Battle of Gassan Toda-jo Castle (月山富田城の戦い)

The Battle of Gassan Toda-jo Castle was a battle that occurred from 1542 to 1543 and from 1565 to 1566 over Gassan Toda-jo Castle located in Izumo Province (present-day Yasugi City, Shimane Prefecture) which was the base of the Amago clan. This battle consisted of two parts: the First Battle of Gassan Toda-jo Castle and the Second Battle of Gassan Toda-jo Castle. The first battle was a fight between the Ouchi and Mori allied forces and the Amago clan. After the fall of the Ouchi clan, Motonari MORI started the second battle and destroyed the Amago clan.

The First Battle of Gassan Toda-jo Castle

In 1541, the Amago army under the command of Haruhisa AMAGO attacked Yoshida Koriyama-jo Castle, the base of the Mori clan, with 30,000 men; however, he was repelled by the 3,000 strong Mori army with reinforcements from the Ouchi clan (See Siege of Koriyama)

Following Tsunehisa AMAGO's death after the Amago clan failed in the invasion of Aki Province, the Ouchi and Mori armies departed for Izumo Province on February 5, 1542. For the Ouchi army, Yoshitaka Ouchi himself became supreme commander and went into battle with an army of 15,000 men including Takafusa SUE, Shigenori SUGI, Okimori NAITO, and Takakane HIRONAKA. For the Mori army, Motonari MORI, Masahira KOBAYAKAWA, and Fujikane MASUDA departed for Izumo Province recruiting local samurai from Aki, Suo, and Iwami Provinces.

In May, they advanced into Izumo Province; however, as it took three long months to capture Akana-jo Castle they set up their headquarters in Mitoyamine in November. Soon after the New Year they relocated their headquarters to Mount Kyoragi, which overlooked Gassan Toda-jo Castle. In April battle commenced, but they encountered guerrilla attacks from the Amago army and suffered from a shortage of military supplies. Furthermore, allies of the Ouchi army, such as Hisasuke MITOYA, Tamekiyo MISAWA, Tsunemitsu HONJO, and Okitsune KIKKAWA took Amago's side, so the Ouchi forces became inferior in strength. The Ouchi forces began to withdraw on June 19, 1543, and returned to Yamaguchi City on July 7.

After this one year and four month long invasion ended in failure with Yoshitaka losing his adopted son Harumochi OUCHI, Yoshitaka completely lost his political ambition. This battle became a factor in the decline of the Ouchi clan; the Amago clan, on the other hand, regained its power under Haruhisa and entered a golden age. After the fall of the Ouchi clan, the Mori clan continued to have a devastating conflict with the Amago clan over Iwami Province.

Battle of Shiraga-jo Castle

After the fall of the Ouchi clan in 1562, Motonari invaded Izumo Province with an army of 20,000 men, including his son Motoharu KIKKAWA and Takakage KOBAYAKAWA. On the Amago side Haruhisa died in the previous year and was succeeded by his son Yoshihisa AMAGO.

First, the Mori forces attacked Shiraga-jo Castle, one of the "Amago Jikki" (ten subsidiary castles to protect the main Amago castle, Gassan Toda-jo Castle). Shiraga-jo Castle was protected by an army of 2,000 men under the command of Mitsuhisa MATSUDA and Hisakiyo USHIO. Shiraga-jo Castle functioned as a gateway to the Japan Sea side of the Gassan Toda-jo Castle. The Mori forces noticed that if this castle surrendered, the Amago forces could not transport the supply of provisions from the Japan Sea by boat, and Gassan Toda-jo Castle would be helpless.

During the battle, Takamoto MORI died suddenly in 1563. Motonari tried to conceal his grief and talked to his soldiers, saying, "The only thing for the repose of Takamoto's soul is to destroy the Amago clan," and the morale of the whole army soared. Motonari employed coalminers of Iwami silver mine to make a tunnel for the purpose of capturing a water well of Shiraga-jo Castle and cutting off the water supply. The Amago side sent an army of 10,000 men including Yoshihisa's brother Tomohisa AMAGO to the relief of Shiraga-jo Castle; however it was not successful and the castle fell in October. In November, the Mori army occupied a position near Gassan Toda-jo Castle to engage in a war of attrition.

The Second Battle of Gassan Toda-jo Castle

After the conquest of Shiraga-jo Castle, Motonari MORI gained control of the Amago clan's military bases one by one; in 1565, his forces besieged Gassan Toda-jo Castle and cut off the supply route so as to starve the enemy. In April the same year, the Mori army attacked Gassan Toda-jo Castle from three sides, but was defeated, and finally withdrew.

In September the Mori army besieged Gassan Toda-jo Castle once more, and engaged in a war of attrition. The siege lasted until the following year. The Mori forces did not accept an offer of surrender from castle defenders at first. It was envisaged that many soldiers would be holed up in the isolated castle, and their provisions would run out without fresh supplies. Seeing their provisions begin to run out, the Mori side accepted the offer of surrender, and dozens of the besieged soldiers formed a group and surrendered.

Meanwhile, the Amago side continued the battle by secretly carrying provisions Hisakane UYAMA had bought with his own money into Gassan Toda-jo Castle from a side road. However, following an incident when Yoshihisa AMAGO killed Hisakane UYAMA after believing he had been slandered the army's spirits were gradually weakened. The Amago clan surrendered on January 11, 1567. The Mori side guaranteed the lives of the Amago family including Yoshihisa AMAGO, but Yoshihisa and others were taken away to Aki Province and were placed under confinement. In addition, this was the first battle in which Terumoto MORI and Motonaga KIKKAWA participated.

Postwar repercussions

One man was discontented with the fact that the Amago army surrendered. It was Yukimori YAMANAKA, also known as Shikanosuke YAMANAKA.

Yukimori worked hard for the restoration of the Amago clan with his uncle Hisatsuna TACHIHARA. First, in 1568, they made Katsuhisa AMAGO, a grandson of Kunihisa AMAGO and a priest, quit the priesthood, and installed him as the head of the family. Then they recruited former retainers of the Amago clan and invaded Tajima Province. They took part in various battles held in Izumo and Inaba Province, and even joined the army of the Yamana clan with the aim of restoring the Amago clan firmly in mind. They excelled militarily and defeated Takanobu TAKEDA, who rebelled against the Yamana clan and became holed up in Tottori-jo Castle.

After leaving the Yamana clan, Katsuhisa Amago and his party succeeded in recovering most of the occupied territory in Izumo Province, and they temporarily gained a foothold toward the restoration of the Amago clan. After the levy of troops in 1569, they attacked Gassan Toda-jo Castle which was protected by Takashige AMANO on Mori's side and attempted to drive the Mori clan out of Izumo Province. However, Gassan Toda-jo Castle was so strongly fortified that they abandoned their attempt. Moreover, Yukimori, who had been defeated in the Battle of Fubeyama, was captured by Motoharu KIKKAWA in 1571. However, Yukimori, who had been detained, pretended to contract dysentery and remained in the lavatory; seizing an opportunity, he reportedly escaped through the lavatory smeared with feces. He fled to Kyoto again with Katsuhisa to ask Nobunaga ODA for help.

In 1577, when Hideyoshi TOYOTOMI advanced to Himeji-jo Castle in Harima Province to carry out the Oda army's strategy for subjugating the Chugoku district, Yukimori and his party entered Kozuki-jo Castle located to the west of Himeji-jo Castle. They fought in the front line of the battle against the Mori clan without regard for their lives in the hope of restoring the Amago clan.

However, Nagaharu BESSHO raised a rebellion in the eastern part of Harima Province. As this rebellion had repercussions in various regions in Harima Province, Hideyoshi had to attack Miki-jo Castle occupied by the Bessho clan before he could turn his attention to anything else (the Battle of Miki).

The Amago army in Kozuki-jo Castle, which had been besieged by the massive forces of the Mori clan, became isolated and helpless because they lost any remaining hope of Hideyoshi's support. In the end, the lives of castle defenders were spared in exchange for the suicide of the Amago family including Katsuhisa, and Kozuki-jo Castle surrendered (the Battle of Kozuki-jo Castle).

Yukimori was captured again; however, his dramatic escape was so firmly entrenched in the enemy's mind that he was killed while being escorted to prison.

The death of Yukimori, who had continuously bothered the Mori clan, brought an end to the armed movement for the restoration of the Amago clan.