Oyama Tomomasa (小山朝政)

Tomomasa OYAMA was a busho (Japanese military commander) from the end of the Heian period to the early Kamakura period.

It is said that he had served for MINAMOTO no Yoritomo since Yoritomo raised an army, and was appointed as Shimotsuke no kami (Governor of Shimotsuke Province) in addition to Shugo (a provincial constable) of Harima Province, and the record in "Azuma Kagami" (The Mirror of the East) (a historical account of the Kamakura Shogunate) that the job position in the year of his death was Jugoinoge (Junior Fifth Rank, Lower Grade), Shimotsuke no kami might be a writing error because he was 'Saemon no jo' (third ranked office of the Left Division of Outer Palace Guards) or 'hangan' (judge) in his late years, whose court ranks were Jurokui (Junior Sixth Rank) or Jushichii (Junior Seventh Rank), and the court rank of his father, Masamitsu, was Shoshichii (Senior Seventh Rank).

His birth

Around in 1154, he was born as a child of Masamitsu KOYAMA (a founder of the Koyama clan). His father was originally from the Ota clan in Musashi Province, and moved to Oyama, Shimotsuke Province, taking a new surname, Koyama, and got married to SAMUKAWA no Ama, a second wife, who was a daughter of Munetsuna Hatta, and a wet nurse of MINAMOTO no Yoritomo.

The Genpei War (Conflict from 1180 to 1185 between two warrior leagues, one under the Taira family [Heishi or Heike], and the other under the Minamoto family [Genji])

In 1180, MINAMOTO no Yoritomo took up arms to defeat the Taira clan, and on September 30, sent a letter to Tomomasa, urging him to participate in Yoritomo's troops. On October 29, SAMUKAWA no Ama joined Yoritomo with Tomomitsu YUKI, her biological child, and Tomomasa is thought to have followed Yoritomo soon after that.

In March, 1183, Yoritomo's shogunal retainers (of the Kamakura bakufu) were in Suruga Province (now part of Shizuoka Prefecture) to defense against the Taira clan which was said to attack Kamakura.

On the other hand, on March 22, MINAMOTO no Yoshihiro (SHIDA Saburo Senjo), who resided in Shida, Hitachi Province, raised arms to attack Kamakura, marching Shimotsuke Province with about 30,000 troops. Yoritomo pinned responsibility on Tomomasa in Shimotsuke Province to fight against Yoshihiro, and Tomomasa's brother Munemasa NAGANUMA departed Kamakura to support it.

On March 25, Yoshihiro marched his army to Kamakura, and invited Tomomasa to join his troops. Tomomasa answered Yoshihiro, dutifully lying that Tomomasa had fewer soldier then because his father served as Obanyaku (a job to guard Kyoto) in Kyoto with their soldiers. While Yoshihiro, glad to know that, made for Tomomasa's residence, Tomomasa and his warriors ambushed and attacked his troops on the way at Nogi-cho, shouting at the top of their voice to make them in panic. At that time, Tomomasa was 25 years old with young power, riding on horseback all around with his scarlet armor, and destroying many enemies. Hit by an arrow released by Yoshihiro, Tomomasa fell off his horse, non-lethal wound, and Tomomasa and Munemasa met and routed the Yoshihiro's troop in the east-south of Nogimiya, where Yoshihiro withdrew to take up Yoshihiro's position. This is called the Battle of Nogimiya.

On February 28, Tomomasa sent a messenger to tell his victory to Yoritomo. Yoritomo dispossessed territory of warriors in Hitachi Province, Shimotsuke Province and Kozuke Province, who had sided with Yoshihiro, and then awarded these territories to Tomomasa and his warriors.

On September 21, 1184, MINAMOTO no Noriyori left for Kyoto in order to pursue the Taira clan, and Tomomasa left Kamakura by an order to join Noriyori. Tomomasa was appointed as Hyoe no jo (Lieutenant of the Middle Palace Guards) in Kyoto, which he had requested at that time.

On March 6, 1185, Tomomasa departed from Suo Province to Bungo Province with Noriyori by ship. On April 19, while suffering from the deficiency of army provisions in Noriyori's troops, Tomomasa and other gokenin received a letter from Yoritomo expressing his gratitude for their efforts. On May 2, the Taira family was completely destroyed in the Battle of Dan no ura.

On May 23, Yoritomo issued a decree that any gokenin, including Tomomasa, who were appointed without permission should be prohibited to come back to their home land, and it said as follows.
It was like a lazy horse loitering away its time to have been appointed as any commission in Kyoto on the way to Chinzei (nickname of Kyushu).'

On November 24, being permitted, Tomomasa participated in the Buddhist memorial service of MINAMOTO no Yoshitomo held in Kamakura. This ceremony, which almost 3,000 gokenin attended, was held with the relationship between Yoritomo in Kamakura and Yoshitsune (another of Yoritomo's brothers) in Kyoto deteriorated. After the memorial ceremony, Yoritomo consolidated his gokenin and told them that he went up to Kyoto the next day. Yoritomo recruited volunteers among them who started at dawn, and Tomomasa was the first of those 58 volunteers. On December 1, the Yoritomo's troops reached the Kise-gawa River in Suruga Province, so that Yoshitsune fled from Kyoto without fighting against Yoritomo.

From then on, Tomomasa often participated in the ceremonies held in Kamakura.

The Battle of Oshu

On September 8, 1189, Yoritomo led troops from Kamakura to defeat FUJIWARA no Yasuhira in Oshu, and Tomomasa followed Yoritomo.

When Yoritomo stayed in Furutabashieki, Shimotsuke Province (now Utsunomiya City), where he prayed for victory at Utsunomiya Futaarayama-jinja Shrine on September 14, Tomomasa's father served meals for Yoritomo at his camp. Naoie KUMAGAI was there with Yoritomo, so that Masamitsu asked Yoritomo who he was, and Yoritomo answered that he was one of the bravest warriors in this country because he himself fought in the Genpei War as he had few vassals. Hearing that, Masamitsu raised the moral by telling Tomomasa, Munemasa NAGANUMA, Tomomitsu YUKI, Yoritsuna UTSUNOMIYA and his brothers to fight enough to be praised as the bravest warriors by Yoritomo. Yoritomo was amused to hear that.

On September 28, taking part in the Battle of Atsukashiyama, Tomomasa defeated FUJIWARA no Kunihira. On October 2, Tomomasa pursued Yasuhira into Monomioka, Tamatsukuri County, and surrounded the hill. Yasuhira had already fled away, and a fewer than 50 vassals remained there. Some of them were killed and some were captured by Tomomasa and his warriors.

In October, Yasuhira was killed by his own vassals, and the Battle of Oshu resulted in Yoritomo's victory.

Shukuro (members of Hyojoshu, a highest office of the Kamakura and Muromachi shogunates, where administrative matters and legal disputes were discussed in council) of Kamakura bakufu (Japanese feudal government headed by a shogun)

In winter, 1190, Tomomasa accompanied Yoritomo to Kyoto, and on December 10, he headed a procession when Yoritomo visited Iwashimizu Hachiman-gu Shrine. On January 15, 1191, Yoritomo recommended 10 gokenin, including Tomomasa, for their military exploits and appointed them as governmental officers, so that Tomomasa was promoted to Uemon no jo (third-ranked officer of the Right Division of Outer Palace Guards) from Uhyoue no jo (officer of the Right division of Middle Palace Guards).

On October 26, 1192, he was appointed as Jito (local land stewards) of Muratashimosho, Hitachi Province due to the exploit of the Battle of Nogimiya. He was promoted to Saemon no jo (third-ranked officer of the Left Division of Outer Palace Guards) at this time.

On November 25, 1199, he signed a letter appealing against Kagetoki FUJIWARA under joint signatures. On January 14, 1200, he was appointed as Shugo (the Governor of Harima Province) of Harima Province.

On March 16, 1201, while Tomomasa was serving as Obanyaku in Kyoto, his Sanjo Higashinotoin camp was attacked by Nagamochi JO, who called for a decree from the Imperial Court to attack the Kanto region. Tomomasa happened to be absent there because he guarded Emperor's procession, so his vassals staying in the shrine fought against Nagamochi and Nagamochi was retreated. Tomomasa, returning back, missed him in spite of leading troops into Kiyomizu-zaka Slope, where Nagamochi was said to hide, and Nagamochi was killed in Yoshino with his head exposed in the end.

On September 28, 1205, the Kamakura bakufu, suspicious of a rebellion of Yoritsuna UTSUNOMIYA, who was a Tomomasa's brother-in-law, discussed this matter in council at the residence of Masako HOJO; OE no Hiromoto insisted that Tomomasa should defeat Yoritsuna, but Tomomsa refused it, although in the case of the battle, he promised to fight against Yoritsuna by main force, not admitting Yoritsuna's rebel against the bakufu. On October 2, Yoritsuna and Tomomasa sent a letter to Yoshitoki HOJO saying that Yoritsuna had no conspiracy against the bakufu, but Yoritsuna was not forgiven, so that he renounced the world.

In 1221, Tomomasa remained in the Kanto region, but not went up to Kyoto as shukuro in the Jokyu War.

On November 26, 1223, he also served as kebiishi (officials with judicial and police power).

On May 22, 1238, he passed away at the age of 84. He died soon after he had fallen ill.
(These mentioned above originate from "Azuma Kagami")

His tomb is in Kazo City, Saitama Prefecture, and on June 16, 1959, it was designated as a historical site. According to Azuka Kagami, his official court rank when he passed away was Jugoinoge, Shimotsuke no kami, however, his job rank described in the same book was 'Saemon no jo' or 'hangan', whose court rank was Jurokui or Jushichii, so that his official court rank Jugoinoge, Shimotsuke no kami might be wrong.


The date-month-year of the historical events mentioned above is adopted from "Azuma Kagami" (old Japanese lunar calendar), and a New Year's Day of the Japanese Imperial era is converted to a year of the Christian era.