Wednesday, August 23, 2017

Amazaki Castle -First and last island castle-

Amazaki Castle

-First and last island castle-



Name: Amazaki castle (Amazaki-jo)
Place: Imabari city, Ehime
Type: Island Castle
Built: 7th century?
Remaining remnants: Stone walls 

Brief History

Amazaki castle (甘崎城) is built over Kojo island, a small one of about 200 meter long and 50 meter wide near the coast of Omishima island. Omishima island is the largest one among Geiyo islands which spreads between current Hiroshima prefecture and Ehime prefecture, and has been the center of the island both for geographically and functionally.

Omishima island also has been the sacred island in the area. Washigato mountain which is the highest mountain of the island had been an object of faith because of it beautiful shape seen from western coast of the island which was a good anchorage, and also protected ships from strong winds. Oyamazumi Shrine was built to worship this mountain, and this shrine was deeply believed by many lords and generals long time.

Origin of Amazaki castle

The origin of Amazaki castle is unknown but is said that it was built in 7th century, when tension with the peninsula and continent became worse after the fall of Korean Baekje kingdom. Around this time Yamato dynasty built many ancient castles such as Onojo castle, Kii castle or Kinojo castle around north part of Kyushu island and Seto-Naikai sea preparing for foreign invasion, and Amazaki castle might be built as a direct obstacle for foreign fleets as a first island castle of the area.

The name of Amazaki castle had disappeared from the history for hundreds of years, and next emerges as the base of Murakami Navy. Musakami clan is said originally as a local lord of Shinano province (Nagano prefecture), the moved of Seto-Naikai sea area and became a naval lord. Later Murakami clan divided into Innoshima Murakami clan at the north part, Noshima Murakami clan at middle part and Kurushima Murakami clan in the south part.

Reason of island castles

Historically there were many sea clans or navy in the history, but only Murakami clan built island castles as their base. Other sea clans or navy also had fleets but had same importance at lands, thus they built their castles at the mountain near their port. Contrary to this, Noshima Murakami clan used two island castle it mean Amazaki castle and Noshima castle (Ehime prefecture), and Kurushima Murakami clan also lived at Kurushima castle (Ehime prefecture).

As a reason of this fact, Murakami clan had an excellent skill of shipping trained by the swift current of the area, thus they can easily built castles at the island and use them. Additionally, compared with other naval clans, Murakami clan was more independent from land powers. To keep their independence from land powers, island castles surrounded by sea were convenient.

Furthermore, as the main activity and source of income of Murakami navy was escorting ships at the straight for a fee, it was necessary for Murakami clan to find coming ships and respond quickly, both to protect their customers and prevent unpaid passengers. 

To keep their fleet ready, island castles was appropriate to hold their ships directly on the sea. Amazaki castle, Noshima castle and Kurushima castle stand three major straight of the area, and could manage the whole straight cooperatively.

Fall of Murakami navy

Murakami clan became its peak period in the former half of 16th century, but along with the expansion of Mouri clan which became the ruler of Chugoku region and exercised its power to Kono clan, the freedom of Murakami clan gradually limited. Later Murakami clan divided for the response to Hideyoshi Hashiba (1537-1598, later Hideyoshi Toyotomi) who attacked Mouri clan as the commander of central ruler Nobunaga Oda (1534-1582).

In 1588, Hideyoshi Toyotomi who virtually united Japan banned piracy of naval clans. Because of this policy Murakami clan totally lost their incomes, then Kurushima Murakami clan became the lord under Toyotomi government, and Noshima Murakami clan and Innoshima Murakami clan fell into the retainers of Mouri clan. 

After the battle of Sekigahara in 1600, Kurushima Murakami clan transferred to inland Kusu area of Bungo province (Oita prefecture), and the history of Murakami clan as an independent sea clan totally ended at this time. After the move of Mouri clan and Kurushima clan, Geiyo island became the territory of Takatora Todo (1556-1630) who was the lord of Imabari castle (Ehime prefecture).

Renovation by Todo clan

Takatora Todo was an excellent castle builder compared with Kiyomasa Kato (1562-1611), and built many excellent castle not only for himself but also Edo Shogunate. Takatora might have a skill to build stone walls at weak ground. and built seaside or lakeside castles such as Imabari castle, Tsu castle (Mie prefecture) or Zeze castle (Shiga prefecture).

Under the change of the lords of surrounding areas, Takatora had to show the Geiyo island was his territory. In addition to this, as a close lord to Edo Shogunate, Takatora was expected to restrain large lords of Western Japan which might support Toyotomi clan still existed at Osaka castle (Osaka prefecture) by their navy. 

Takatora totally renovated Amazaki castle by stone walls and used as a border castle at straight. Compared with Noshima castle or Kurushima castle, Amazaki castle existed at the center of the straight and could grasp whole straight, and also had less image of Murakami clan than other two castles which were the main bases of Murakami clan.

Structure of Amazaki castle

Most part of structure was lost but the plan of the castle was recorded at the collection of drawings of abolished castles. According to the drawing, the island area is separated into north half and south half by choking point at the middle of the island. North half was the central area of the castle which was about 30 meter long and 15 meter wide, and south half was the secondary area of about 100 meter long and 30 meter wide.

Outside of the island, at the sandy soil which emerges only at ebb tide,. line of stone walls which was 5 meter height might wholly surround the island. Currently only remained at its southeastern edge, but from this remnant it might be a genuine stone wall. The entrance of stone walls were built at its eastern and southern line, the former was the main gate and latter was the back side gate.

Because of limited remnants, it is clear if these outer walls might be built not to expand land or just as a wall. If later it might be intended as a obstacle for approaching ships at high tide, and also as a defense line for landed enemies at ebb tide. Just at the north of southeastern corner, there are many holes drilled at stones, to support wooden sticks to anchor ships.

Afterward of castle

In 1608, Takatora Todo was transferred to Tsu castle by Edo Shogunate. Todo clan still had Imabari castle by 1635, but lost Geiyo islands, thus Amazaki castle might be abolished at this time. Next year Edo Shogunate directly banned large warships for large lords at Western Japan, and Amazaki castle also lost its significance. This was also the end of islands castle at this area. Later German doctor who sailed near the ruin of the castle in 1691 recorded projecting stone wall from the water.

Because of the destruction and swift current, most remnant of the castle was lost. But remaining southeastern corner and liner base line stones at southwestern part still keep unique atmosphere of the castle. Today under quite limited condition of strong ebb tide once or twice per year the castle island is connected to Omishima island, and only this time sunken castle shows its shape to the people.


No detailed information for safety.

Related Castles

Noshima Castle -Ship like castle of sea clan lived at swift tide-
Kurushima Castle -Island base of sea clan protected by swift current-
Imabari Castle -Water castle in town of marine transportation-
Tsu Castle -People who does not change his master seven times is not full fledged-

Pictures (click to enlarge)

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