Siege of Iwamura Castle


Oda Clan

Mino Province

Takeda Clan

Date:  Genki 3 (1572) to Tenshō 3 (1575)

Location: Iwamura Castle in the Ena District of eastern Mino Province

Outcome:  After the Oda severed supply lines to Iwamura Castle, the defenders including Akiyama Torashige, members of the Tōyama family, and other supporters of the Takeda surrendered.

Commanders:  Oda Nobunaga, Oda Nobutada, Kawajiri Hidetaka, Mōri Hideyori

Forces:  60,000 (?)

Casualties:  Unknown

Commanders:  Takeda Katsuyori, Akiyama Torashige, Yamagata Masakage, Baba Nobuhara

Forces:  20,000 (?)

Casualties:  All defenders in the castle burned

The Siege of Iwamura Castle occurred from 1572 to 1575 in the Ena District of Mino Province.  The conflict was waged between the Takeda clan and the Oda clan over control of Iwamura Castle.


Oda expedition in 1572

On 8/14 of 1572, Tōyama Kagetō, the lord of Iwamura Castle who wielded power in eastern Mino on behalf of the Iwamura-Tōyama clan died of illness without children.  Oda Nobunaga dispatched Oda Nobuhiro and Kawajiri Hidetaka along with others to occupy Iwamura, and positioned his fifth son, Gobōmaru (Oda Katsunaga) to be adopted by the Tōyama clan.  At the time, Gobōmaru was still an infant so Nobunaga’s aunt, Otsuya-no-kata (Kagetō’s widow), served as the actual lord of the castle.

Takeda expedition in 1572

On 10/3 of 1572, Takeda Shingen launched the Western Campaign (seijō-sakusen) after broadly announcing to assorted powers that he would march upon the capital of Kyōto.  In the twelfth month of 1572, Akiyama Torashige led the Takeda army to attack Iwamura Castle, the primary base for the Tōyama clan of eastern Mino.  The Tōyama had previously served the Takeda clan, but, around this time, Nobunaga’s aunt, Otsuya-no-kata, was serving as the lord of Iwamura Castle and had an antagonistic relationship with the Takeda.  The Iwamura-Tōyama clan faced a crisis after the Takeda (Akiyama) laid siege to the castle so Otsuya-no-kata surrendered on the condition that she would wed Akiyama Torashige.  The surviving members of the Iwamura-Tōyama clan who lived through the Battle of Kamimura (in the twelfth month of 1570) and their families came under the command of the Takeda.  On 11/14, Iwamura Castle came into the hands of the Takeda, and Shimjō Nobuuji entered the castle.  In a letter dated 11/15 from Nobunaga to Nobetomo Sado-no-kami (Nobumitsu), he said that the situation at Iwamura was inevitable and, in recognition for his efforts, awarded him the neighborhoods of Hiyoshi and Kamado in the Toki District of Mino.

Near Iwamura Castle stood the Daien Temple affiliated with the Myōshin Temple faction of the Rinzai sect of Buddhism that served as the family temple for the Tōyama clan.  As one of the most significant temples in eastern Mino, the site covered approximately fifteen hectares and regularly had 100 resident monks.  Kian Genmitsu, the chief priest of the temple, had earlier served five times as the chief abbot at the Myōshin Temple in Kyōto, as well as the chief priest of the Eirin Temple in Kai Province.  Genmitsu was a well-known priest and old acquaintance of Takeda Shingen.  Shingen asked Genmitsu to return to the Eirin Temple on multiple occasions, but Genmitsu firmly refused. Owing to his resentment at being refused, Shingen ordered the Daien Temple to be burned down and Genmitsu to be killed.  On 11/26 of 1572, approximately two weeks after the opening of Iwamura Castle, the Daien Temple was burned down in the course of battle by the Takeda (Akiyama) army.  Lost in the blaze were the temple structures, along with invaluable cultural assets including Buddhist statues, gardens, multi-generational graves for the Tōyama clan, family registers, documents, and pictures.    

Genmitsu fled from his associates and the temple.  Upon hearing this news, Akiyama sent three assassins after him.  The assassins caught up to Genmitsu and his fellow travelers and killed them all on a bridge over the Iibama River.  However, within less than half a month thereafter, the three became crazy, fell from disoriented horses and lost their lives.  Moreover, five months later, Shingen himself died.  According to one theory, Shingen had Genmitsu killed to silence him owing to Genmitsu’s awareness of Shingen’s serious illness.  Genmitsu and the other victims were buried nearby by villagers.  On 12/22 of 1572, the Battle of Mikata-ga-hara occurred.

Takeda expedition in 1573

At the end of the second month of 1573, Otsuya-no-kata, through the offices of Oda Kamon (Tadahiro), held a wedding ceremony with Akiyama Torashige and Gobōmaru was sent to Kōfu in Kai Province.

On 3/6, Takeda Shingen received news that Nobunaga had deployed to eastern Mino so he ordered Torashige to deploy to Mino.  On 3/15, after 800 soldiers led by Baba Nobuharu who were attacking Iwamura Castle turned to attack the Oda army, Nobunaga pulled back 10,000 soldiers.  Takeda forces including 30 mounted soldiers from Etchū, 30 mounted soldiers from Hida, and 50 mounted soldiers under Okabe Masatsuna gave chase, killing 27 foot soldiers.  Next, Iwamura Castle fell and local fighters from Iwamura surrendered, enabling Akiyama Torashige to enter the castle again.  On 4/12 of 1573, Takeda Shingen died of illness en route to Kyōto and was succeeded by his fourth son, Takeda Katsuyori.

Battle in 1574

On 1/27 of 1574, in a bid to apply pressure on Nobunaga, Takeda Katsuyori marched to Iwamura Castle and surrounded Akechi Castle.  At the Battle of Akechi Castle on 2/5, Nobunaga deployed with his eldest son, Oda Nobutada, but prior to their arrival, on 2/6, Akechi Castle had fallen after a betrayal at the castle by Iibama Uemon-no-jō so Nobunaga positioned Kawajiri Hidetaka at Tsuruga Castle and Ikeda Tsuneoki at Ori Castle, and, on 2/24, retreated to Gifu.  At this time, Nobunaga was said to have led 60,000 men, but as Yamagata Masakage led 6,000 soldiers on a march toward Mount Tsuruoka, Nobunaga pulled back his forces.

Oda expedition in 1575 and surrender

On 5/21 of 1575, Takeda Katsuyori incurred a major defeat to the allied forces of Oda Nobunaga and Tokugawa Ieyasu.  At the Battle of Nagashino, Katsuyori lost many senior retainers including Yamagata Masakage and Baba Nobuharu.  As a result, the Oda and Tokugawa forces began a counteroffensive against the Takeda.  Nobunaga assigned an army to Nobutada to attack Iwamura Castle.  Katsuyori attempted to respond with reinforcements, and after hearing of these movements, on 11/14, Nobunaga headed from Kyōto to Gifu. Family members of the Akechi-Tōyama and Naegi-Tōyama clans who survived the Battle of Kamimura and opposed the Takeda (Akiyama) army sided with the allied forces of the Oda and Tokugawa.  Over the prior half year, forces were stationed included Tōyama Saemon in Nakatsugawa, Nobutomo Nobumitsu (Toki Sanpei) at Takeori,  Ori Naisa at Ōgawa, and Tōyama Yonosuke at Kamimura, severing supply lines to Iwamura Castle from all directions. 

The siege caused starvation among those in Iwamura Castle.  In an effort to escape from these circumstances, on 11/10, supporters of the Takeda and Tōyama holed up in the castle attempted to resist including a nighttime attack against the Oda position nearby on Mount Suishō, but were subject to counterattack by Kawajiri Takahide, Mōri Hidetaka, Asano Sakon, and Saruogi Jintarō.  Members of the Tōyama family and those aligned with the Takeda including Tōyama Gorō-Tomonaga, Sawanaka Sachūta-Mitsutoshi, Iizuma Shingorō, and Kosugi Kanbei were killed in action.  Altogether, the defenders lost twenty-one commanders and 1,000 out of a total of 3,000 soldiers from the castle, dwindling their zeal to fight.  Facing precarious circumstances, Akiyama Torashige sent Tsukamoto Kotaizen as a messenger to offer surrender to Nobunaga and the Oda accepted.

Post-siege actions

Nevertheless, Nobunaga despised Akiyama Torashige owing to Torashige’s earlier actions capturing Iwayama Castle and taking Nobunaga’s aunt, Otsuya-no-kata, as his wife, so, on 11/21, when Torashige and other generals in his party including Ōshima Mokunosuke and Zakōji Tamekiyo came for a ceremonial pardon, he apprehended and took them to Gifu.  Meanwhile, Otsuya-no-kata was crucified upside down at Kawahara along the Nagara River near Gifu Castle.  This served as retribution for the earlier crucifixion by Takeda Katsuyori of the wife of Okudaira Nobumasa of Nagashino Castle after Nobumasa betrayed the Takeda in favor of Tokugawa Ieyasu.  Other members of the Tōyama clan holed up in the castle who supported the Takeda, including Umaki Jūnai, Umasaka Kyūma, Subuchi Denzaemon, Kubohara Takumi, and Ōbune Gorokuta died in battle, while Tōyama Jirō-saburō, Tōyama Ichi-no-jō, Tōyama Saburō-shirō, Tōyama Tokurinsai, Tōyama Sanemon, Tōyama Naizen, and Tōyama Fujikura entered the 市丞丸 in the castle and killed themselves.  All other rebels were burned to death.

Supporters of the Takeda from Kai and Ina who were harboring in Iwamura Castle were permitted to return home via Kamimura through the direction of Ina but, at the Kinome Ridge to the south of Iwamura Castle, they were caught between Oda forces and all killed.  Upon learning of this development, Katsuyori returned to Kai.