On the night of September 23, 785 (Enryaku 4).
Fujiwara no Tanetsugu, who was responsible for the construction of the new capital, Nagaoka-kyo, was shot with an arrow by an unknown assailant.
Tanetsugu was a central figure in the court, entrusted by Emperor Kanmu to oversee the ongoing construction of the capital after the relocation.
On the following day, September 24, Tanetsugu passed away. Sources like the “Yamakawa Nihonshi Kojiten” also record his death on September 24.
After the assassination, investigations and repercussions proceeded swiftly.
Many officials, including Otomo no Tsugito, were condemned, and the inquiry extended to Prince Sawara, Emperor Kanmu’s brother and the Crown Prince.
Prince Sawara was confined to Otsukuri Temple and stripped of his title as Crown Prince. He died while being transferred to Awaji Province.
Otomo no Yakamochi, who had died about a month before the incident, was also posthumously implicated in the assassination and removed from the official register.
However, the assassination of Fujiwara no Tanetsugu did not immediately lead to the abandonment of Nagaoka-kyo.
Construction continued after the incident, with the Daijokan-in completed in 786 and various gates of Heijo Palace moved to Nagaoka Palace by 791.
Meanwhile, the death of Prince Sawara left a lasting impact on the court.
Eventually, an illness of the Crown Prince was attributed to “the curse of Prince Sawara,” prompting the court to attempt to appease his spirit.
In 793, construction of a new capital began in Kadono.
Was the assassination of Fujiwara no Tanetsugu the direct cause of the relocation to Heian-kyo?
We will trace the events following the assassination in September 785, focusing on Nagaoka-kyo and Prince Sawara.
1. The Year 784—The Beginning of Nagaoka-kyo’s Construction
In 784 (Enryaku 3).
Emperor Kanmu advanced plans to move from Heijo-kyo to a new capital.
The chosen site was around Nagaoka Village in Otokuni District, Yamashiro Province.
On May 16, Fujiwara no Kurokimaro and others inspected Nagaoka Village.
By June 10, Fujiwara no Tanetsugu and others were appointed to oversee the construction of Nagaoka Palace, and the building of the capital and palace began.
On November 11, Emperor Kanmu moved to Nagaoka-kyo.
The relocation to Nagaoka-kyo is sometimes explained as a move to distance from the powerful temples of Nara.
The relationship with the Buddhist powers in Nanto cannot be ignored, but it alone does not explain the relocation.
The location of Nagaoka was advantageous for both water and land transportation, being near the Yodo River system.
In 787, an edict was issued stating that the relocation to Nagaoka was due to its convenient water and land transport.
Nagaoka-kyo was not intended as a temporary capital to be used for only a short period.
The construction of a full-fledged capital, with palaces, government offices, roads, and markets, was underway.
One of the key officials at the center of this project was Fujiwara no Tanetsugu.
2. Fujiwara no Tanetsugu—The Trusted Official of Emperor Kanmu
Fujiwara no Tanetsugu was born in 737 (Tenpyo 9).
He was the grandson of Fujiwara no Umakai, the founder of the Fujiwara Shikike branch, with Fujiwara no Kiyonari as his father and the daughter of Qin Chogen as his mother.
During the reign of Emperor Kōnin, he rose in rank, and after Emperor Kanmu ascended the throne, he advanced further.
In the first year of Enryaku (782), he became a councilor, and by January of Enryaku 3 (784), he was promoted to Middle Counselor.
That same year, he inspected Nagaoka Village with Fujiwara no Kuro Maro and others, and in June, he was appointed as the official in charge of constructing Nagaoka Palace.
Tanetsugu gained the trust of Emperor Kanmu and became a central figure in the practical work of building Nagaoka-kyō.
On his mother’s side, he was connected to the Hata clan, which held influence around the Yamashiro Province.
These personal connections provide material for considering the background of Nagaoka-kyō’s construction, but they alone cannot explain the reasons for the capital’s relocation.
The relocation was a national project led by Emperor Kanmu and carried out by many court nobles and officials.
Tanetsugu played an important role within this endeavor.
3. Night of September 23, 785—Tanetsugu is Shot
In September of Enryaku 4 (785).
Emperor Kanmu was on an imperial visit to the Heijō area.
At Nagaoka Palace, Fujiwara no Korekimi and Fujiwara no Tanetsugu remained as officials in charge, and Prince Sawara was also present as the crown prince.
According to related historical materials compiled by the Nara National Research Institute for Cultural Properties, it is confirmed that at the hour of the boar on September 23, Tanetsugu was shot with an arrow by bandits.
The “Shoku Nihongi” records that “two arrows pierced his body.” Tanetsugu died the following day, on the 24th.
The timeline of Nagaokakyō City places the attack near the area of Shimasaka.
Less than a year after the relocation to Nagaoka-kyō, the central figure in its construction was assassinated.
What was even more unusual was the speed of the subsequent punishments.
4. September 23 and 24—Rapid Progress of Punishments
On September 23, the day of the attack.
Tajihi no Hamahito, one of those accused of attacking Tanetsugu, was executed at Ōe Mountain.
On the following day, the 24th, dozens of people, including Ōtomo no Tsugito and Takeyoshi, were condemned, and Hōki no Fumamaro and Oshika no Kizumamaro, who were said to have shot Tanetsugu, were executed south of Yamasaki Bridge.
The punishments began on the day Tanetsugu was shot, and by the next day, the investigation had expanded to many officials.
Ōtomo no Tsugito is later noted in biographical dictionaries as a central figure in the Tanetsugu assassination incident.
However, it is necessary to separately consider how the investigation was specifically conducted and to what extent the obtained confessions reflected the reality of the incident.
It is confirmed that the court treated this assassination not as the act of a single individual but as a political incident involving multiple officials.
Moreover, the name of the crown prince was incorporated into the narrative of the incident.
5. The Court’s Depiction of the Assassination Incident
Regarding the Tanetsugu assassination incident, the “Shoku Nihongi” and “Nihon Kiryaku” convey the confessions and punishments of those involved.
In these accounts, officials from the Ōtomo and Saeki clans are said to have conspired in the assassination, and the incident is positioned within the context of a plot with Ōtomo no Yakamochi and connections to Prince Sawara.
However, the Nara National Research Institute for Cultural Properties points out that multiple revisions were made to the “Shoku Nihongi” articles concerning the Fujiwara no Tanetsugu assassination incident.
Therefore, the confessions recorded in the court’s investigation cannot be taken as a complete representation of the incident.
Explaining why Tanetsugu was targeted is not straightforward with just one reason.
There were political relationships between Fujiwara no Tanetsugu, who rapidly rose in rank under Emperor Kanmu’s trust, and the traditional powerful clans like the Otomo and Saeki families.
Interests surrounding the relocation and construction of Nagaoka-kyo.
The power dynamics within the early Kanmu administration.
Multiple backgrounds have been pointed out.
What can be reliably traced from historical records is that the investigation following Tanetsugu’s assassination expanded to many officials, ultimately leading to the punishment of Crown Prince Sawara.
6. September 28 — Prince Sawara Sent to Otsukyo Temple
Prince Sawara was the son of Emperor Kōnin and the younger brother of Emperor Kanmu.
Originally active as a monk, he became the crown prince when Emperor Kanmu ascended the throne in 781.
However, during the investigation of Fujiwara no Tanetsugu’s assassination, suspicion also fell on Prince Sawara.
On September 28.
Prince Sawara was returned from the imperial palace to the crown prince’s residence and was confined to Otsukyo Temple that same day.
It is said that testimonies from those involved in the incident linked Prince Sawara’s name to the assassination.
However, there is no independent evidence confirming that Prince Sawara ordered Tanetsugu’s assassination.
The extent of Prince Sawara’s actual involvement in the incident remains uncertain.
Eventually, Prince Sawara was deposed as crown prince.
He was then sentenced to exile in Awaji Province.
7. The Death of Prince Sawara, Who Proclaimed His Innocence
Confined at Otsukyo Temple, Prince Sawara proclaimed his innocence.
It is reported that he refused food and drink in protest.
Subsequently, he was to be sent to Awaji Province, but he never reached his destination.
More than ten days after his confinement, he died near Takase Bridge while being transported to Awaji.
The timeline of Nagaokakyo City also records that he died during transport more than ten days after his confinement on September 28.
It is said that his remains were sent to Awaji as they were.
On November 25, Emperor Kanmu’s son, Prince Anen, was appointed the new crown prince.
The assassination of Fujiwara no Tanetsugu was not just an incident where the person responsible for the capital’s construction died.
As a result, even the crown prince was replaced, leading to significant changes in the imperial succession.
8. Even the Deceased Otomo no Yakamochi Was Punished
Otomo no Yakamochi, known for the “Manyoshu,” was also questioned for involvement in Fujiwara no Tanetsugu’s assassination.
However, Yakamochi had already passed away by the time the incident occurred.
August 28, Enryaku 4 (785).
About a month before Tanetsugu’s assassination.
Nevertheless, he was removed from the official register for alleged involvement in the incident, and his family also faced consequences.
Determining the extent of Yakamochi’s actual involvement in the assassination plan is not possible from the remaining testimonies alone.
On the other hand, the fact that even a deceased person was targeted for punishment indicates that the court treated Tanetsugu’s assassination as a broad political incident.
Iemochi was reinstated in the year Daidō 1 (806).
9. The Continued Construction of Nagaoka-kyō After the Assassination
Even after the assassination of Fujiwara no Tanetsugu, the construction of Nagaoka-kyō did not cease.
On July 19, Enryaku 5 (786).
The Daijōkan Hall was completed, and for the first time, the officials took their seats in the morning assembly.
In Enryaku 6 (787), Emperor Kanmu issued an edict stating that the capital was placed in Nagaoka due to the convenience of water and land transportation.
Furthermore, by Enryaku 10 (791), the project to dismantle the gates of Heijō Palace and relocate them to Nagaoka Palace was underway.
Even six years after Tanetsugu’s assassination, the court continued to develop Nagaoka-kyō.
This fact is crucial when considering the relationship between the assassination of Fujiwara no Tanetsugu and the relocation to Heian-kyō.
“Because Tanetsugu was assassinated, Emperor Kanmu immediately abandoned Nagaoka-kyō”
was not the sequence of events.
Even after the incident in 785, Nagaoka-kyō continued to be developed as the capital.
The significant changes became apparent only after entering the 790s.
10. 792—The “Curse” of Prince Sawara and Floods
Enryaku 11 (792).
Seven years had passed since the Tanetsugu assassination incident.
Around this time, Crown Prince Ate became ill, and divination determined that it was due to the curse of Prince Sawara.
The court sent envoys to Awaji to appease the spirit of Prince Sawara.
Prince Sawara had become an entity that the court could not ignore, even after his death.
In the same year, heavy rains and floods occurred around Nagaoka-kyō.
These events led to the widespread belief in later generations that Emperor Kanmu abandoned Nagaoka-kyō due to Prince Sawara’s vengeful spirit and the floods. It is confirmed that the court at the time recognized Prince Sawara’s curse as a real issue.
However, it is not possible to explain the relocation to Heian-kyō solely by the vengeful spirit or the floods.
Factors such as the burden of constructing Nagaoka-kyō, the urban environment, and political circumstances must also be considered.
Then, in the following year, 793, the court began to take concrete steps towards building a new capital.
11. 793—The Beginning of New Capital Construction in Kadono
Enryaku 12 (793), New Year.
Senior Counselor Fujiwara no Oguro Maro and others conducted an on-site survey of the Uda area in Kadono District, Yamashiro Province, as a candidate site for the new capital.
Following this, the construction of the new capital began.
Soon after, the dismantling of the imperial palace in Nagaoka-kyō commenced, and Emperor Kanmu moved to another location.
The court did not suddenly abandon the capital overnight while continuing to develop Nagaoka-kyō.
After several years of continuing the construction of Nagaoka-kyō following the 785 assassination of Tanetsugu, the move to a new capital began to materialize between 792 and 793.
And in the following year, 794, the capital moved once again.
12. 794—From Nagaoka-kyō to Heian-kyō
Enryaku 13 (794), October 22.
Emperor Kanmu moved from Nagaoka-kyō to the new capital.
On October 28, an imperial edict was issued to relocate the capital.
Then, on November 8,
the new capital was named “Heian-kyo,” and the province “Yamashiro no Kuni” was renamed “Yamashiro no Kuni.”
It had been about ten years since the move to Nagaoka-kyo.
And nine years had passed since the assassination of Fujiwara no Tanetsugu.
During this time, the imperial court continued the construction of Nagaoka-kyo.
Meanwhile, the assassination led to the downfall and death of Crown Prince Sawara, whose spirit was later believed to have caused illness in the crown prince.
Floods also occurred, and by 793, construction of a new capital began in Kadono.
Given these events, it is not sufficient to explain the assassination of Fujiwara no Tanetsugu as merely the “direct trigger for the relocation to Heian-kyo.”
The impact of the incident on the Nagaoka-kyo regime was broader than that.
Fujiwara no Tanetsugu, the central figure in the construction of Nagaoka-kyo, was killed.
Many officials, including those from the Otomo and Saeki clans, were punished.
Crown Prince Sawara was deposed and died during his exile.
Prince Anen was appointed as the new crown prince, but the death of Prince Sawara continued to be perceived as a “curse” by the court.
Meanwhile, the construction of Nagaoka-kyo itself continued for several years after the assassination.
The assassination of Fujiwara no Tanetsugu cannot be defined solely by the relocation to Heian-kyo.
It was a major political incident in the early Kanmu era, occurring within the core of the regime during the construction of the new capital, shaking the foundations of city building, the officialdom, and the succession to the throne simultaneously.
📚 ‘Fujiwara no Tanetsugu—Moving the Capital to Nagaoka’
This book is recommended for those who want to deeply understand the assassination of Fujiwara no Tanetsugu through his life and involvement in the construction of Nagaoka-kyo.
By delving into the relationship with Emperor Kanmu and the political situation of the time, which this article could not cover, you can further uncover the background of **”why Tanetsugu was targeted?”**
🍵 Kyoto Ninomaru Gate “Nama Yatsuhashi”
After learning about the history of Heian-kyo, you might find it interesting to try Nama Yatsuhashi, a traditional Kyoto confection.
It’s a quintessentially Kyoto treat that lets you savor the flavors of red bean paste and cinnamon while reflecting on Kyoto’s history.
📜 The Assassination of Fujiwara no Tanetsugu: Key Timeline
| Date | Event |
|---|---|
| June 10, 784 | Fujiwara no Tanetsugu and others appointed to oversee the construction of Nagaoka Palace |
| November 11, 784 | Emperor Kanmu relocates to Nagaoka-kyo |
| January 1, 785 | New Year’s celebration at the Daigokuden of Nagaoka Palace |
| July 785 | 314,000 workers recruited from various provinces for the construction of Nagaoka Palace |
| September 23, 785 | Fujiwara no Tanetsugu is attacked |
| September 24, 785 | Tanetsugu dies. Otomo no Tsugito and Takeyoshi are executed |
| September 28, 785 | Prince Sawara is confined to Otsukuri Temple |
| October 785 | Prince Sawara dies while being transferred to Awaji |
| November 25, 785 | Prince Anon is named Crown Prince |
| 792 | The spirit of Prince Sawara is blamed for Prince Anon’s illness |
| 792 | Severe flooding occurs in Nagaoka-kyo |
| 793 | Emperor Kanmu inspects Katsura and plans a new capital |
| October 22, 794 | The capital is moved to Heian-kyo |
