＜prologue＞
I started a blog called “The Baby Boomer Generation’s Miscellaneous Blog”（Dankai-sedai no garakutatyou:団塊世代の我楽多（がらくた）帳） in July 2018, about a year before I fully retired. More than six years have passed since then, and the number of articles has increased considerably.
So, in order to make them accessible to people who don’t understand Japanese, I decided to translate my past articles into English and publish them.
It may sound a bit exaggerated, but I would like to make this my life’s work.
It should be noted that haiku and waka （Japanese short fixed form poems） are quite difficult to translate into English, so some parts are written in Japanese.
If you are interested in haiku or waka and would like to know more, please read introductory or specialized books on haiku or waka written in English.
I also write many articles about the Japanese language. I would be happy if these inspire more people to want to learn Japanese.
my blog’s URL:団塊世代の我楽多（がらくた）帳 | 団塊世代が雑学や面白い話を発信しています
my X’s URL:団塊世代の我楽多帳（@historia49）さん / X
The Sengoku period is a time filled with mysteries and enigmas for history fans. One such mystery is the Battle of Okehazama.
This time, I’d like to consider the mystery of “Why was Oda Nobunaga victorious in the Battle of Okehazama?”
I’m also looking forward to seeing how the Battle of Okehazama will be portrayed in this year’s taiga drama, “Kirin ga Kuru.” Akechi Mitsuhide was thought to have been serving Asakura Yoshikage of Echizen at the time of the battle, and I’m interested to know how he viewed it. There is also a theory that Kinoshita Tōkichirō played an important role as a member of the Oda army.
1. What is the Battle of Okehazama?
The Battle of Okehazama is the most famous of the “Three Great Surprises of Japan.” These are three particularly famous or unusual battles from the Sengoku period: the Battle of Kawagoe Castle (1546), the Battle of Itsukushima (1555), and the Battle of Okehazama (1560).
The Battle of Okehazama was a surprise attack by Oda Nobunaga against Imagawa Yoshimoto, which took place at Okehazama in Owari Province on June 5, 1560. Oda Nobunaga was victorious, Imagawa Yoshimoto was killed, and the Imagawa clan was destroyed.
Around 1:00 p.m., heavy rain began to fall, obscuring visibility. Ota Gyuichi’s “Shincho-kōki” (Record of Nobunaga’s Chronicles) states that the rain “mixed with stones and water,” suggesting that it was hail. According to the Shincho-koki, Yoshimoto abandoned his palanquin and was surrounded by 300 guards. He attempted to retreat on horseback, but after repeated attacks he lost soldiers around him, and was finally caught up with and killed by Nobunaga’s horsemen.
With their commander-in-chief, Imagawa Yoshimoto, killed in battle, the Imagawa army lost their will to fight and fled.
2. Various theories about the reasons for Oda Nobunaga’s victory
However, the question remains as to why Imagawa Yoshimoto, the powerful Sengoku lord of Suruga Province who reigned over the Tokaido and boasted a powerful army of 25,000 men at the time, invaded eastern Owari Province and was so easily defeated by Oda Nobunaga, who led a small army in a surprise attack on the Imagawa headquarters.
(1) Imagawa Yoshimoto’s Overconfidence and Carelessness
Imagawa Yoshimoto was overconfident about his large army and underestimated Oda Nobunaga. He took a break at Okehazama, where he let his guard down while drinking and other activities, leading to his defeat.
It seems that Imagawa Yoshimoto, buoyed by his initial victories after capturing the Marune and Washizu forts, let his guard down.
Although the Imagawa forces totaled more than 20,000, Yoshimoto’s defense consisted of only 5,000 to 6,000 men, while Nobunaga, who launched the surprise attack on Yoshimoto’s headquarters, only had 2,000 to 3,000 men.
(2) The effects of bad weather and soldier fatigue from the initial battle
The sudden attack was accompanied by heavy hailstorms that obscured visibility, and the Imagawa soldiers were resting after the initial battle. This led to confusion and defeat, as they were unable to prepare for a counterattack.
(3) The topography of Okehazama caused the army’s formation to become disorganized.
(4) Nobunaga’s scouts accurately monitored the movements of Yoshimoto’s army and the location of his main camp.
(5) Kinoshita Tōkichirō (later Toyotomi Hideyoshi) had a “meticulous and well-planned plan to assassinate Imagawa Yoshimoto.”
This is the theory presented by Kato Hiroshi in his novel “The Blank Okehazama.” While (1) through (4) attribute the victory to the Imagawa army’s carelessness and Nobunaga’s superior abilities to assess the situation, strategize, and gather information, Kato Hiroshi’s theory asserts that Kinoshita Tōkichirō was the driving force behind the victory.
“The Blank Okehazama” argues that the Battle of Okehazama was not “Nobunaga’s miraculous surprise attack,” but rather “a diversionary tactic by Kinoshita Tōkichirō (a “mountain people”), mobilizing a large number of mountain people, and a well-planned assassination plan using highly trained hunting dogs at the surrender conference between Imagawa Yoshimoto’s side and the Oda side.” Kinoshita Tōkichirō seems to have been quite a strategist.
Indeed, even if Imagawa Yoshimoto had let his guard down, he would have had vassals providing heavy guards, so it is unlikely that he would have been killed so easily, so the author’s hypothesis is persuasive.
3. Kinoshita Tōkichirō’s “Meticulous and Well-Prepared Plan to Assassinate Imagawa Yoshimoto” (Details of the “Blank Okehazama” Theory)
(1) What are the “Mountain People”?
The “mountain people” were founded by Fujiwara Michitaka (older brother of Fujiwara Michinaga), regent and chancellor of the mid-Heian period. In the shadow of Fujiwara Michinaga’s success, Michitaka’s illegitimate son, Michimune, was driven out of Kyoto and lived in hiding in the Tanba mountains. They raised cattle and horses, and also engaged in irrigation and civil engineering.
Kinoshita Tōkichirō was the third generation of mountain people who had descended from the mountains and blended into the plains, mastering martial arts (blinding, stone throwing, how to start and preserve fire, how to handle horses, etc.) through group training. Maeno Shōemon and Hasegawa Koroku were fourth-generation members, and were well-versed in irrigation and civil engineering. They were skilled in combat that would put ninjas to shame, as well as in discreet information gathering and espionage.
According to Kato Hiroshi, Tōkichirō possessed the gift of intuitive visualization, able to visualize the structures and numbers of castles and forts with his eyes closed.
(2) Tōkichirō’s “Underground Operations”
He ordered Hasegawa Koroku, a mountain dweller, to divide the mountain dwellers into “Clown Group,” “Farmer Group,” and “Teahouse Owners and Live-in Servants” groups, and train each group accordingly.
The clowns were useful for espionage, and the farmers were not seen grazing their livestock. The teahouses were the mountain dwellers’ frontline bases, but their presence in these locations did not arouse suspicion.
(3) He advised Nobunaga to write a “Letter of Surrender to Imagawa Yoshimoto.”
In exchange for the humiliation of surrendering, Tōkichirō lured Imagawa Yoshimoto to a surrender meeting site unsuitable for battle, and he explained to Nobunaga that the actual assassination would be carried out by the mountain dwellers and their hounds (war dogs), while the credit for the assassination would be taken by Oda Nobunaga and his vassals, and he obtained Nobunaga’s approval.
(4) Mountain people offer sake and food to Imagawa retainers.
As if to celebrate the Imagawa’s victory, mountain people disguised as locals offer sake, rice cakes, and other food to the Imagawa retainers, lulling them into a false sense of security.
(5) Unleash hunting dogs at the surrender conference room to assassinate Imagawa Yoshimoto.
When the generals of both sides gathered at the surrender conference room in the Dengaku-Hasama area, Tōkichirō signaled with a dog whistle, and the mountain people hiding near the conference room unleashed their trained hunting dogs, which then bit into the throats of Imagawa Yoshimoto and his men.
The Oda generals had previously applied a foul-smelling liquid to their armor and faces to repel the hunting dogs, so the hunting dogs only attacked the Imagawa generals. As a result, Imagawa Yoshimoto was killed, the Imagawa forces were completely defeated, and the Oda side achieved a crushing victory.