The Battle of Okehazama — 25,000 vs 2,000: Why Did the Greatest Upset of the Sengoku Era Happen?

The 19th day of the 5th month, 1560 (Eiroku 3) | Okehazama, Owari Province

The Battle in Three Lines

• Imagawa Yoshimoto, who ruled Suruga, Tōtōmi, and Mikawa, invaded Owari with a great army of about 20,000.
• Oda Nobunaga of Owari struck the Imagawa headquarters with only about 2,000 troops and slew Yoshimoto.
• This victory became the starting point of Nobunaga’s drive to unify the realm, transforming the balance of power of the Sengoku era.

The Mainstream View — A Textbook-Based Explanation

Why the Battle Happened

Imagawa Yoshimoto ruled the three provinces of Suruga, Tōtōmi, and Mikawa and was called “the Greatest Bowman of the Tōkaidō,” one of the foremost powers of the Sengoku era. “Kaidō” refers to the Tōkaidō, and “bowman” means a warrior and, by extension, a daimyō who holds a province. Yoshimoto excelled at governing his domain, adding twenty-one articles to the “Imagawa Kana Mokuroku,” the oldest provincial law code in eastern Japan, established by his father Ujichika. He further advanced excellent administrative reforms, including the protection of commerce, the control of distribution, and the strengthening of his retainer band through the yorioya-yoriko (patron-client) system.

Oda Nobunaga, on the other hand, was a young daimyō who had only just succeeded to the headship and could not yet even unify the single province of Owari. Since the time of his father Oda Nobuhide, his house had carried on a generational struggle with the Imagawa over control of eastern Owari. Nobuhide at one point held power enough to threaten Imagawa-held Mikawa, but after his death the Oda house suffered from internal strife and decline.

The purpose of Yoshimoto’s invasion of Owari with a great army has long been debated. From the Edo period, the march-on-Kyoto theory—that he aimed to advance on the capital and command the realm—was held to be the established view, but recent research has rejected it. The historian Ōishi Yasufumi holds that no primary source exists showing that Yoshimoto was heading for Kyoto, and he organizes the non-march theory as follows:

• He aimed to establish control over eastern Owari.
• Pressure to stabilize his control over Mikawa.
• A military action aimed at territorial expansion.
• Seizing the Ise Bay trade route linking eastern and western Japan.
• Recovery of former territory taken by Oda Nobuhide.
• Intervention in the struggle for supremacy within the Oda house.

Ōishi points out that several of these purposes likely overlapped. In any case, the prevailing view today is that Yoshimoto was not heading for the capital for the sake of “seizing the realm,” but that his true aim was to consolidate his power in the Tōkai region.

The Course of the Battle

In the 5th month of 1560 (Eiroku 3), Imagawa Yoshimoto set out from Sunpu leading a great army. The vanguard was assigned to Matsudaira Motoyasu (later Tokugawa Ieyasu), who captured the Oda-held forts of Marune and Washizu. The opening engagements began with an overwhelming Imagawa victory.

On the night of the 18th day of the 5th month, Matsudaira Motoyasu succeeded in delivering provisions into the Imagawa frontline base of Ōdaka Castle. Ōdaka Castle was surrounded by Oda forts, and breaking through the enemy lines to bring in supplies was an extremely dangerous task, but the nineteen-year-old Motoyasu accomplished it splendidly. Ironically, the fateful battle came immediately after this success.

In the predawn of the 19th day, receiving word that both Marune and Washizu forts had fallen, Nobunaga performed the kōwakamai dance “Atsumori” at Kiyosu Castle before setting out. According to the “Shinchō Kōki,” Nobunaga dashed out of Kiyosu Castle with only six mounted attendants. He held no war council with his senior retainers and departed without conveying any details of his plan.

After praying for victory at Atsuta Shrine, Nobunaga moved through Zenshōji Fort to Nakajima Fort. Leading about 2,000 to 3,000 of his own troops, he headed toward the Imagawa headquarters. At this time, Nobunaga is said to have told his senior retainers: “The enemy is exhausted from night marching, delivering provisions, and attacking Marune and Washizu forts. We are fresh troops. If we strike, we can break them easily.”

At the same time, Yoshimoto’s main force departed Kutsukake Castle and advanced toward the Okehazama area, and around midday on the 19th it was resting men and horses on Okehazama-yama (or the area called Dengaku-hazama). It is also said that the Imagawa army was holding a banquet to celebrate its opening victory, but this is highly likely a later embellishment from works such as the “Hōan Shinchō-ki.”

Just then, a violent thunderstorm poured down. This downpour is said to have concealed the approach of Nobunaga’s army. When the rain stopped, Nobunaga took up his spear and ordered the charge: “Attack!” The Oda army broke through the Imagawa vanguard in a single rush and, carried by that momentum, poured into Yoshimoto’s headquarters.

Yoshimoto at first tried to retreat, guarded by 300 mounted hatamoto, but the Oda pursuit gradually stripped away the troops around him, and at last his mounted guards were overtaken. The first to set a spear on him was Hattori Koheita (Kazutada). But Yoshimoto counterattacked, cutting Koheita’s knee and putting him out of the fight. Mōri Shinsuke (Yoshikatsu), who rushed in there, grappled with Yoshimoto and finally took his head. Yoshimoto was 42. Sources such as the “Mizuno Katsunari Oboegaki” report that in his final moment Yoshimoto resisted by biting off one of Mōri’s fingers.

The Aftermath of the Battle

Yoshimoto’s death transformed the balance of power of the Sengoku era. The Imagawa house declined rapidly under his heir Ujizane, and in 1568 (Eiroku 11) it lost its home province to Takeda Shingen’s invasion of Suruga, so that the Imagawa house effectively perished as a Sengoku daimyō.

When Matsudaira Motoyasu received word of Yoshimoto’s death from his uncle Mizuno Nobumoto, he entered his family temple of Daiju-ji in Okazaki, Mikawa Province, and on the 23rd day of the 5th month entered Okazaki Castle for the first time in about eleven years. Thereafter he became independent of the Imagawa house, unified Mikawa, and in 1562 (Eiroku 5) concluded the Kiyosu Alliance with Nobunaga. Through this alliance, Nobunaga removed the threat to his east and advanced his pieces toward the conquest of Mino and, ultimately, the unification of the realm.

Multiple Theories — Exploring Possibilities from Various Angles

Theory 1: Surprise Attack or Frontal Assault?

The image of “Nobunaga’s surprise attack” is widely fixed in popular memory of the Battle of Okehazama, but this received view has been greatly shaken by recent research.

The flanking surprise-attack theory (old received view)

The theory that Nobunaga led his army on a detour and struck the rear of Yoshimoto’s headquarters while they rested off guard. This account appears in the “Hōan Shinchō-ki” written by the Confucian scholar Oze Hōan in the early Edo period, and because the “Nihon Senshi: Okehazama no Eki” (1911), compiled by the General Staff of the old Japanese Army in the Meiji era, adopted it, it long became the established view found even in textbooks. However, it has been pointed out that Hōan’s “Shinchō-ki,” while based on Ōta Gyūichi’s “Shinchō Kōki,” strongly has the character of a historical novel with added invention, and its value as a source is not necessarily high.

The frontal-assault theory (current mainstream view)

A theory that the historian Fujimoto Masayuki seriously proposed in 1993 in “Nobunaga no Sengoku Gunjigaku” and made decisive in his later “Okehazama no Tatakai: Nobunaga no Ketsudan, Yoshimoto no Gosan” (2010). He argued that a careful reading of the “Shinchō Kōki” shows Nobunaga charging the Imagawa army head-on, advancing east from Nakajima Fort, and that no description of a flanking surprise attack appears anywhere. In the historical scholarship of today, this frontal-assault theory has become almost the established view.

However, if it was a frontal assault, the question remains of “why the disparity in forces could be overturned.” It is thought to have been the result of several factors converging: poor visibility from the downpour, the dispersal of Imagawa forces, the thin guard around Yoshimoto’s headquarters, and chance good fortune.

The combined frontal-and-flanking theory; the separate-detachment theory

The “Matsudaira-ki,” compiled in the early Edo period, contains an account that Nobunaga divided his army into two, one unit attacking head-on and the other detouring to strike the rear. The writers Hashiba Akira and Ebata Hidesato have also proposed a new theory that a separate detachment attacked the Imagawa supply unit and that Yoshimoto’s headquarters was caught up in the resulting confusion. However, these theories have no decisive documentary basis.

The historian Watanabe Daimon points out: “The ‘Shinchō Kōki’ too was compiled in the early seventeenth century and is not a contemporary source. On a vast battlefield it was virtually impossible at the time to grasp accurately the movements of each and every commander and soldier. It cannot be denied that the ‘frontal-assault theory’ too may include Gyūichi’s own subjectivity.” Owing in part to the limits of the sources, the truth of the battle is still not completely clarified.

Theory 2: Yoshimoto’s Purpose in Marching — Advance on Kyoto, or Territorial Expansion?

The march-on-Kyoto theory (old received view)

The theory that Yoshimoto, of a distinguished lineage connected to the Ashikaga shogunal house, aimed to advance on the capital to command the realm in place of the weakened Muromachi shogunate. This theory has often been adopted in dramas and novels. The novels of Shiba Ryōtarō are also based on it.

The non-march theory (current leading view)

In a recent work, Ōishi Yasufumi holds the march-on-Kyoto theory to be hard to sustain and classifies the non-march theory into six: establishing control over Owari, stabilizing control over Mikawa, territorial expansion, seizing the Ise Bay trade route, recovering former territory taken by Oda Nobuhide, and intervening in the struggle for supremacy within the Oda house. Ōishi argues that “it is highly likely that several of these were simultaneously his motives.”

Even supposing Yoshimoto were aiming for the capital, beyond defeating the Oda still stood many enemies—the Saitō clan of Mino, the Azai and Rokkaku of Ōmi, and others. Considering the distance to Kyoto, it is natural to see his realistic operational objective as the consolidation of his footing in the Tōkai region.

Theory 3: Was the Imagawa Army Really 25,000 Strong?

The strength of the Imagawa army has often been given as “25,000” ever since the “Nihon Senshi: Okehazama no Eki” (1911), but in fact it differs greatly by source.

• “Shinchō Kōki” — about 40,000 (or “some 40,000”).
• “Hōan Shinchō-ki” — about 25,000.
• “Mikawa Monogatari” — about 45,000.
• “Kōyō Gunkan” — about 20,000.

Watanabe Daimon points out that, considering the mobilization capacity and supply conditions of the time, the actual number was likely around 10,000 to 20,000. More importantly, the Imagawa army was deployed dispersed among several castles and bases. The troops guarding Yoshimoto’s headquarters at Okehazama are said to have numbered about 5,000 to 6,000. The Oda army, meanwhile, was about 2,000. Seen in terms of the ratio of headquarters to headquarters, the disparity may not necessarily have been tenfold.

Still, the fact that the Oda army overturned an overwhelming disparity of forces does not change. The structure of “the inferior side concentrating its attack on the enemy’s strongest unit, the headquarters, and killing the supreme commander” is an extremely rare case even in Sengoku history.

Theory 4: Was Yoshimoto Really Off Guard?

It has long been said that Yoshimoto held a banquet in the Okehazama hollow (Dengaku-hazama) and was attacked while off guard. But it is considered unnatural for Yoshimoto, known as a skilled commander, to deliberately deploy in a hollow with poor visibility, and in recent years the theory that he placed his headquarters on the hilly “Okehazama-yama” has become leading.

Ōkubo Tadataka’s “Mikawa Monogatari” contains an account that Yoshimoto had confirmed the Oda forces coming toward Okehazama-yama and had strengthened his defenses to the northwest. This suggests the possibility that, in the perception of contemporaries, the Imagawa were not thought to have been completely off guard and taken by surprise. The image of “having his head taken in the midst of a banquet” is very likely to have had later embellishment added.

As for the exact place where Yoshimoto was killed, Imagawa-side material gives “Dengaku-kubo.” In the record of the 33rd memorial of Yoshimoto’s strategist Taigen Sessai, held in 1587 (Tenshō 15)—twenty-seven years after the Battle of Okehazama—it is recorded that on the 19th day of the 5th month, Yoshimoto was struck down in a single battle at Dengaku-kubo in Owari. “Dengaku-kubo” survives as the place name “Dengaku-ga-kubo” in present-day Kutsukake-chō, Toyoake City.

Two sites are still transmitted as the old battlefield where Yoshimoto was killed: “Okehazama Old Battlefield Park” in Midori Ward, Nagoya City, and “Okehazama Old Battlefield Legendary Site” in Toyoake City, and each city continues to preserve and commemorate its historic site.

Theory 5: Was Yanada Masatsuna Really “First in Merit”?

After the Battle of Okehazama, it is said that in distributing rewards, Nobunaga ranked first in merit not Mōri Shinsuke, who took Yoshimoto’s head, but Yanada Masatsuna, who reported the Imagawa army’s position. This anecdote is widely known as an episode showing Nobunaga to be an innovative figure who valued “the importance of information.” It was also impressively depicted in Shiba Ryōtarō’s novel “Kunitori Monogatari.”

However, this “first in merit” story does not appear in the “Shinchō Kōki.” It is found only in later sources such as the “Hōan Shinchō-ki,” “Mikawa Go-Fudoki,” and “Buke Jiki.” In fact, no letter of commendation from Nobunaga survives for the victorious Oda house (whereas such letters remain on the side of the defeated Imagawa house).

What can be confirmed from the sources is only the fact that, after the Battle of Okehazama, Kutsukake Castle, which had belonged to the Imagawa, became Yanada Masatsuna’s holding. That he performed a feat worthy of receiving Kutsukake is certain, but what kind of feat it was has not been determined. The concrete anecdote that he “conveyed the position of Yoshimoto’s headquarters” is now considered highly likely to be a later invention.

Theory 6: Is the “Effeminate, Court-Affected Warlord” Image True? — A Reassessment of Imagawa Yoshimoto

The image of Yoshimoto has long been fixed as “an effeminate, court-affected warlord, with whitened face and blackened teeth, riding in a palanquin.” But recent research has greatly overturned this image.

First, the talk of blackened teeth, painted eyebrows, and light makeup appears only from the mid-Edo period onward; there is no description in contemporary primary sources, and it is highly likely a later invention. Even if it were true, it was a grooming that indicated a family rank of shugo daimyō or above, and for a warrior heading to the battlefield to wear makeup was also a custom of the time.

Riding in a palanquin is no proof of effeminacy either. As a branch line of the Ashikaga, the Imagawa held a high family rank called one of the “Twenty-One Yakata of the Muromachi” and were specially permitted to ride in palanquins. Ōishi Yasufumi points out that in Owari only the Shiba clan—shugo and likewise an Ashikaga branch line—were qualified to ride in palanquins, and that Yoshimoto’s advancing by palanquin was a political performance to show the people of Owari, visually, the gap in family rank with the Oda. Incidentally, the “Shinchō Kōki” records that Yoshimoto, retreating from Okehazama-yama, was “on horseback,” so it is also clear that he was not unable to ride.

His military reputation is also high. Asakura Sōteki, a senior retainer of the Echizen Asakura, in his “Asakura Sōteki Waki” (contained in the “Zokuzoku Gunsho Ruijū”), ranked Yoshimoto alongside Takeda Harunobu (Shingen), Oda Nobunaga, Miyoshi Nagayoshi, Nagao Kagetora (Uesugi Kenshin), and Mōri Motonari, calling him “a holder of a province, a master at handling men, a person who should be called a good model.” This is an assessment by a contemporary as one of the foremost commanders of the Sengoku era.

In domestic administration too, he advanced excellent reforms: enacting the twenty-one additional articles of the Imagawa Kana Mokuroku, protecting commerce, controlling distribution, and strengthening his retainer band through the patron-client system. He further invited many cultured figures and court nobles from Kyoto and raised Sunpu into one of the “three great Sengoku cultures,” alongside the Ōuchi of Yamaguchi and the Asakura of Ichijōdani in Echizen.

The image of an “effeminate, court-affected warlord” is highly likely to have been a later label, reasoned backward from the result of his being the loser defeated by Nobunaga at Okehazama. The current assessment is that Yoshimoto was, rather, one of the foremost wise rulers of the Sengoku era.

Viewed Strategically

What deserves attention in this battle is the thoroughness of Nobunaga’s “information control” and the judgment with which he discerned the “now or never” timing.

Nobunaga held no war council on the eve of the battle. According to the “Shinchō Kōki,” while his retainers urged defending the castle, Nobunaga only made idle talk and, without touching on the battle at all, said, “The night has grown late; all of you withdraw and rest,” and retired to the interior. His senior retainers are recorded as having gone down from the castle scoffing, “They say that when one’s luck is about to run out, even the mirror of wisdom clouds over—this is exactly that.”

On the day itself, too, he dashed out of Kiyosu Castle with only six mounted men. This action, reckless at first glance, becomes rational if interpreted as a measure to prevent the leakage of operational information. At the time, when defections from the Oda side to the Imagawa were occurring one after another, holding a war council carried the risk of the plan being laid bare to the enemy.

Another point of note is that Nobunaga read the state of the Imagawa army accurately. He instructed his senior retainers: “The enemy is exhausted from night marching, delivering provisions, and attacking forts. We are fresh troops. We can break them easily.” This was not mere bravado but a rational assessment of the situation, having discerned the enemy’s condition.

The conditions for the heavily outnumbered side to win are cited as “dispersal of the enemy,” “an advantage in information,” “use of weather and terrain,” and “a direct strike against the commander,” and at the Battle of Okehazama all of these elements were present. The Imagawa army was dispersed among several bases, and the headquarters troops numbered about 5,000 to 6,000. The downpour concealed the Oda army’s approach, and Nobunaga’s army directly attacked Yoshimoto’s headquarters.

Of course, not everything went according to calculation. It is doubtful whether Nobunaga had grasped the exact position of Yoshimoto’s headquarters in advance, and that he was able, in the end, to charge into it owed much to chance. Even so, it can be said that the essence of this miraculous victory was Nobunaga’s judgment—deploying his troops in a position from which he could seize that “chance,” and ordering the charge with decisiveness.

Throughout the Sengoku era, examples of a Sengoku daimyō being killed on the battlefield are extremely few. Okehazama is one of those rare examples and became a decisive moment that greatly changed the flow of Sengoku history.

Famous Words and Sayings of This Battle

“A man’s span of fifty years, set against the heavens, is but a fleeting dream.”

A passage from the kōwakamai dance “Atsumori,” said to have been performed by Nobunaga at Kiyosu Castle before setting out for Okehazama. Its content: that the fifty years of human life are as fleeting as a dream when compared with the time of the heavens. It has been handed down as a phrase symbolizing the state of mind of Nobunaga, who set out with a resolve unafraid even of death in the face of an overwhelming disparity of forces. The “Shinchō Kōki” records it as: “A man’s span of fifty years, set against the heavens, is but a fleeting dream. Having once received life, is there anything that does not perish?”

— Source: kōwakamai “Atsumori” / Ōta Gyūichi, “Shinchō Kōki”

“The enemy has marched all night and is exhausted from delivering provisions and attacking forts. We are fresh troops; we can break them easily.”

(summarized from the opening volume of the “Shinchō Kōki”)

The instruction Nobunaga gave to the elders who remonstrated against his thrust into the enemy after he entered Nakajima Fort. It was a rational assessment of the situation that accurately read the exhaustion of the Imagawa army, an important statement showing that Nobunaga decided not out of mere recklessness but on the basis of situational analysis.

— Source: Ōta Gyūichi, “Shinchō Kōki”

“Fortune lies with Heaven. If the enemy attacks, fall back; if they withdraw, press on. Avoid individual contests for glory and always act in an organized manner.”

Words said to be the instruction Nobunaga gave his troops when ordering the charge. The directive to fight as an organization rather than compete for individual merit was an advanced idea by the standards of the Sengoku period. However, there is debate over how far this instruction can be traced back to a primary source.

— Source: “Shinchō Kōki” and other works

“A holder of a province, a master at handling men, a person who should be called a good model.”

Words by which Asakura Sōteki, a senior retainer of the Echizen Asakura, appraised Imagawa Yoshimoto in the “Asakura Sōteki Waki.” The meaning: “a person excellent at governing his domain, skilled at using men, who should be taken as a model for a Sengoku daimyō.” He placed Yoshimoto on the same level as Takeda Shingen, Oda Nobunaga, Uesugi Kenshin, and Mōri Motonari, showing that the assessment of Yoshimoto’s ability in his own time was extremely high.

— Source: “Asakura Sōteki Waki” (contained in the “Zokuzoku Gunsho Ruijū”)

Anecdotes and Episodes

A Departure with Only Six Horsemen

According to the “Shinchō Kōki,” when Nobunaga set out from Kiyosu Castle in the predawn of the 19th day of the 5th month, his attendants were only six horsemen. Leaving the castle, Nobunaga galloped to Atsuta Shrine and gathered his troops there. The leading view is that he set out without holding any war council with his senior retainers in order to prevent the leakage of operational information. At the time it was highly likely that there were informers connected to the Imagawa even within the Oda house, and Nobunaga’s caution is evident.

At the war council on the eve of the battle, while his retainers argued for defending the castle, Nobunaga only made idle chatter and did not touch on the battle at all. At the sight of Nobunaga saying “The night has grown late; all of you withdraw and rest” and retiring to the interior, his senior retainers are said to have gone down from the castle scoffing, “They say that when one’s luck runs out, even the mirror of wisdom clouds over—this is exactly that.”

— Source: Ōta Gyūichi, “Shinchō Kōki”

Yoshimoto’s Final Moment — Drawing His Sword to Fight, Biting Off Mōri’s Finger

Imagawa Yoshimoto is said to have drawn his own sword and fought back just before he was killed. He cut the knee of Hattori Koheita (Kazutada), the first to set a spear on him, putting him out of the fight, and when Mōri Shinsuke (Yoshikatsu), who rushed in, grappled with him, Yoshimoto bit off Shinsuke’s left finger and resisted to the end. This anecdote is recorded in the “Mizuno Katsunari Oboegaki,” “Owari-shi,” “Taikōki,” and others. It is also said that Yoshimoto’s head, severed from his body, still held Mōri’s finger in its mouth.

Contrary to the image of an “effeminate, court-affected warlord,” Yoshimoto fought to the last as a warrior. As Asakura Sōteki appraised him as “a master at handling men,” Yoshimoto was one of the foremost powers of the Sengoku era.

— Source: Ōta Gyūichi, “Shinchō Kōki”; “Mizuno Katsunari Oboegaki”; “Owari-shi”; and others

→ For details, see the warlord article “Imagawa Yoshimoto.”

Ieyasu’s Provisioning — A Desperate Run to Ōdaka Castle

The day before the battle, Matsudaira Motoyasu (later Tokugawa Ieyasu) succeeded, as the Imagawa vanguard, in delivering provisions to Ōdaka Castle. Ōdaka Castle was surrounded by the Oda, and delivering provisions through the enemy lines was an extremely dangerous task. The nineteen-year-old Motoyasu accomplished this difficult duty and raised his martial fame. Ironically, because Yoshimoto was killed immediately after the success of this provisioning, Motoyasu met the turning point of becoming independent of the Imagawa house.

When Motoyasu received word of Yoshimoto’s death from his uncle Mizuno Nobumoto, he did not move at once but is said to have first spent time confirming the information. His cautious character was there from his youth. After confirming it, he entered his family temple of Daiju-ji in Okazaki, and then on the 23rd day of the 5th month entered Okazaki Castle for the first time in about eleven years. He took his first step toward independence from the Imagawa house.

— Source: National Archives of Japan, “Tokugawa Ieyasu: His Life Seen Through the Shogunal House Library”; Shiba Hiroyuki, “Tokugawa Ieyasu: From Border Lord to Ruler of the Realm”

The Downpour That Took His Side — Chance or Inevitability?

When Nobunaga’s army approached the Imagawa headquarters, a violent thunderstorm suddenly poured down. There is also a record that a camphor tree at the base of a pine on Kutsukake Pass was felled by the strong wind, suggesting it was quite a tempest. This downpour is said to have blocked the Imagawa army’s view and kept them from noticing the Oda army’s approach. Just after the rain stopped, Nobunaga ordered the charge.

It is an episode showing Nobunaga’s “strength of fortune” in making the weather his ally, but it can also be said that the essence was his judgment in deploying his troops in a position where he could make use of the chance rain. Had he not advanced his troops from Nakajima Fort toward Yoshimoto’s headquarters, a charge under cover of the downpour would have been impossible. Nobunaga’s true worth lay in never neglecting “the preparation to seize fortune.”

— Source: Ōta Gyūichi, “Shinchō Kōki”

The Death of Taigen Sessai and the Imagawa Clan’s Strategic Eye

Taigen Sessai, Yoshimoto’s strategist, had passed away in 1555 (Kōji 1), three years before Okehazama. Sessai served as Yoshimoto’s tutor from his childhood and later single-handedly bore the Imagawa house’s strategic planning as a strategist and diplomat. The conclusion of the “Kō-Sō-Sun Triple Alliance” with the Takeda and Hōjō is also counted among Sessai’s achievements.

Some historical researchers connect Yoshimoto’s carelessness and misjudgment at Okehazama with a decline in the Imagawa house’s strategic eye in the five years since Sessai’s death. The conjecture is that, had Sessai been alive, Yoshimoto might have avoided marching out alone or leaving his headquarters guard thin. It is of course an “if” argument with no documentary basis, but it is a thought-provoking perspective.

— Source: Kuroda Motoki, ed., “Imagawa Yoshimoto and His Times,” Ebisu Kōshō Shuppan, 2019

Two Old Battlefields — The Nagoya City Theory and the Toyoake City Theory

Two sites are transmitted as the exact place where Yoshimoto was killed: “Okehazama Old Battlefield Park” in Midori Ward, Nagoya City, and “Okehazama Old Battlefield Legendary Site” in Toyoake City. Each city has set up stone monuments and explanatory boards and still claims to be the “true old battlefield.” Which is correct has not been settled, and this itself embodies “there are multiple theories.”

Imagawa-side material gives “Dengaku-kubo,” and the record of Taigen Sessai’s 33rd memorial (1587) likewise records that on the 19th day of the 5th month Yoshimoto was struck down at Dengaku-kubo in Owari. Because “Dengaku-kubo” survives as the place name “Dengaku-ga-kubo” in present-day Kutsukake-chō, Toyoake City, the Toyoake City theory seems to have the edge; but in the Dengaku-tsubo area where Okehazama Old Battlefield Park stands, a grave monument carved with “tomb of the Suruga lord” has been unearthed, so the Nagoya City side also has strong grounds. Because the two cities are about one kilometer apart, many fans visit both.

Battle of Okehazama Timeline

Period	Event
Kōji 1 (1555)	Yoshimoto’s strategist Taigen Sessai dies. The Imagawa house loses its strategic planner.
Eiroku 2 (1559)	Nobunaga nearly achieves the unification of Owari. Yoshimoto secures Narumi, Ōdaka, and Kutsukake castles in eastern Owari.
Early 5th month, 1560	Imagawa Yoshimoto sets out from Sunpu leading a great army. Matsudaira Motoyasu is assigned to the vanguard.
5th month, 17th day	The Imagawa vanguard reaches eastern Owari. Yoshimoto’s main force enters Kutsukake Castle.
5th month, 18th day	War council at Kiyosu Castle. The retainers urge defending the castle, but Nobunaga gives no concrete orders and retires to the interior.
Night of 5th month, 18th day	Matsudaira Motoyasu succeeds in delivering provisions to Ōdaka Castle.
Predawn, 5th month, 19th day	Marune and Washizu forts are captured by the Imagawa army. Nobunaga performs “Atsumori” at Kiyosu Castle and sets out with only six horsemen.
Early morning, 5th month, 19th day	Nobunaga prays for victory at Atsuta Shrine. Moves through Zenshōji Fort to Nakajima Fort.
Morning, 5th month, 19th day	A decoy unit of 300 men under Sassa Hayato-no-shō and Senshū Shirō attacks the Imagawa army and is defeated (Sassa Hayato is killed).
Around midday, 5th month, 19th day	Yoshimoto’s main force departs Kutsukake Castle and rests at Okehazama-yama. A violent thunderstorm falls. Just after the rain stops, Nobunaga orders the charge.
Afternoon, 5th month, 19th day	Imagawa Yoshimoto is killed. Hattori Koheita is first spear, Mōri Shinsuke takes the head. The Imagawa army collapses entirely.
Evening, 5th month, 19th day	Mizuno Nobumoto conveys word of Yoshimoto’s death to Matsudaira Motoyasu. Motoyasu goes to Daiju-ji.
5th month, 23rd day	Matsudaira Motoyasu enters Okazaki Castle for the first time in about eleven years. His first step toward independence from the Imagawa.
After the battle	The Imagawa house declines rapidly. Matsudaira Motoyasu sets about unifying Mikawa.
Eiroku 5 (1562)	Nobunaga and Motoyasu conclude the Kiyosu Alliance. A relationship of alliance spanning the next twenty years begins.
Eiroku 11 (1568)	Takeda Shingen’s invasion of Suruga. The Imagawa house effectively perishes as a Sengoku daimyō.

* Dates are in the old (lunar) calendar. Times are approximate.

Battle of Okehazama: Key Figures of Both Armies

The Oda Army (about 2,000–3,000)

Role	Person	Summary
Supreme commander	Oda Nobunaga	Age 27. Struck the Imagawa headquarters with a small force and killed Yoshimoto.
First spear	Hattori Koheita (Kazutada)	Set the first spear on Yoshimoto, but was struck back and had his knee cut, putting him out of the fight.
Killed the commander	Mōri Shinsuke (Yoshikatsu)	Saved Koheita from his plight, grappled with Yoshimoto, and took his head. Had his finger bitten off.
Man of merit	Yanada Masatsuna	Received Kutsukake Castle after the battle. Said to be “first in merit,” but the content of his feat is unknown.
Fort commander	Sakuma Nobumori	Defended Zenshōji Fort. Supported Nobunaga’s advance.
Decoy unit	Sassa Hayato-no-shō and Senshū Shirō	Led a decoy unit of 300 men in an attack on the Imagawa army and were defeated (Sassa Hayato killed).

The Imagawa Army (about 10,000–20,000; headquarters 5,000–6,000)

Role	Person	Summary
Supreme commander	Imagawa Yoshimoto	Age 42. “The Greatest Bowman of the Tōkaidō.” Drew his sword and fought back, but was killed.
Vanguard	Matsudaira Motoyasu	Age 19 (later Tokugawa Ieyasu). Succeeded in delivering provisions to Ōdaka Castle. Became independent after the battle.
Vanguard commander	Matsui Munenobu	One of the Imagawa army’s vanguard commanders. Killed in the battle. His descendants erected the Okehazama memorial stele.
Attack on Washizu Fort	Asahina Yasutomo	An Imagawa senior retainer. Captured Washizu Fort.
Defense of Narumi Castle	Okabe Motonobu	Held Narumi Castle to the death even after Yoshimoto’s death. Said to have opened the castle in exchange for Yoshimoto’s head.
(Deceased)	Taigen Sessai	Yoshimoto’s strategist and tutor. Died five years before Okehazama (1555). Some see Sessai’s death as having brought about a decline in the Imagawa house’s strategic eye.

Related Historic Site Map / Travel Model Course

Related Historic Site Map — Battle of Okehazama

Spots on the Map:

• Okehazama Old Battlefield Park (battlefield) — The decisive site where Nobunaga killed Yoshimoto (Nagoya City theory).
• Okehazama Old Battlefield Legendary Site (battlefield) — The place of Yoshimoto’s death (Toyoake City theory).
• Grave of Imagawa Yoshimoto (Daishō-ji) (grave/monument) — Yoshimoto’s burial site.
• Kiyosu Castle (castle) — Nobunaga’s home castle. The place of his departure.
• Atsuta Shrine (shrine/temple) — The shrine where Nobunaga prayed for victory.
• Zenshōji Fort ruins (fort) — The fort from which Nobunaga finally sortied.
• Narumi Castle ruins (castle) — An Imagawa frontline base.
• Ōdaka Castle ruins (castle) — The castle where Matsudaira Motoyasu (Ieyasu) succeeded in delivering provisions.

* The map is a reference display based on modern roads. It differs from the roads and terrain of the Sengoku period.

📍 View the route on Google Maps (switchable between car/train)

Travel Model Course — Battle of Okehazama — A One-Day Course to Relive Nobunaga’s Great Reversal

Preconditions

• Required time: about 4–5 hours (by car).
• Walking pace: about 4 km/h; stay at each spot: 20–40 minutes.
• Starting point: Kiyosu Castle.

Model Course

① Kiyosu Castle (stay: about 30 min)
The home castle where Nobunaga performed “Atsumori” and set out. Start from Nobunaga’s point of departure.
– By car: about 5 min from the Kiyosu exit of the Nagoya Expressway.

② Atsuta Shrine (stay: about 30 min)
The place where Nobunaga prayed for victory. The grounds are spacious with many points of interest.
– By car: about 20 min from Kiyosu Castle.

③ Zenshōji Fort ruins (stay: about 20 min)
The fort from which Nobunaga finally sortied. The surrounding terrain gives a feel for the spatial relations of the battlefield.
– By car: about 20 min from Atsuta Shrine.

④ Okehazama Old Battlefield Park (stay: about 40 min)
The old battlefield site on the Nagoya City side. There are explanatory monuments of the battle and statues of Nobunaga and Yoshimoto.
– By car: about 10 min from the Zenshōji Fort ruins.

⑤ Okehazama Old Battlefield Legendary Site / Grave of Imagawa Yoshimoto (stay: about 30 min)
The old battlefield site on the Toyoake City side. Yoshimoto’s grave is here.
– By car: about 5 min from the Old Battlefield Park.

Arrangements by Type of Traveler

• For the strong of leg: A complete course including the Imagawa frontline bases, touring the Ōdaka Castle and Narumi Castle ruins as well.
• For the leisurely: A half-day course of two spots, Atsuta Shrine and Okehazama Old Battlefield Park.

* This plan is a reference model based on general travel speeds and stay times. Facility hours, transit schedules, and crowd conditions vary by season and day of the week. When going out, please check the latest information on the official websites of each facility and transit operator.

* Entry and admission fees are reference prices as of the time of writing. They may have changed.

* For climbing to mountain castle ruins, please make a reasonable plan according to weather and your physical condition.

Related Articles

Battle Articles

• Battle of Inabayama Castle (1567) — Seven years after Okehazama, the decisive battle in which Nobunaga conquered Mino.
• Battle of Anegawa (1570) — A new conflict brought on by Nobunaga’s rise that began at Okehazama.
• Battle of Mikatagahara (1572) — Ieyasu, freed at Okehazama, clashes with Shingen.

Warlord Articles

• Oda Nobunaga — Aimed at unifying the realm, with the victory at Okehazama as his starting point.
• Imagawa Yoshimoto — The defeated commander of Okehazama, called “the Greatest Bowman of the Tōkaidō.”
• Tokugawa Ieyasu — Became independent of the Imagawa at Okehazama and formed an alliance with Nobunaga.
• Taigen Sessai — Yoshimoto’s strategist. Died five years before Okehazama.
• Oda Nobuhide — Nobunaga’s father. Carried on a generational struggle with the Imagawa over eastern Owari.

References

Primary Sources

• Ōta Gyūichi, “Shinchō Kōki” — the most reliable record, by a retainer of Nobunaga.
• Ōkubo Tadataka, “Mikawa Monogatari” — contains the account that Yoshimoto had confirmed the Oda forces.
• “Asakura Sōteki Waki” (contained in the “Zokuzoku Gunsho Ruijū”) — appraises Yoshimoto as “a master at handling men.”
• The record of the 33rd memorial of Taigen Sessai (1587) — records the place of Yoshimoto’s death as “Dengaku-kubo.”

Academic Works

• Fujimoto Masayuki, “Okehazama no Tatakai: Nobunaga no Ketsudan, Yoshimoto no Gosan” (Yōsensha, 2010) — the definitive work of the frontal-assault theory.
• Fujimoto Masayuki, “Nobunaga no Sengoku Gunjigaku” (JICC Shuppankyoku, 1993) — the pioneering study that proposed the frontal-assault theory.
• Taniguchi Katsuhiro, “Nobunaga no Tenka Fubu e no Michi” (Yoshikawa Kōbunkan, 2006).
• Hirano Akio, “The Battle of Okehazama,” in “Nobunaga-gun no Kassen-shi 1560–1582” (supervised by the Nihonshi Shiryō Kenkyūkai, ed. Watanabe Daimon, Yoshikawa Kōbunkan, 2016).
• Ōishi Yasufumi, ed., “Series: Studies of Medieval Kantō Warriors, Vol. 27: Imagawa Yoshimoto” (Ebisu Kōshō Shuppan, 2019).
• Kuroda Motoki, ed., “Imagawa Yoshimoto and His Times” (Ebisu Kōshō Shuppan, Series: New Studies of Sengoku Daimyō 1, 2019).
• Watanabe Daimon, ed., “Tokugawa Ieyasu Kassen-roku: Poor at War or Skilled at War” (Seikaisha Shinsho).
• Shiba Hiroyuki, “Tokugawa Ieyasu: From Border Lord to Ruler of the Realm” (Heibonsha, From the Medieval to the Early Modern, 2017).

Published Papers

• Hasegawa Hiromichi, “The Intent of the Military Action of the 5th Month of Eiroku 3,” “Sengokushi Kenkyū” no. 35 (Yoshikawa Kōbunkan, 1998).
• Kubota Masaki, “A Reexamination of the Battle of Okehazama,” in “The Sengoku Daimyō Imagawa Clan and Domain Rule” (Yoshikawa Kōbunkan, 2005).
• Kuroda Hideo, “The Battle of Okehazama and the Kōyō Gunkan,” in “On the Sources of the Kōyō Gunkan: Takeda Shingen’s Vision of the State” (Azekura Shobō, 2015).
• Ogawa Yū, “The Imagawa Clan’s Designs on Mikawa and Owari and the Mizuno Family,” in “Ronshū: The Sengoku Daimyō Imagawa Clan” (ed. Sengokushi Kenkyūkai, Iwata Shoin, 2020).
• Muraoka Mikio, “A Verification of Oda Nobuhide’s Capture of Okazaki,” “Chūkyō Daigaku Bungaku Ronsō” no. 1 (Chūkyō University, 2015).

Public Institution Materials

• National Archives of Japan, “Tokugawa Ieyasu: His Life Seen Through the Shogunal House Library.”
• Okehazama Old Battlefield Preservation Society (Midori Ward, Nagoya City), official site.
• Toyoake City official tourism guide (Okehazama Old Battlefield Legendary Site).

* This article is composed on the basis of the sources, research works, and papers above, as well as multiple information sources on the web. There are points on which interpretations of history differ even among researchers, and established views may change with the discovery of new sources or the advance of research.