INTERACTIVE BATTLE
The Suō–Nagato Campaign and the Fall of the Ōuchi
1 May 1557 · Katsuyama Castle and Chōfuku-ji in Nagato Province (now Chōfu, Shimonoseki)
After the victory at Itsukushima, Mōri Motonari invaded Suō and Nagato, took Yamaguchi and drove Ōuchi Yoshinaga into Nagato. Yoshinaga took his own life at Chōfuku-ji and the Ōuchi house came to an end.
Background
With Sue Harukata gone, the Ōuchi had no strength left to hold Suō and Nagato. Motonari crossed into Suō soon after his victory, reduced strongholds such as Susuma-numa Castle and closed on Yamaguchi.
Outcome
Yoshinaga took his own life at Chōfuku-ji, and Suō and Nagato passed to the Mōri. The Ōuchi house was extinguished, and Mōri territory spread far westward from Aki and Bingo.
Course of the battle
1 October 1555 – February 1557
The Mōri reduce the strongholds of Suō
From soon after the victory at Itsukushima the Mōri crossed into Suō and attacked the Ōuchi castles. Strongholds such as Susuma-numa fell, opening the road to Yamaguchi.
Invades Suō
Sources23·Certainty: Medium
2 March 1557
Yoshinaga leaves Yamaguchi for Nagato
As the Mōri closed on Yamaguchi, Ōuchi Yoshinaga left the city and its castle of Takamine and moved with his senior retainer Naitō Takayo to Katsuyama Castle in Nagato.
Leaves Yamaguchi
Accompanies Yoshinaga
Sources13·Certainty: Medium
3 March – April 1557
Katsuyama Castle is besieged
Yoshinaga and Naitō Takayo held Katsuyama Castle, which by the account of Yamaguchi Prefecture was a strong mountain fortress and gave the Mōri trouble. The Mōri also closed the sea and tightened the ring.
Points of debate
One tradition has Naitō Takayo surrendering the castle on condition that Yoshinaga's life be spared; accounts of how Yoshinaga then came to be pressed to kill himself differ.
Holds Katsuyama Castle
Presses the pursuit in Nagato
Sources13·Certainty: Medium
4 1 May 1557
Ōuchi Yoshinaga takes his own life at Chōfuku-ji
As the castle was about to fall, Yoshinaga moved to Chōfuku-ji, the temple known today as Kōzan-ji, and there took his own life. With him the Ōuchi, the greatest house in western Japan, came to an end.
Takes his own life at Chōfuku-ji
Sources14·Certainty: High
Historical significance
The Ōuchi, the greatest house in western Japan, disappeared, and their lands and its window on overseas trade passed to the Mōri. Across the Kanmon Strait, Mōri and Ōtomo now faced each other over Buzen and Chikuzen.
Key figures
毛利氏
3
Commander of the Mōri army
He took the main body against Yamaguchi and left the pursuit in Nagato to his retainers.
Sources2·Certainty: Medium
Head of the main Mōri house
He took part with his father in the reduction of Suō and Nagato.
Sources2·Certainty: Medium
Commanded the advance into Nagato
He led the pursuit of Ōuchi Yoshinaga in Nagato and is said to have surrounded Chōfuku-ji.
Sources2·Certainty: Medium
大内氏
2
Last head of the Ōuchi house
Raised to the headship by Sue Harukata. He left Yamaguchi, held Katsuyama Castle and took his own life at Chōfuku-ji.
Sources1·Certainty: High
Senior retainer of the Ōuchi
He followed Yoshinaga into Katsuyama Castle and fought the Mōri there.
Sources1·Certainty: Medium
Other events of 1557
Notes on the data
Dates are given in the Western (Julian) calendar. The sources use the lunar calendar; 1 May corresponds to the third day of the fourth month of Kōji 3. Katsuyama Castle in Nagato is also written Katsuyama with different characters; the form used here follows the castle master data. Chōfuku-ji is the temple known today as Kōzan-ji in Chōfu, Shimonoseki.
Sources consulted
- 山口県「さらば!! 西国一の大名・大内氏「最後の当主」大内義長」
- Wikipedia「防長経略」
- 城郭マスタ（shiro.geojson）
- 地理院地図 住所検索（山口県下関市長府川端1-2-3）
The numbers in the text refer to the list above. Certainty indicates how far a statement is supported by the cited sources; it does not refer to the precision of the coordinates or the dating.
Advertisement