 1603 he became shogun, and started to work for national unity. For the sake of national unity, he issued a law in June, 1615 referred to as the ikkoku ichijo no rei 'one castle per province order'. ( Hinago p47) The government aiming to keep the leaders of the provinces weak and under control to avoid a rebellion. The lords were only allowed to have one castle per province and it had to be the one inwhich they resided. Many castles were demolished. The links with the Feudal era cut. Extensions, repairs to towers, gateways, and walls, as well as any rebuilding of the castles were under rigid prohibitions. Permission from the government was necessary before any maintenance needed could be carried out on the castles. Even rebuilding after fire was strictly controlled. With the achievement of national unity, sense, time and circumstance meant that the castle was no longer needed.