Noshima Castle: A Sengoku Maritime Fortress in Japan
Site at a Glance
- Rating
- 4.8
- Popularity
- Very Low
- Country
- Japan
- Primary era
- Medieval
- External website
- Open
- Eras represented
- Medieval
- Civilizations
- Japanese
- Site type
- Military
- Remains
- Castle
On this page12 sections
History
Noshima Castle is a Japanese castle from the Sengoku period, the era of civil warfare from the fifteenth to the late sixteenth century, on Noshima Island near Imabari in Japan. Traditionally attributed to Murakami Yoshihiro, it is generally dated to the Nanboku-cho period and occupied an important maritime position in the Seto Inland Sea. The castle guarded a narrow passage through the Geiyo Islands, where control of shipping and naval movement carried both military and economic value.
Origins of the Noshima Murakami
The exact beginnings of the Noshima Murakami base remain uncertain. A genealogical tradition connects the family to Kitabatake Chikafusa, a fourteenth-century court noble and historian associated with the Southern Court, and states that a descendant established power in the Inland Sea before inheriting the influence of Murakami Yoshihiro. The Murakami tradition later divided into the Noshima, Innoshima, and Kurushima branches. Another record does not identify the castle’s builder.
The islands around Noshima formed a crossing between Shikoku and Honshu and provided anchorages during storms. Their reefs, shoals, narrow channels, whirlpools, and powerful currents supported maritime communities involved in transport, commerce, navigation, and the collection of passage tolls. In wartime, these communities supplied mercenary naval forces and sometimes engaged in piracy. The Murakami maritime clans therefore combined commercial and military activities within a landscape shaped by the sea.
Muromachi-period alliances
During the Muromachi period, the age of the Ashikaga military government, the Murakami divided into three principal houses. The Kurushima branch was associated with Shikoku and owed allegiance to the Kono clan, the military governors of Iyo Province. The Innoshima branch was connected to the Mori clan around Onomichi. The Noshima branch maintained a neutral position and cultivated direct relations with the Muromachi shogunate, Japan’s central military government under the Ashikaga family.
In 1499, Ashikaga Yoshitane took refuge at Noshima Castle after the Hosokawa clan expelled him from Kyoto following an attempted coup. While Yoshitane traveled to Suo Province to seek support from the Ouchi clan, Murakami Masafusa provided naval assistance and rebuilt the castle as a base for the counterattack against the Hosokawa.
Naval warfare and the end of independence
The Noshima Murakami supported the Mori clan at the Battle of Miyajima in 1555. In 1576, during the Battles of Kizugawaguchi, their naval forces defeated the Kuki navy, which was allied with Oda Nobunaga. Two years later, the balance changed when Nobunaga deployed six ships protected by armored plates, and the Murakami forces were defeated.
Toyotomi Hideyoshi initially tried to bring the Murakami into his alliance during his campaign against the Mori. The Kurushima branch defected to Hideyoshi, but the Noshima branch remained loyal to the Mori. After Hideyoshi’s victory, his 1588 order prohibiting piracy sought to suppress independent armed maritime groups involved in piracy and naval warfare. In the same year, he deprived the Noshima Murakami of their castle and forced them to leave for Mori territory. Noshima Castle was consequently abandoned.
Abandonment and preservation
Noshima became uninhabited from the Edo period onward, helping preserve the castle remains. The ruins were designated a National Historic Site of Japan in 1953. The Ehime Prefectural Board of Education established the Noshima Maritime Clan Village facility in 1973, and investigations of the cultural remains continued periodically. In 2017, the site was selected as number 178 in the Continued Top 100 Japanese Castles.
Cherry trees were planted on Noshima in 1931. Landslides and bedrock collapses followed the 2018 Western Japan floods and a typhoon approach in 2019, with tree roots considered one contributing cause. In 2022, most of the trees, including the Somei Yoshino cherries, were cut down and their roots removed to reduce the risk of damage to archaeological remains and artifacts.
Remains
Noshima Castle occupied the whole of Noshima Island, an approximately 1.5043-square-kilometre island in the Miyakubo Strait. The surrounding tidal currents and whirlpools formed part of its natural defense, while the castle’s built defenses followed the island’s central ridges. The surface was flattened into three terraces, and three ridges extending from the centre were enclosed by stone walls to create separate defensive areas. The principal enclosures were the main bailey, second bailey, third bailey, and outworks.
Island defenses and maritime facilities
Terraces and enclosures
The three terraces organized the fortified island into connected but distinct areas. Stone walls enclosed the ridges and formed the main bailey, second bailey, third bailey, and outworks. During wartime, Noshima functioned primarily as an inner bailey, or fortified central area. The Noshima Murakami residence stood on neighboring Hakatajima, while shipyards and warehouses occupied Ujima. Watchtowers on several smaller islands extended the surrounding maritime defense system.
Boat basin
A relatively sheltered anchorage called the boat basin occupied the north shore, where the currents were weaker. It served the castle’s naval function within an otherwise strongly tidal setting. Noshima had no reliable water source, so water was reportedly brought from nearby Ujima and Koura.
Taisaki-jima outwork
Historical maps show a bridge linking Noshima with Taisaki-jima. The associated island is an elongated, level piece of ground measuring approximately 22 metres from east to west and 50 metres from north to south. Its form and position have led to its interpretation as an outwork or lookout position belonging to Noshima Castle.
Reef post holes
Showa-period surveys identified 340 post holes in the reefs around Noshima. They are interpreted as supports for piers used to moor warships. A further 120 post holes were found in the reefs of Taisaki-jima. Together, these remains indicate the scale of the castle’s naval infrastructure and place Noshima among the largest maritime fortifications in the Seto Inland Sea.
Present condition
Noshima’s abandonment and continued uninhabited state helped preserve its castle remains. The removal of most trees and their roots in 2022 addressed the danger posed by slope failure and rock collapse, protecting the archaeological remains and artifacts within the island fortress.
