Honnō-ji Incident

The Honnō-ji Incident (本能寺の変, Honnō-ji no Hen) was the 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 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.
By 1582, Oda Nobunaga was the most powerful daimyo in Japan and 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 also by an internal conflict between his two adopted sons, weaker than before. The nearly decade-long Ishiyama Hongan-ji War also had already ended with the conclusion of peace. The Mori 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.
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.
Nobunaga, confident of unifying the country after destroying the Takeda clan, returned to Azuchi in high spirits. Tokugawa Ieyasu also came to Azuchi Castle to thank Nobunaga for giving him the Suruga province. However, around this time, the Mōri clan launched a large-scale counteroffensive in the Chūgoku region, and Nobunaga received a request for reinforcements from Hashiba Hideyoshi, whose forces were stuck besieging the Mōri-controlled Takamatsu Castle.
Nobunaga immediately ordered Akechi Mitsuhide to go to the Chugoku region to support Hideyoshi, and he himself was to follow soon after. Nobunaga began his preparations and headed for Honnō-ji in Kyoto, his usual resting place when he stopped by in the capital.
Nobunaga was unprotected at Honnō-ji, deep within his territory, with the only people he had around him being court officials, merchants, upper-class artists, and dozens of servants. Having dispatched most of his soldiers to take part in various campaigns, only a small force was left to protect his person and there was little fear that anyone would dare strike Nobunaga; security measures were weak. Taking advantage of this opening, Mitsuhide suddenly turned against his master.
Upon receiving the order, Mitsuhide returned to Sakamoto Castle and moved to his base in Tanba Province. He engaged in a session of renga with several prominent poets, using the opportunity to make clear his intentions of rising against Nobunaga. Mitsuhide saw an opportunity to act, when Nobunaga was not only resting in Honnō-ji and unprepared for an attack, but all the other major daimyō and the bulk of Nobunaga's army were occupied in other parts of the country. Mitsuhide led his army toward Kyoto under the pretense of following the order of Nobunaga. It was not the first time that Nobunaga had demonstrated his modernized and well-equipped troops in Kyoto, so Mitsuhide's men marching toward Kyoto did not raise any suspicion. Before dawn, Mitsuhide, leading 13,000 soldiers, suddenly changed course in the middle of his march and attacked Honnō-ji, where Nobunaga was staying.
There's a legend that when crossing the Katsura River, Mitsuhide announced to his troops that "The enemy awaits at Honnō-ji!" (敵は本能寺にあり, Teki wa Honnō-ji ni ari). However, this story appeared first in Oda Nobunaga-fu (織田信長譜) by Hayashi Razan (1583 – 1657) 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 Akechi 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.
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. Moreover, Nobunaga had ordered his generals to go into battle, so only about 150 men were escorting him at Honnō-ji. Akechi Mitsuhide, on the other hand, was leading 13,000 fully armed soldiers. This was a perfect opportunity for Mitsuhide. Honnō-ji was a fortified temple with stone walls and a moat, and it had a reasonable defense capability, but it was helpless when surrounded by a large army.
On that day, Kyoto seemed to be in the midst of bad weather due to the combination of abnormal weather and the rainy season. The attack began early in the morning. Mitsuhide's forces finished encircling Honnō-ji around 6:00 a.m. and began to invade the temple from all sides.
According to Shinchō Kōki, Nobunaga and the pages at first thought that someone had started a fight in the street. But when the enemy raised a battle cry and started shooting, they realized it was a rebellion. Nobunaga asked, "Whose scheme is this?", and Mori Ranmaru replied, "It appears to be Akechi's". Nobunaga did not ask back, but simply said, "There is no need to discuss the pros and cons./There is no choice." (是非に及ばず, Zehi ni oyobazu), and began to fight back with bows and arrows at the edge of the palace. When the bowstring broke, he kept shooting arrows while changing bows, and when he ran out of spare bows, he fought with his spear. When Nobunaga was eventually unable to fight after being hit in the elbow by an enemy spear, he retreated and told the nyōbō-shū there, "I don't care, you ladies hurry up and get out of here". 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 Akechi forces lifted the siege around 8:00 a.m.
Meanwhile, Oda Nobutada, who was at Myōkaku-ji Temple, received news of Mitsuhide's rebellion and attempted to go to Honnō-ji to rescue his father. However, just as he was leaving the temple, Murai Sadakatsu and his sons rushed in and stopped him. Murai said that Honnō-ji had already burned down and the enemy would soon attack us, and advised Nobutada to hunker down in the fortified Nijō Gosho. Upon entering the Nijō Gosho, Nobutada ordered Maeda Geni to flee with his infant son, Sanpōshi (Oda Hidenobu), going from Gifu Castle in Mino to Kiyosu Castle in Owari. Nobutada had all the people escape, including the kugyō and the nyōbō-shū, and then he began his war council. Some advised Nobutada to escape and head for Azuchi, but he said, "An enemy who has committed such a rebellion will not let us escape so easily. It would be a disgrace for me to be killed by common soldiers while fleeing", and decided to stay in Kyoto and fight. In the meantime, Akechi completed the siege of Nijō Gosho, making it impossible to escape. Later, Nobutada also committed seppuku. Kamata Shinsuke, who assisted Nobutada in his suicide, hid his head and body according to his instructions.
Akechi Mitsuhide was eager to find Nobunaga's body in the burnt ruins of Honnō-ji, but he was unable to locate it. Nobunaga's body not being found meant that no one knew if he was alive or dead and created a problem for Mitsuhide. If, by any chance, Nobunaga was alive, the probability of Mitsuhide's defeat increased, and even if it remained unclear whether he was alive or dead, Mitsuhide would find it very difficult to gain support from those who feared Nobunaga's retaliation. In fact, Hideyoshi sent a letter to Nobunaga's vassals that falsely claimed that Nobunaga was still alive to request their cooperation in defeating Mitsuhide. If Mitsuhide had obtained Nobunaga's head, he could have made his death known to the public, and some forces might have followed him. If that had happened, he might have been able to defeat Hideyoshi. Meanwhile, Mitsuhide also tried to persuade Oda vassals in the vicinity of Kyoto to recognize his authority after the death of Nobunaga. Then, Mitsuhide entered Nobunaga's Azuchi Castle east of Kyoto and began sending messages to the Imperial Court to boost his position and force the court to recognize his authority as well. However, no one responded to Mitsuhide's call.
Hashiba Hideyoshi received the first news the day after the incident. Hideyoshi immediately made peace with the Mōri clan, kept Nobunaga's death under wraps, and returned to the Kinai region with an ultra-fast, forced march known as Chūgoku Ōgaeshi (the Great Return from the Chugoku Region). After returning in about a week with an army of nearly 30,000 troops for a total distance of 200 km, Hideyoshi joined forces with Niwa Nagahide and Oda Nobutaka in Osaka and headed for Kyoto. With this momentum, Hideyoshi defeated Mitsuhide in the Battle of Yamazaki. While on the run, Mitsuhide was killed as a victim of an ochimushagari.
The Kiyosu Conference was then held to determine the successor to the Oda clan, and four vassals of the Oda clan, Shibata Katsuie, Niwa Nagahide, Ikeda Tsuneoki, and Hashiba Hideyoshi, attended the conference. Three names were mentioned as possible successors: Nobukatsu, the second son; Nobutaka, the third son; and Hidenobu (Sanhōshi), Nobutada's eldest son, or Nobunaga's grandson, who was only three years old.
After defeating Mitsuhide, Hideyoshi also searched for Nobunaga's body, but it still could not be found. In October 1582, Hideyoshi held Nobunaga's funeral at Daitoku-ji Temple in Kyoto. In place of his missing body, Hideyoshi had a life-size wooden statue of Nobunaga cremated and put it in an urn in place of his ashes.
There is no doubt that what Nobunaga feared most when he prepared to die was not dying but what would happen after death: in other words, how his body would be treated. Nobunaga must have understood that if his body had fallen into Mitsuhide's hands, his severed head would surely have been gibbeted, and he would have been disgraced as a criminal and that Mitsuhide would use Nobunaga's death to justify his rebellion by making it public. In such a situation, Nobunaga had a few possible options. He would have the body burned so that it could not be identified as Nobunaga's, or he would have it buried so that Mitsuhide could not find it inside Honnō-ji, or he would have someone he trusted carry it out of Honnō-ji, even at the risk of being stolen by Mitsuhide on the way. There are several theories regarding the fact that no bodies were found in the burnt ruins of Honnō-ji. One theory is that Nobunaga could not be identified because the bodies were too badly damaged, another that there were too many burned bodies to identify, and a third that the fire was so intense that his body was completely consumed.
There are also several stories that Nobunaga's body and head were carried out from Honnō-ji. There are a number of tombs in various parts of Japan that are said to be Nobunaga's, but there is no evidence that his body or ashes are buried in any of them.
Tokugawa Ieyasu heard the news in Hirakata, Osaka, but at the time, he had only a few companions with him. The Iga province track was also in danger of the Ochimusha-gari, or "Samurai hunters" gang. During the Sengoku period, particularly dangerous groups called "Ochimusha-gari" or "fallen warrior hunter" groups emerged. These groups consisted of peasant or Rōnin who dispossessed by war formed self-defense forces. However, in reality they often resorted to hunting and robbing defeated Samurais or soldiers during conflicts. These outlaw groups were particularly rampant on the route which Ieyasu took to return to Mikawa.
Ieyasu and his party, therefore, chose the shortest route back to the Mikawa province by crossing the Iga Province, which was different in many versions according to primary sources such as the records of Tokugawa Nikki or Mikawa Todai-Hon:
Regardless, whichever 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 are 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. There are 34 recorded Tokugawa vassals who survived this journey, such as Sakai Tadatsugu, Ii Naomasa, and 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 the 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.
It was reported by Edo period traditional records that Hattori Hanzō, a Tokugawa vassal from Iga, negotiated with Iga ninjas to hire them as guards along the way to avoid the ochimusha-gari. The local Koka-Ikki ninjas and Iga-Ikki ninjas under Hanzo who helped Ieyasu to travel into safety consisted of 300 Ninjas. Furthermore, Uejima Hidetomo, a researcher of Iga Ninja history, has stated there is research which revealed that Hattori Yasuji, one of the ninjas who accompanied Ieyasu on his journey in Iga province, also served as a bodyguard and espionage officer under Muromachi Shogun Ashikaga Yoshiaki.
However, a modern scholar such as Tatsuo Fujita doubted the credibility of Hattori Hattori Hanzō's ninja army theory, since it was first appeared in Iga-sha yuishogaki record which circulated in Edo period during the rule of Shogun Tokugawa Yoshimune. During his rule, Yoshimune were known for establishing the Oniwaban secret police institution whose members hailed from the confederation clans of Koka and Iga. It has been argued that the circulation of the myth about Hattori Hanzō ninja army helping Ieyasu was created as propaganda to increase the prestige of the Iga and Koka clan confederations in Tokugawa Shogunate.
On the other hand, Chaya Shirōjirō, a wealthy merchant in Kyoto, wrote that he went ahead and gave silver coins to local people and asked them to guide and escort the group, which is highly likely to be true since it also appears in Jesuit historical documents of the same period. However, the existence of Chaya Shirōjirō during this period itself is also doubted by historians, since it was recorded that Shirōjirō was born in 1600, so it was unlikely he existed during Ieyasu's travels in Iga province in 1582.
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.
Several theories regarding the motivation:
Thus, these stories were largely deemed by historians as unreliable, including the story of Mitsuhide betrayal from "Akechi-gunki" and "Kōyō Gunkan".
Other new theories from 20th century historians which involve the Ashikaga Shogunate also emerged:
The mastermind theory that someone behind the incident manipulated Mitsuhide Akechi to carry out Nobunaga's assassination is surprisingly new and has emerged since the 1990s. It all started when the well-known medieval historian 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.
There are several theories about the collaborator of Mitsuhide's act in Honnō-ji:
In the 2010s, a Shikoku theory was proposed that Mitsuhide, who valued his relationship with Chōsokabe Motochika, rose up to avoid Nobunaga's attack on Shikoku. Mitsuhide was entrusted by Nobunaga to negotiate with Chōsokabe, and the Akechi family and Chōsokabe had deep ties in relation to marriage. In 2020, NHK aired a program called "Honnoji Incident Summit 2020". Seven historians debated various theories, with the "Shikoku theory" garnering the most support.