Japan Castle Explorer: September 2016

Mitsuishi Castle

-Castle at various borders-

Overview

Name: Mitsuishi castle (Mitsuishi-jo)
Alias:
Place: Mitsuishi Bizen city, Okayama
Type: Mountain Castle
Built: 1333
Remaining remnants: Stone walls, clay walls and moats
Title:

Brief History

Mitsuishi castle (三石城) is built on Shiroyama mountain, one of about 200 meter height from hillside at the meeting point of Kongo-gawa river, a large tributary of Yoshii-gawa river and its tributary Funasaka-gawa river.

Castle place is only four kilometer away Funasaka-Toge pass of Sanyodo road, which separated Bizen province (eastern part of Okayama prefecture) and Harima province (south part of Hyogo prefecture).

Sanyodo Road, one of the major roads of Japan which connected Kyoto city and Hakata port since ancient era, ran different routes at each period but constantly passed Funasaka Toge pass because of its geographical condition.

Today newer transportation methods such as Chugoku Jidoshado highway or Sanyo Shinkansen line run straightly across Hosaka Toge pass at the south, but even now local artery including Route 2 and Sanyo-Honsen line still runs over Funasaka-Toge pass. Because of its location, Mitsuishi castle was an important defense point at the border.

Origin of Mitsuishi castle

According to Taiheiki, a military tale treats the fall of Kamakura Shogunate, confrontation between South Court and North Court and establishment of Muromachi Shogunate in the former half of 14th century, Mitsuishi castle was built by local lord Nobuhiro Ito (?-?) in 1333. At that year, responding of anti Kamakura Shogunate order by Emperor Godaigo (1288-1339), Norimura Akamatsu (1277-1350, famous for his Buddhist name Enshin Akamatsu) who was the local lord of Harima province raised his army against Shogunate.

Kamakura Shogunate ordered retainers at Bizen province including Nobuhiro Ito to attack Akamatsu army from backside, but Norimura Akamatsu intercepted this attack at Funasaka-Toge pass and beat them. As Nobuhiro surrendered to Akamatsu army, Norimura let Nobuhiro to build Mitsuishi castle to secure his backward, and marched toward Rokuhara Tandai, an administrative office of Shogunate at Kyoto city.

Norimura merged with Takauji Ashikaga (1305-1358) who was sent from Kamakura Shogunate as a commander but turned to Emperor Godaigo side and fell ruined Rokuhara Tandai. Hearing that news Yoshisada Nitta (1300-1338), another large local lord at Kanto region who already raised anti-Shogunate army, attacked Kamakura city and finally ruined Kamakura Shogunate.

Royal retainer supported Muromachi Shogunate

But after the fall of Kamakura Shogunate, Emperor Godaigo who tried to administer directly could not well coordinate of interest between retainers. Looking at this, Takauji Ashikaga who was sent to subjugate the revolt by remnants of Kamakura Shogunate left Emperor and built his own government. Takauji once marched to Kyoto city and captured it, but was defeated by Emperor side army led by Yoshisada Nitta and Akiie Kitabatake (1318-1338). Takauji escaped to Kyushu island and seek for chance.

As Norimura supported Takauji, next Nitta army attacked the territory of Akamatsu clan. Enshin built Shirohata castle at about 5 kilometer northwest from Kanjosan castle, and built many branch castles including Kanjosan castle at surrounding mountains as front forts. Being overwhelmed by Emperor side army, Enshin and his sons tenaciously resisted and kept Shirohata castle over 60 days.

Among this time gained by Akamatsu clan, Takauji formed large army at Kyushu island and beat Emperor side army at the battle of Tatarahama, then marched to Kyoto city again. Finally Takauji broke Emperor side army at the battle of Minatogawa, thus Emperor Godaigo left Kyoto city and moved to Yoshino region and opened Southern Court there.

Temporal fall of Akamatsu clan

Under Muromachi Shogunate established by Takauji, because of their contribution, Akamatsu clan became one of the highest class retainers along with distinguished Samurai families. Akamatsu clan held provinces at Sanyo region such as Harima province, Bizen province and Mimasaka province (north part of Okayama prefecture)as the governor and prospered, but later was became to be watched by Shogunate.

Akamatsu clan appointed Uragami clan as a deputy governor of Bizen province. Uragami clan was originally a small local lord of Harima province, but activated at many battles with South Court army then promoted to the deputy governor. As a rear guard of Akamatsu clan and window to Bizen province, Uragami clan resided at Mitsuishi castle.

In 1441, Mitsusuke Akamatsu (1381-1441), the leader of Akamatsu clan, assassinated sixth Shogun Yoshinori Ashikaga (1394-1441) who tried to monopolize and decrease the power of Akamatsu clan. Akamatsu family besiege at their main base Shirohata castle but was subjugated by Shogunate as a traitor and once ruined.

Uplift of Uragami clan

But after that people of Akamatsu clan contributed to Shogunate several times then Akamatsu clan revived as the governor of Harima province (southern part of Hyogo prefecture) and Bizen province (eastern part of Okayama prefecture). After the battle of Onin, Akamatsu clan strengthened its domination to the territory under Masanori Akamatsu (1455-1496) and changed to warlord.

However, after the death of Masanori Akamatsu, Akamatsu clan fell into a period of disorder. Norimune Uragami (1429-1502) worked for the revival of Akamatsu clan and was appointed as the deputy governor of Bizen province, but was later watched from Uragami clan then became opposed.

In 1519, Yoshimura Akamatsu (?-1521), son of Masanori, attacked Muramune Uragami (?-1531), the leader of Uragami clan at Mitsuishi clan at Mitsuishi castle, to retrieve the authority. But Muramune rejected this attack by the assist of Yoshiie Ukita (?-1534), the grandfather of Naoie Ukita (1529-1582) who later ruined Uragami clan. Around this time, Mitsuishi castle might be transformed into modern castle with stone walls, to enhance defense ability and shot the authority of Uragami clan.

Structure of Mitsuishi castle

Mitsuishi castle spreads a crescent moon like curved ridge of Shiroyama mountain. Central area of the castle is a oblong shaped terrace of 50 meter long and 30 meter wide, which has a low basement of main building with stone walls. Clay wall surrounds western half of this circle, where faces route from outside.

Secondary area is a small square shaped area at the south of central area, which is same to Umadashi buffer area at later castle. Third area is a narrow and long area of about 100 meter long and 20 meter wide, which has basement of buildings and two ruins of well. At the edge of this third area, there is a small basement of guarding turret, equips small stone walls and protected short cut route from hillside..

Main gate of the castle is built at the small valley from core areas, with folded stone walls forms small buffer area. From west to north of central area, dry moat which also used as a path roundly continues. Outer wall of this dry moat is partially protected by stone walls, at north side of central area which is connected to the backside gate.

Ahead of this dry moat, outer area which is about 50 meter long and 20 meter wide is built to protect backside of the castle. This area is securely guarded by clay wall, and dry moat at its northern edge. Total size of the castle is about 300 meter long and 100 meter wide, and round shaped area keeps original shape of the castle but also combines modern elements such as stone walls and buffer areas. Mitsuishi castle was also at the border of medieval castle and modern castle.

Struggle against former master

Muramune rejected the attack of Akamatsu clan now surpassed their master and seized his own authority. Muramune forced Yoshimura Akamatsu to retire and leave the leader position to his son Harumasa Akamatsu (1513-1565), and finally assassinated him in 1531. Muramune used Harumasa as a puppet and seized the power of Akamatsu clan, next participated in the internal conflict of Hosokawa clan, which seized the authority of Kyoto city.

Muramune belonged to Takakuni Hosokawa (1494-1531) and participated in the battle of Daimotsu-Kuzure as a main body of Takakuni Hosokawa army, but because of the invitation of Motonaga Miyoshi (1501-1532), the enemy of Takakuni, Harumasa Akamatsu suddenly betrayed Muramune at the battlefield to make a revenge of his father and attacked from backside. Hosokawa army including Muramune collapsed, and Muramune died in the battle.

In addition to the death of the leader, Amago clan which was the strong warlord of Izumo province (Shimane prefecture) intruded into the territory of Uragami clan. Masamune Uragami (1520-1564), son of Muramune, once ran away from Bizen province with Harumasa Akamatsu, but later returned to his territory at the temporal retreat of Amago clan in 1542.

Ahead of the borders

But Amago clan invaded into Bizen province again in 1551. Facing this threat, Uragami clan divided into Masamune Uragami who subordinated to Amago clan, and his younger brother Munekage Uragami (?-?) still fought against Amago clan under the support of Mouri clan, the warlord of Aki province (Hiroshima prefecture) and the rival of Amago clan.

Along with the downfall of Amago clan, Munekage recovered his territory from Amago clan and advanced into the warlord. Around this time Munekage newly built Tenjinyama castle (Okayama prefecture) as his new main base at higher mountain near the center of Bizen province and moved from Mitsuishi castle.

By leaving Mitsuishi castle and building Tenjinyama castle, Uragami clan finally left the position of deputy governor and evolved into true warlord. Uragami clan itself was at the border at Mitsuishi castle. The geographical importance of Mitsuishi castle was unchanged. but eastern border of Uragami clan and Ukita clan which beat Uragami clan was Kanjosan castle (Hyogo prefecture) at far eastern area in Harima province, thus Mitsuishi castle was not used any more.

Afterward of castle

Today no building is left but structure of the castle well remain on the mountain. Its halfway size and combine of medieval and modern element at the edge of province well shows a delicate position of Uragami clan as a deputy governor under Akamatsu clan. Compared with Mitsuishi castle, majestic shape of their next base Tenjinyama castle clearly shows unconstrained situation of Uragami clan which overcame Akamatsu clan and evolved into true warlord.

Access

10 minutes walk from JR West Sanyo-Honsen sen line Mitsuishi station to hillside entrance at Mitsuishi Myojinsha shrine. 40 minutes walk from hillside to hilltop castle. 20 minutes drive from Sanyo-Jidoshado Expressway Bizen interchange at parking at backside ahead of Mitani-no-Taki fall. 30 minutes walk from parking to hilltop castle.