Battle of Hashidayama

Battle of Hashidayama
	Part of Genpei War
	; Image of Lake Saiko, around the area the battle is believed to have happened.
Date	August 25, 1180 Jishō calendar
Location	"Hashida Mountain", Suruga Province
Result	Minamoto clan victory
Belligerents
Minamoto clan	Taira clan
Commanders and leaders
Yasuda Yoshisada; Kudo Kagemitsu;	Kagehisa Matano [jp]; Tachibana no Tomochi [jp];

The Battle of Hashidayama (波志田山合戦) was one of the battles during the Genpei War, taking place in 1180. The location of Mount Hashida is assumed to be at the northern foot of Fuji,^[1] but the exact location is unknown due to various theories. This battle is what brought awareness to The Kai Minamoto clan [jp] in Japan.

Overview

According to Azuma Kagami,^[2] Prince Mochihito, son of Emperor Go-Shirakawa, issued a decree to the Minamoto clan in the east to defeat the Taira clan, which was sent to Minamoto no Yoritomo in Izu, Kai and Shinano provinces. Minamoto no Yoritomo raised an army in August of the same year, leading warriors from Izu and Sagami provinces, and was defeated on August 23rd at the Battle of Ishibashiyama by an army led by Ōba Kagechika of the Taira clan. ^[3]

Some clans were related to the Izu warriors close to Minamoto no Yoritomo, such as The Kai Minamoto [jp] (Ruled by the Takeda clan), founded by Minamoto no Yoshikiyo and his son Kiyomitsu [jp] in around 1131,^[4] who controlled the Kofu Basin area [jp]. Others, such as the Akiyama clan of Kagami Tohmitsu [jp] in Kai, and the Ogasawara clan in Shinano, served the Taira clan and/or had a residence in Kyoto.

Among the clans related to the Izu warriors, Kudo Kagemitsu agreed with Yoritomo's military expedition, and his family members, Shigemitsu and Chikamitsu, went to Yoritomo's side.^[5] Yoritomo hid in the Hakone Mountains after the defeat at Mt. Ishibashi, planning to dispatch Hōjō Tokimasa and Yoshitoki, father and son, to Kai province (according to Azuma Kagami),^[6] and it is believed that Yoritomo was aware of the existence of the Kai Minamoto.

According to Azuma Kagami, when the defeat at the Battle of Ishibashiyama was reported to Kai, the Kai Minamoto clan, led by Yasuda Yoshisada and Kudo Kagemitsu went to rescue Minamoto no Yoritomo (as well as other clans close to him).^[5]

On the Taira side, Kagehisa Matano, the younger brother of Kagechika Oba, dispatched an army to Kai together with Tachibana no Tomochi, the leader of the Suruga province, and the two armies clashed on August 25 at "Mount Hashida". The location of "Mount Hashida" is thought to be around Fujikawaguchiko Town/Mt. Ashiwada, located between Saiko Lake and Lake Kawaguchi at the northern foot of Fuji.^[7]

Battle

According to Azuma Kagami, 100 bowstrings of the Taira's army were broken by rats during a stay in a village.^[8] Soon after in the morning, he heard that Yasuda no Yoshisada, Kudo Kagemitsu, and his sons had become ready to fight a battle, and while the pro-Minamoto forces were setting out from Kai Province, they met Kagehisa and others at Hashidayama. The battle began with a strong attack by Yasuda's forces, consisting mostly of arrow barrages. Although the Taira forces did fight back, Kagehisa and his men had their bowstrings cut, and had to take up swords. Many of the Taira forces were killed. Yasuda's subordinates and others were also forced to take up swords at a point. However Kagehisa managed to flee.^[9] The Taira eventually left and were routed.^[10]

In the Sankai-ki [jp], Minamoto no/Nitta Yoshishige, the leader and founder of the Nitta clan, sent a letter to Fujiwara no Tadamasa [jp] (Tadamasa was the elder brother of Nakayama Tadachika, the author of the "Sankaiki"), a feudal lord close to the Taira clan, reporting Takeda Nobuyoshi, one of the leaders of the Kai Minamoto clan, as an anti-Taira force alongside Yoritomo. The victory at Mount Hashida is thought to have triggered awareness of the existence of the Kai Minamoto clan in the eastern part of Japan and elsewhere.^[11]

Aftermath

On August 28, Yoritomo escaped from Kanagawa Prefecture to Awa Province (Chiba) to rejoin his army and rallied many warriors in the East. The rest of the Minamoto and Takeda Nobuyoshi had received word of the Battle of Mount Hashida in early-mid September ^[12] and were asked to go to Suruga province to fight, however, Takeda Nobuyoshi, Ichijō Tadayori and others of the Kai Minamoto clan went to Ina County [jp], Shinano Province (modern day Nagano Prefacture) and defeated Taira Tomonori in modern day Komagane first.^[13] On November 9th, the Kai Minamoto clan, headed by Takeda Nobuyoshi, went to Suruga to fight the Taira force at the Battle of Fujigawa, which they won.

References

^ "１１８０年（治承四年)" [1180 (4th year of Jisei)]. Azuma Kagami. p. ８月２５日. 而るに昨日昏黒に及ぶの間、富士の北麓に宿すの処、景久並び / He was then in the northern foothills of Mount Fuji, where he lodged yesterday in the dark
^ In the English page for the Genpei War, after the sixth footnote, a mention to this battle is said (and i quote): "However he (Minamoto no Yoritomo) successfully made it to the provinces of Kai and Kōzuke, where the Takeda and other friendly families helped repel the Taira army."
^ "１１８０年（治承四年)" [1180 (4th year of Jisei)]. Azuma Kagami. 1260s. p. ８月２５日. 五郎景久、駿河の国の目代橘の遠茂が軍勢を相具し、武田・一條等の源氏を襲わんが"/"Goro Kagehisa of Matano and Tachibana no Toumochi of Suruga, with an army, went to the province of Kai to attack the Minamoto clans of Takeda, Ichijo, and others
^ "Yamanshi Prefecture". pref.yamanashi.jp (in Japanese). 1131年ころ、甲斐国には源義清、清光の親子が入り、甲斐源氏を興します [Around 1131, father and son Yoshikiyo and Kiyomitsu Minamoto entered Kai Province and established the Kai Minamoto clan.]
^ ^a ^b "１１８０年（治承四年、庚子）" [1180 (4th year of Jisei)]. Azuma Kagami. p. ８月２５日. 安田の三郎義定・工藤庄司景光、石橋に於いて合/Yoshisada Yasuda's Saburo Yoshisada and Kudo Shoji Kagemitsu,, heard of the battle at Ishibashi and met Kagehisa and others at Mount Hashita
^ According to "The Tale of the Heike", the Hojo father and son fled to Kai Province on their own initiative, regardless of Yoritomo's intentions.
^ "深読み吾妻鏡/波志太山合戦の顛末".
^ Azuma Kagami. に郎従帯する所の百余張の弓弦、鼠の為喰い切られをはんぬ/Kagehisa and his followers, more than a hundred bows and strings were eaten away by rats
^ "１１８０年（治承四年、庚子）" [1180 (4th year of Jisei)]. Azuma Kagami. p. ８月２５日. 然れども景久雌伏せしめ逐電すと/However, Kagehisa was forced to lie low and fled
^ "１１８０年（治承四年、庚子）" [1180 (4th year of Jisei)]. Azuma Kagami. p. ８月２５日. 依って、太刀を取ると雖も、矢石を禦ぐこと能わず/Therefore, even though they took up swords, they could not defend themselves against the arrow stones.
^ 秋山敬「源頼朝の挙兵と甲斐源氏」『山梨県史』
^ "１１８０年（治承四年、庚子）" [1180 (4th year of Jisei)]. Azuma Kagami. p. ９月１０日. "甲斐の国の源氏武田の太郎信義・一條の次郎忠頼以下、石橋合戦の事を聞き、武衛を尋ね奉り、駿河の国に参向せんと欲す/Nobuyoshi of Takeda, Jiro Tadayori of Ichijo and others of the Minamoto clan in the Land of Kai heard of the Battle of Mount Hashida and asked for the military assistance to go to Suruga Province.
^ "１１８０年（治承四年、庚子）" [1180 (4th year of Jisei)]. Azuma Kagami. p. ９月１０日. 而るに平氏の方人等信濃の国に在りと。仍って先ず彼の国に発向す/The Taira clan's men and others were in Shinano. Therefore I shall first set out for his country.

Sources

Azuma Kagami (in Japanese)
English translation of The Tale of the Heike (archived)
https://history.orange-shoes.biz/深読み吾妻鏡/波志太山合戦の顛末/ (Secondary)
https://ameblo.jp/oyomaru-0826/entry-12415959663.html (Secondary)

[1] "１１８０年（治承四年)" [1180 (4th year of Jisei)]. Azuma Kagami. p. ８月２５日. 而るに昨日昏黒に及ぶの間、富士の北麓に宿すの処、景久並び / He was then in the northern foothills of Mount Fuji, where he lodged yesterday in the dark

[2] In the English page for the Genpei War, after the sixth footnote, a mention to this battle is said (and i quote): "However he (Minamoto no Yoritomo) successfully made it to the provinces of Kai and Kōzuke, where the Takeda and other friendly families helped repel the Taira army."

[3] "１１８０年（治承四年)" [1180 (4th year of Jisei)]. Azuma Kagami. 1260s. p. ８月２５日. 五郎景久、駿河の国の目代橘の遠茂が軍勢を相具し、武田・一條等の源氏を襲わんが"/"Goro Kagehisa of Matano and Tachibana no Toumochi of Suruga, with an army, went to the province of Kai to attack the Minamoto clans of Takeda, Ichijo, and others

[4] "Yamanshi Prefecture". pref.yamanashi.jp (in Japanese). 1131年ころ、甲斐国には源義清、清光の親子が入り、甲斐源氏を興します [Around 1131, father and son Yoshikiyo and Kiyomitsu Minamoto entered Kai Province and established the Kai Minamoto clan.]

[:1-5] "１１８０年（治承四年、庚子）" [1180 (4th year of Jisei)]. Azuma Kagami. p. ８月２５日. 安田の三郎義定・工藤庄司景光、石橋に於いて合/Yoshisada Yasuda's Saburo Yoshisada and Kudo Shoji Kagemitsu,, heard of the battle at Ishibashi and met Kagehisa and others at Mount Hashita

[:0-6] According to "The Tale of the Heike", the Hojo father and son fled to Kai Province on their own initiative, regardless of Yoritomo's intentions.

[7] "深読み吾妻鏡/波志太山合戦の顛末".

[8] Azuma Kagami. に郎従帯する所の百余張の弓弦、鼠の為喰い切られをはんぬ/Kagehisa and his followers, more than a hundred bows and strings were eaten away by rats

[9] "１１８０年（治承四年、庚子）" [1180 (4th year of Jisei)]. Azuma Kagami. p. ８月２５日. 然れども景久雌伏せしめ逐電すと/However, Kagehisa was forced to lie low and fled

[10] "１１８０年（治承四年、庚子）" [1180 (4th year of Jisei)]. Azuma Kagami. p. ８月２５日. 依って、太刀を取ると雖も、矢石を禦ぐこと能わず/Therefore, even though they took up swords, they could not defend themselves against the arrow stones.

[11] 秋山敬「源頼朝の挙兵と甲斐源氏」『山梨県史』

[12] "１１８０年（治承四年、庚子）" [1180 (4th year of Jisei)]. Azuma Kagami. p. ９月１０日. "甲斐の国の源氏武田の太郎信義・一條の次郎忠頼以下、石橋合戦の事を聞き、武衛を尋ね奉り、駿河の国に参向せんと欲す/Nobuyoshi of Takeda, Jiro Tadayori of Ichijo and others of the Minamoto clan in the Land of Kai heard of the Battle of Mount Hashida and asked for the military assistance to go to Suruga Province.

[13] "１１８０年（治承四年、庚子）" [1180 (4th year of Jisei)]. Azuma Kagami. p. ９月１０日. 而るに平氏の方人等信濃の国に在りと。仍って先ず彼の国に発向す/The Taira clan's men and others were in Shinano. Therefore I shall first set out for his country.

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