Honnō-ji Incident

thumb|An [[ukiyo-e by Yoshitoshi depicting Nobunaga fighting in the Honnō-ji Incident.]]

The was the attempted assassination of Japanese daimyo Oda Nobunaga at Honnō-ji, a temple in Kyoto, on 21 June 1582 (2nd day of the sixth month, Tenshō 10). Nobunaga was on the verge of unifying the country, but died by seppuku in the unexpected rebellion of his vassal Akechi Mitsuhide.

Nobunaga only had a few guards and retainers with him when he was attacked, ending his Sengoku period campaign to unify Japan under his power. Nobunaga's death was avenged two weeks later when his retainer Toyotomi Hideyoshi defeated Mitsuhide in the Battle of Yamazaki, paving the way for Hideyoshi to complete the unification of Japan.

Mitsuhide's motive for assassinating Nobunaga is unknown, though there are multiple theories for his betrayal.

Background

By 1582, Oda Nobunaga was the most powerful daimyo in Japan. He was continuing a sustained campaign of unification in the face of the ongoing political upheaval that characterized Japanese history during the Sengoku period. Nobunaga had destroyed the Takeda clan earlier that year at the Battle of Tenmokuzan and had central Japan firmly under his control, with his only rivals, the Mōri clan and the Uesugi clan, both weakened by internal affairs. The death of Uesugi Kenshin left the Uesugi clan devastated by an internal conflict between his two adopted sons. The Mōri clan was also in a situation where defeat was almost inevitable and had presented a peace proposal to Hashiba Hideyoshi, offering the cession of five provinces. The nearly decade-long Ishiyama Hongan-ji War had already ended with the defeat of the Ikkō-ikki.

It was at this point that Nobunaga began sending his generals aggressively in all directions to continue his military expansion. Nobunaga ordered Hashiba Hideyoshi to attack the Mōri clan in the Chūgoku region; Niwa Nagahide to prepare for an invasion of Shikoku; Takigawa Kazumasu to watch the Hōjō clan from Kōzuke Province and Shinano Province; and Shibata Katsuie to invade Echigo Province, the home domain of the Uesugi clan. then in Nihon Gaishi by Rai San'yō, a kangakusha of the late Edo period, and is most likely a creation, not a statement by Mitsuhide himself.

According to Luís Fróis's "History of Japan" and testimonies from surviving soldiers, Mitsuhide was only the commander of the Oda army's area forces, and since it was the Oda clan to whom the soldiers owed allegiance, Mitsuhide did not reveal his purpose to anyone except his officers, fearing that informants might appear. Even when the attack actually began, the soldiers did not know whom they were attacking, and some thought it was Ieyasu.

Chronology of the incident

The situation at the time was recorded by Gyū-ichi Ota, the author of "Shinchō Kōki", who interviewed the ladies-in-waiting who were at the scene soon after the incident.

Nobunaga had come to Kyoto to support Hashiba Hideyoshi and stayed at Honnō-ji on this day. This was because Nobunaga had not dared to build a castle in Kyoto in order to maintain a distance from the Imperial Court. It was said that Nobunaga then entered the back room of the palace, closed the door of the storage room, and committed seppuku in the burning temple.

The Kiyosu Conference was then held to determine the successor to the Oda clan, consisting of four vassals of the Oda clan, Shibata Katsuie, Niwa Nagahide, Ikeda Tsuneoki, and Hashiba Hideyoshi. Three possible successors were discussed; Nobukatsu, the second son; Nobutaka, the third son; and Hidenobu (Sanhōshi), Nobutada's eldest son, or Nobunaga's three-year-old grandson.

Nobunaga's corpse

After defeating Mitsuhide, Hideyoshi searched for Nobunaga's body but was unable to locate it. In October 1582, Hideyoshi held Nobunaga's funeral at Daitoku-ji Temple in Kyoto. To represent his missing body, Hideyoshi used a life-size wooden statue of Nobunaga, then cremated and put the ashes in an urn. However, the Tokugawa Nikki theory was doubted by modern historians, since it was not the shortest route for Ieyasu to reach Mikawa from his starting position at Sakai, while on the other hand, it was also considered by historians as a very risky path due to the existence of Iga ikki groups, which were hostile to the Oda and Tokugawa clans.

200px|thumb|right|Kada pass is believed to be the road that was taken by Ieyasu Tokugawa to return to Mikawa province.

Regardless of which theory is true, historians agreed that the track ended at Kada (a mountain pass between Kameyama town and Iga), and that the Tokugawa group suffered a last attack by the Ochimusha-gari outlaws at the Kada pass, where they reached the territory of the Kōka ikki clans of Jizamurai, which were friendly to the Tokugawa clan. The Koka ikki Jizamurai assisted Ieyasu in eliminating the threats of the Ochimusha-gari outlaws and escorted them until they reached Iga Province, where they were further protected by other friendly groups of Iga ikki, which accompanied the Ieyasu group until they safely reached Mikawa. 34 recorded Tokugawa vassals survived this journey, such as Sakai Tadatsugu, Ii Naomasa, Honda Tadakatsu, Sakakibara Yasumasa, and many others. Other than those four Shitennō generals, Matsudaira Ietada recorded in his journal, Ietada nikki (家忠日記), the escorts of Ieyasu during the journey in Iga consisted of:

Ietada Nikki also recorded that the escorts of Ieyasu suffered around 200 casualties during their journey.

However, not all of the escaping parties managed to escape alive. Anayama Nobutada, a former Twenty-Four Generals of Takeda Shingen member who was now an ally to the Tokugawa and Nobunaga clan, was ambushed by the Ochimusha-gari during the journey, and killed along with some of his retainers.

However, a modern scholar such as Tatsuo Fujita doubted the credibility of Hattori Hanzō's ninja army theory, since it first appeared in the Iga-sha yuishogaki record, which circulated in the Edo period during the rule of Shogun Tokugawa Yoshimune. It has been argued that the circulation of the myth about Hattori Hanzō's ninja army helping Ieyasu was created as propaganda to increase the prestige of the Iga and Koka clan confederations in the Tokugawa Shogunate.

Mitsuhide's betrayal theories

The Honnō-ji Incident is a major historical event, but no definitive conclusion has been reached regarding Akechi Mitsuhide's motives, and the truth remains unknown. More than 50 theories have been proposed over the years, and new theories emerge with each discovery of a new historical document or announcement of the results of an excavation. However, historian Tetsuo Owada considered such history, including Mitsuhide's alleged letter to Kobayakawa Takakage expressing his feelings about Nobunaga, as unreliable. Furthermore, some theorize that Nobunaga forcibly transferred Mitsuhide from his territorial control of Sakamoto and Tanba into the yet-to-be-conquered regions of Izumo and Iwami. However, this theory was also dismissed by Owada as it was a usual custom for Nobunaga to bestow non-pacified territories to his vassals as promise. Modern historian Watanabe Daimon explained that this theory was traced from Toyama Nobuharu's work "Sōkenki" written around 1658; "Kashiwazaki Monogatari"; and also "Nobunaga-ki" (Shinchō Kōki); which Daimon also doubted their credibilities due to many embellishments and additions which was not found in primary sources found.

Thus, these stories were largely deemed by historians as unreliable, including the story of Mitsuhide's betrayal from "Akechi-gunki" and "Kōyō Gunkan".

Ashikaga Shogunate restoration, Tatsuo Fujita points out that Mitsuhide's handwritten letter addressed to the Kishu daimyo named Shigeharu Dobashi shows that Mitsuhide had a clear plan to welcome Yoshiaki to Kyoto after the Honnoji Incident and restore the Muromachi Shogunate.

Alleged collaborators

The mastermind theory that someone behind the incident manipulated Mitsuhide to carry out Nobunaga's assassination is surprisingly new and has emerged since the 1990s. It all started when the well-known historian who specialized in Japanese medieval history, Akira Imatani, published a book advocating a conflict between the Imperial Court and Nobunaga. The theory is that the existence of an emperor with high authority was becoming a hindrance to Nobunaga, who wanted to be an absolute monarch. At the time, when the new emperor was about to ascend to the throne, the emperor system was the subject of much debate in the historical academia. Although Imatani himself did not claim that the Imperial Court was involved in the Honnō-ji Incident, various conspiracy theories were developed, mainly by influential historical researchers who were inspired by Imatani's theory.

The reason is that Hideyoshi's Chugoku Ogaeshi was too fast. However, only the cavalry warriors were able to turn back at breakneck speed, and the infantry arrived late. Many of the soldiers did not make it in time for the "Battle of Yamazaki" with Mitsuhide.
Tokugawa Ieyasu theory In 2020, NHK aired a program called "Honnoji Incident Summit 2020". Seven historians debated various theories, with the "Shikoku theory" garnering the most support.

In popular culture

Honnōji Hotel is a 2017 comedy mystery drama that takes place around the Honnō-ji Incident.
The incident is closely portrayed in the first act of the 2025 video game Assassin's Creed Shadows.

Appendix

Footnotes

References

Bibliography

de Lange, William (2020). Samurai Battles: The Long Road to Unification. Toyo Press. .
Naramoto Tatsuya (1994). Nihon no Kassen. Tokyo: Shufu to Seikatsusha.