A.  Early Clashes with the Imagawa

In addition to the battles against the Kiyosu and Iwakura factions, and his own brother, Nobunaga faced the threat of invasion from the powerful Imagawa clan of Suruga Province.  The Imagawa descended from the Muromachi bakufu in Kyōto.  Yoshimoto’s ancestor, Imagawa Norikuni, achieved victories for Ashikaga Takauji, garnering control of the provinces of Suruga and Tōtōmi in the early 1330’s.  Two battles known as the Genkō no Ran and the Engen no Ran occurred during this period.   The Imagawa clan had maintained their control of the Tōkai Region for generations, leading up to the Sengoku period.

Operating from Okazaki Castle in Mikawa, the Imagawa expanded their sphere of influence into Owari, most notably by an assault on Mizuno Nobumoto, lord of Ogawa Castle in 1554.  The Imagawa launched the plan by first attacking and capturing Shigehara Castle.  Next, the invading forces built Muraki fortress as a bridgehead to prepare for the assault. Ogawa Castle stood at the border between the Oda and Imagawa territories to the south of Nagoya.  Nobumoto had loyally supported the Oda for over ten years.  If the castle fell, the Imagawa could sweep from the Chita District to the southern part of the Aichi District.  The situation worsened for the Oda when the lord of Teramoto Castle betrayed the Oda in favor of the Imagawa, blocking the road between Nagoya and Ogawa castles. 

Nobunaga wanted to protect his ally in Ogawa, but his struggle with the Kiyosu faction remained the focus of his attention.  He knew that if he departed Nagoya, the Kiyosu faction would seize the opportunity to attack.  To confront this threat, he requested support from his father-in-law, Saitō Dōsan.  Dōsan responded by sending over one thousand men under the command of Andō Morinari to protect Nagoya Castle, freeing Nobunaga to engage the Imagawa by leveraging the alliance between the Oda and the Saitō.

Nobunaga set out with his troops from Nagoya.  Oda Nobumitsu from Moriyama Castle joined the contingent.  Along the route to Ogawa lay Narumi and Ōdaka castles, defended by hostile forces.  Choosing to bypass these positions, Nobunaga left the town of Atsuta by boat and crossed Ise Bay in a blustery wind, soon arriving on the western shore of the Chita Peninsula.  Nobunaga joined troops from the Mizuno clan to launch at dawn a three-pronged assault on the Muraki fortress from the south.  The Mizuno men attacked the front gate to the castle on the east, Nobumitsu led men against the back gate on the west, and Nobunaga’s men fired arquebuses over a large moat toward the entrance on the south side of the fort.  Within a short time, the invaders broke through the perimeter walls, and engaged the defenders on the grounds of the fort.  Scores of peasant militia died on both sides in a nine-hour battle resulting in surrender of the fort at dusk.  The next day, Nobunaga celebrated the victory and gave thanks to Morinari for protecting Nagoya Castle during his absence.

Despite the capture of Muraki fortress, Nobunaga had not expelled the Imagawa from Owari.  Imagawa Yoshimoto had already succeeded in dividing Mikawa Province to the east, and had gained a foothold in the eastern portions of Owari, including Shinano Castle in the Kasugai District.  Early in 1556, Nobunaga attempted to capture Shinano by setting up a base nearby and laying siege to the castle.  However, Matsudaira Ietsugu suddenly attacked him, and he suffered the loss of over fifty men.  This left Nobunaga further from his goal of driving the Imagawa out of eastern Owari.  Nobunaga had been struggling against his opponents within the Oda clan, so he could not give full attention to the incursions by the Imagawa in eastern Owari until 1560, when the situation rapidly changed.

In 1554, the Oda invaded Suruga a second time after Imagawa Yoshimoto dispatched for Mikawa, but Takeda Shingen, an ally of Yoshimoto, provided supporting forces to halt the advance. Meanwhile, the Imagawa, the Takeda, and the Hōjō entered into the Zentoku Temple Alliance.  Yoshimoto proposed this agreement as a means to secure his northern and western flanks so he could focus on spreading his control to the east, toward the capital of Kyōto. The meeting took place at Zentoku Temple in a border region between the provinces of Sagami, Kai, and Suruga. Yoshimoto had studied at this temple with his brother in their youth.  The agreement reaffirmed the existing alliance between the Imagawa and the Takeda, and halted conflict between the Imagawa and the Hōjō that had continued sporadically for over eighteen years.

Through the mediation of Taigen Sessai, a senior retainer of Yoshimoto, the lords agreed to an interlocking series of marriages to seal the alliance.  These included the marriage between Yoshimoto’s daughter and Takeda Yoshinobu, the eldest son and heir of Shingen.  Shingen agreed to the marriage of his daughter to Hōjō Ujimasa, the son of Ujiyasu.  Finally, Ujiyasu consented to the marriage of his daughter to Imagawa Ujizane, the eldest son and heir of Yoshimoto.  This strategic alliance allowed Yoshimoto to focus on the Oda to the west, Shingen turned his attention to Uesugi Kenshin in the north, and Ujiyasu achieved his aim to dispatch troops to the Kantō Region.

Yoshimoto gained power through the exercise of superior strategic skills, leadership, and administrative prowess.  Although not known for fierce bravery and valor on the battlefield like Takeda Shingen and others, his abilities enabled him to forge alliances, command tens of thousands of men, and devise policies to generate the economic development and resources needed to further expand his domain.  Yoshimoto further benefited from the abilities of those in his inner circle, including the former monk, Sessai Taigen, an outstanding military commander of considerable stature in the clan.

Yoshimoto exploited the confusion within the Oda clan following the death of Nobuhide to further encroach on eastern portions of Owari.  Nobunaga clashed with the Imagawa at Muraki in 1554, and at Shinano in 1556, but he had been unable to fully confront the threat owing to the lengthy struggle within his own clan.  By 1560, Yoshimoto had forged strategic alliances with powerful warlords, while Nobunaga had yet to garner control of Owari.  Yoshimoto stood closer than anyone toward becoming the most dominant warlord in Japan; but success had clouded his vision, making him oblivious to the danger awaiting him as he meandered through enemy territory.

B.  The Battle of Okehazama

By 1560, Nobunaga had achieved his goal of eliminating opposition to his rule within the Oda clan.  He set about to restore local villages ravaged by war and to restore order in Owari.  He also turned his attention to the threat from the Imagawa.  The Oda and the Imagawa controlled numerous castles and forts situated in close proximity around a critical border region between Owari and Mikawa on the Chita Peninsula.  This served as an important crossroads for merchants and armies traveling by sea through the Ise and Mikawa bays and by land over the Tōkaidō.  The Tajimi District in neighboring Mino Province accounted for over sixty percent of the production of pottery in the country during this period, and enterprises affiliated with the Ise Shrine engaged in the distribution of coveted Tokoname pottery.  Traders from this region distributed all variety of bowls, containers and utensils used throughout Japan.        

Revenues generated from commerce on the Chita Peninsula considerably outweighed benefits obtained from other rice-growing regions.  Moreover, the strategic importance of the location made it a coveted territory to the Oda as well as the Imagawa.  Earlier administrators of the peninsula included the Isshiki and Ise families under the Muromachi bakufu.  Other wealthy merchant families, such as the Mizuno and the Saji, operated here at the time the peninsula came under the control of Oda Nobuhide in Owari.  In 1548, Yoshimoto sought to capture Ōdaka Castle from the Oda, ordering Nonoyama Masakane to attack, but he did not survive.

Having defected to the Imagawa years earlier from Narumi castle, and battling the Oda to a stalemate, Yamaguchi Noritsugu showed conspiratorial prowess by garnering control of Ōdaka and Kutsukake castles.  Yoshimoto assigned Udono Nagateru to Ōdaka, while Kondō Kageharu defended Kutsukake.  Ōdaka castle stood on the front lines of the border between the Oda and the Imagawa, playing a central role in Yoshimoto’s designs to wrest control of the entire Chita Peninsula away from the Oda.  The capture of Kutsukake severed travel over land or water to eastern Owari.  Imagawa forces from Kutsukake crossed the Tenpaku River to attack Hoshizaki Castle.       

To counter the Imagawa forces at Narumi, Ōdaka, and Kutsukake castles, Nobunaga fortified an old residence at Tange, dispatched Sakuma Nobumori to the fortress of Zenshōji to the north of Narumi, and Kajikawa Takahide to Nakashima to the south. Between Narumi and Ōdaka, he built additional fortresses at Marune and Washizu, assigning Sakuma Morishige to Marune and Oda Hidetoshi, his great uncle, to Washizu. This build-up posed a direct challenge to Yoshimoto’s presence in Owari in the days leading up to his march to Kyōto.

1.  Imagawa Yoshimoto’s Entourage

Hearing these developments from his men at Narumi and Ōdaka, Yoshimoto set out from his headquarters in Sunpu Castle on the twelfth day of the fifth month of 1560.  He left his son, Ujizane, in charge of the headquarters.  Ujizane had a long record of demonstrating administrative prowess in Suruga and Tōtōmi, including the introduction of liberalized rules to promote commerce among merchants.  He also defended territory against incursions by Takeda Shingen.  Finally, Ujizane held a deep and unabiding interest in the arts, having personally composed as many as one thousand seven hundred Japanese odes known as waka.  These achievements, however, did not compensate for the later demise of the Imagawa clan under his failed command.

An initial skirmish occurred prior to the famous Battle of Okehazama.  In order to check the advance of Imagawa troops from Sunpu, Nobunaga led his men into the Kichiro District of Mikawa Province, whereupon, on the fifth day of the fifth month, he had them set fires.  The resulting conflagration destroyed the Jisshō Temple, and the advance descended into a rampage among the attacking troops.

Yoshimoto led twenty-five thousand men, including advance forces, patrols, and the rear guard, making up the largest army in the Tōkai Region.  Some literature suggests the contingent totaled as many as forty thousand men, but this may have been misinformation intentionally designed to intimidate enemies.  Members of the contingent came from all three provinces under Imagawa control, including the home province of Suruga, in addition to Tōtōmi and Mikawa to the west of Suruga.  Yoshimoto departed with the intention of pronouncing himself to the Court in Kyōto as the supreme ruler of Japan.  The impressive size of his contingent, his decision to ride in a bright red, ornate palanquin – a special privilege granted by the shōgun – and his personal attire and preparations, including a powdered face, blackened teeth, and elaborate dress, created the air of a formal procession.  Preceding the excursion, Yoshimoto acquired the official rank of Protector of Mikawa, and he may have been on course to obtain even higher titles, as that of the earlier shōgun, Ashikaga Takauji.

None of the literature of the period regarding Imagawa states that the purpose of the excursion was to march upon Kyōto.  Rather, this purpose is stated in military chronicles written later in the Edo period, in the early seventeenth century.  Considering the movements of Yoshimoto during this stage of conquest, the contingent may have been formed to intimidate Nobunaga, and to expand Yoshimoto’s sphere of influence in Owari.  According to one account, Yoshimoto was not particularly adept at riding, and even fell off a horse in the early stages of the journey.

On the seventeenth, Yoshimoto and his men advanced to Kutsukake, located a mere a half-day journey from Nobunaga’s new headquarters at Kiyosu castle and even closer to Narumi and Ōdaka castles.    Yoshimoto held a strategy session that evening, during which he ordered Tokugawa Ieyasu to supply provisions to Ōdaka Castle. 

The following morning, he dispatched two thousand five hundred men to each of Narumi and Ōdaka castles, both located in Owari but under the control of the Imagawa.  The men carried provisions, and used the castles as staging areas to launch attacks on the Oda fortresses of Washizu and Marune.  Ōdaka Castle had a special meaning for Ieyasu based on its connection to the Mizuno clan from which his mother, Odai-no-kata, originated.  Odai-no-kata was the daughter of Mizuno Tadamasa and formal wife of Matsudaira Hirotada – a political marriage between the Mizuno and Matsudaira clans.  These friendly acquaintances at Ōdaka may later have helped him to return to the safety of Okazaki Castle after the sudden attack on Yoshimoto.

Late in the evening on the eighteenth, Asahina Yasuyoshi commenced the engagement by leading about two thousand men to Washizu fortress.  Around five hundred men under the command of Iio Sadamune, a relative of Nobunaga, defended the castle.  The defenders could not repulse the unexpected attack, and the fortress fell that evening.  Oda Hidetoshi, Nobunaga’s great uncle, died in the battle. 

That night, Ieyasu led an advance guard of about one thousand men.  They stormed the Marune fortress at the same time as the attack on Washizu.  Sakuma Morishige, a commander in Nobunaga’s army, defended the fortress, but, like their counterparts at Washizu, Morishige and his four hundred troops succumbed to the onslaught that evening.  Nobunaga had no more than three thousand men at his disposal, and could not spare any of them in a vain attempt to save the fortresses.  Meanwhile, Yoshimoto did not expect Nobunaga to leave the protection of Kiyosu Castle, so he mobilized other troops to attack the Nakashima and Zenshōji fortresses. 

Yoshimoto set out with his men from Kutsukake on the morning of the nineteenth.  He dressed in full battle garb, with white chest armor, a helmet inlaid with a golden dragon, a red silk overcoat, and a cherished sword at his side.  The dispatch of many of his men to attack the fortresses reduced the contingent.  They planned to follow the path of the advance troops to Ōdaka castle.  Along the route, Yoshimoto encountered Shintō priests and peasants who paid tribute to his procession.  According to one account, Yoshimoto came across Hachisuka Masakatsu, a retainer of Nobunaga sent under the disguise of a local peasant honoring Yoshimoto.  Masakatsu and his band of followers groveled in front of the procession, and spread out a white cloth piled high with offerings to show respect.  Yoshimoto received Masakatsu’s greetings without suspicion, and Masakatsu used the opportunity to suggest to a retainer an alternative route to Ōdaka, urging them to pass through a nearby basin because the shaded valley would provide relief from the hot, sultry weather.

Yoshimoto may have proceeded according to a predetermined route, or a route decided upon after consultation with local persons.  The risk of deception and their entrance into a hostile area suggests a planned route.  Moreover, whether the army would depend upon the advice of unknown locals who they happened to encounter along the way is uncertain.  Nevertheless, the spirited Yoshimoto chose the route through the valley, proceeding with his men in a long line, arranged in groups across of three and three, then five and five.  Unaware of the trap, he headed straight into the long, narrow basin of Denraku-hazama in the northern portion of Okehazama.     

Yoshimoto took a break for the noon meal atop the northern side of Mt. Okehazama, a hillock, chosen by his advance forces as early as two days before Yoshimoto’s arrival. Around this time, Yoshimoto received news that his men had succeeded in capturing Nobunaga’s two key outposts at Washizu and Marune.  Sitting near his lacquered palanquin, and encircled by a handful of men, Yoshimoto enjoyed the festive mood of victory.  He sang with a sonorous voice, confident in the belief that he would soon pronounce himself ruler of Japan.  Yoshimoto boasted to his men that even demons would flee in the presence of his banner, and overcoming the young lord of Owari would be a small step on his path of conquest.

2.  Nobunaga’s Response

Nobunaga knew that he must stop Yoshimoto from further expanding the territory in Owari under his control, and marching to Kyōto.  If Nobunaga failed, Yoshimoto would hold sway over the whole country; but, at most, Nobunaga had only about five thousand troops at his disposal, and many of these needed to defend fortresses within Owari.  He could hope to muster only about three thousand men to engage Yoshimoto.  A direct assault, even if fought valiantly, would inevitably result in a loss for Nobunaga through the attrition of forces.  He had to devise a plan to overcome a more powerful and menacing opponent.

Prior to deciding his next step, Nobunaga consulted with his chief retainers at Kiyosu Castle.  Hayashi Hidesada and others preferred to remain in Kiyosu Castle.  This had some obvious advantages.  The castle stood atop a natural dam on the Gōjō River that traversed along its east bank.  Towering walls and moats made it difficult to approach.  Further, the defenders could count on support from men based at the nearby castles of Iwakura, Nagoya, Shobata, Moriyama, and Suemori.  If the battle dragged on, Yoshimoto would be pressed for supplies to meet the needs of his contingent, giving the defenders a chance to strike back.  An attacker generally needed ten times as many men to take a castle than to defend one.  This plan offered at least a marginal hope for victory.  The retainers viewed a first strike as a risky venture compared to the security of staying in the castle, and Yanada Masatsuna stood alone as the only bushō in support of a field battle. 

The thought of squaring off against Yoshimoto entailed significant risks of its own, but other possible scenarios gave Nobunaga even more concern.  A steadfast warlord, Yoshimoto would, if given the opportunity, devise a strategy to dictate the terms of a confrontation.  Nobunaga recalled his father’s defeat to Yoshimoto at Azukizaka in the third month of 1548.  At the time, Yoshimoto could have proceeded to attack Anjō Castle, but found it more prudent to carry this out the following year after regrouping his forces.  Nobunaga considered the risk if Yoshimoto made a similar two-phase attack on Kiyosu.  In the first phase, he could advance with his men to the Shonai River, forcing Nobunaga to concede all territory to the east of the river without serious resistance.  This would give control to Yoshimoto of over half of the province.  After reorganizing his forces, in the second phase, Yoshimoto could then storm the castle.  This scenario did not bode well for Nobunaga and his men.  Nobunaga knew that a failure to kill Yoshimoto would be catastrophic, so he remained intent on this objective.

Nobunaga considered the possibility that Yoshimoto would march to Kyōto to receive official sanction for his expanding regional hegemony.  In the prior year, Nobunaga visited Ashikaga Yoshiteru, the shōgun, to receive an appointment as the provincial governor of Owari.  Now that Yoshimoto had the power to seize Owari, prior recognition from the shōgun would give his conquest credibility.  The Muromachi bakufu had fallen into a state of irretrievable decline, but warlords continued to seek their support to legitimize their acts.

Nobunaga could have bravely faced defeat by heading to the border to confront Yoshimoto and his men.  At least this way the men could die with honor.  Upon hearing this, according to one anecdote, Nobunaga danced around laughing, refusing to consider this or the other alternatives proposed.  His retainers feared that the end of the Oda clan was near at hand.  Despite the merits of these proposals, Nobunaga knew that dictating the terms of engagement offered the only glimmer of hope he had to stop Yoshimoto.  In the end, he rejected the proposals of his commanders and decided to launch a surprise attack on Yoshimoto.

He sent his commanders home that night, and may have informed them of his plan. However, owing to his tendency to follow his own intuitions rather than seek the opinions of his subordinates, he may have dismissed them without voicing his decision. Nobunaga intimidated even those in his inner circle.  His explosive temper kept subordinates off-guard.  They feared looking into his eyes, and withdrew from his presence in response to the slightest signal.  He led and retained his army through the artful exercise of power.

Owing to the ever-present risk of secret collaborators, these times dictated that the means to deceive an opponent began with the deception of one’s allies.  Nobunaga understood that the consequences of having his secret plan uncovered meant certain defeat.  This gave him reason to conceal his true intentions until the last possible moment.  With no orders to prepare the castle for an imminent attack, the retainers had no choice other than to accept the prospect of a field battle as their unwelcome fate.

Confident of strength in numbers, Yoshimoto did not make a preliminary investigation of the geography along the route cutting through Owari, reflecting his underestimation of Nobunaga.  Quite to the contrary, Nobunaga scrupulously forged a plan that took into account all matters from the route traveled to the frame of mind of his enemy.  The army of five thousand men in Yoshimoto’s immediate contingent would be unstoppable in a head-on clash.  To pass through the valley, Nobunaga knew that the army would need to travel in a long narrow procession.  This meant that a lateral strike offered the opportunity to catch Yoshimoto individually without having to confront the entire army. Betting all he had on this insight, Nobunaga believed that he could stop Yoshimoto despite the odds against him. 

To carry out his plan, Nobunaga drew heavily upon one of his foremost skills – the use of information as a tactical weapon.  He studied the terrain surrounding the route traveled by Yoshimoto and identified the most favorable location for an attack.  He further dispatched spies to provide him with continuous information on the movements and status of Yoshimoto’s contingent.

Nobunaga spread misinformation to divide and weaken his opponents prior to an engagement.  Nobunaga’s response to a betrayal by Tobe Masanao, a commander stationed at Tobe Castle in the Kasadera District of Owari illustrated this tactic. Observing Yoshimoto’s gradual expansion into Owari, Masanao believed, following the death of Nobuhide, that the balance of power had shifted Yoshimoto.  In response to solicitations from Yoshimoto, including an offer to marry Yoshimoto’s younger sister, he decided to abandon the Oda clan.  According to the order of the day, loyalty ran only as deep as the power of a warlord to defend his retainers.  Nobunaga responded by gathering all documents written by his former commander, and ordered a scrivener to practice copying these documents until he could imitate Masanao’s writing style.  It took almost a year, but once the scrivener mastered the style, in 1557, he drafted a secret letter appearing to be from Masanao to Nobunaga stating an intention to betray Yoshimoto.  Nobunaga then had one of his retainers dress up as a merchant and pass the letter, as though intercepted, to the Imagawa.  As a result, Yoshimoto executed Masanao.

Nobunaga made further use of misinformation to eliminate Yamaguchi Noritsugu. Having first clashed with Noritsugu in 1552 at the Battle of Akatsuka, Nobunaga had failed over a period of years to dislodge the betrayer.  Unable to defeat him on the battlefield, Nobunaga chose a more subversive means to eliminate his enemy.  Seven years later, in 1559, he sent a disguised retainer to Sunpu to spread a rumor that Noritsugu and his son, Noriyoshi, only pretended to be in concert with the Imagawa, and that once Yoshimoto’s contingent entered Owari, they would combine with the Oda in a pincer attack to destroy them.  Upon hearing this news, Yoshimoto summoned his unsuspecting collaborators to Sunpu, and, without confirming the veracity of the charges, forced them to take their own lives.  It was Yoshimoto’s policy to minimize all potential threats prior to an upcoming excursion, even though Noritsugu and Noriyoshi had been valuable collaborators for over seven years.  These incidents provided an advantage to Nobunaga in his ensuing encounter with Yoshimoto.

Nobunaga may have held a formal strategy session with his retainers or merely consulted with them informally and later sent them home the same evening. Nevertheless, the gravity of the situation confronting Nobunaga supports the account that a strategy meeting was indeed held.  But even if a formal meeting was not held, it is believed that the retainers were in favor of fighting from the castle rather than striking out at Yoshimoto.

Nobunaga received the news that his fortresses in Marune and Washizu had fallen before dawn on the day of his planned attack.  By some accounts, he fancifully danced and sang a famous verse along the lines of “Men live only fifty years.  Compared to the universe, it is like a mere illusion, and all who are given life also must perish.”  He had his breakfast of boiled vegetables, and headed out on horseback from Kiyosu Castle along with several peasant fighters in his wake.  Soon after his arrival at the Atsuta Shrine, as many as two hundred soldiers eagerly gathered. 

Praying for victory at the shrine, he may have had faith that some divine intervention would help.  More likely, he used the visit to further unite and encourage his men of their eventual triumph under the watchful eyes of the Shintō gods.  Nobunaga scorned religious practices and the worship of icons.  Since his youth, he rejected the behavioral norms followed by those around him, and this sense of freedom from tradition carried over to his view of religion.  A stark realist, he continually sought tactical advantage rather than spiritual consolation.  One anecdote, however, tells of a loud sound reverberating from deep inside the shrine, and then a beautiful white swan flew out. Nobunaga encouraged his men by calling this a messenger from the Atsuta god to protect them.

Another story tells of Nobunaga riding sideways on his horse as they departed, appearing quite out of his mind.  He may simply have been over-exuberant about the events at hand.  As word spread that Nobunaga was preparing for an attack, the army quickly grew to about one thousand men before leaving the shrine at eight o’clock in the morning.  Nobunaga led his contingent south to Zenshōji fortress.  After a two-hour trip, the force had swelled to as many as three thousand spirited men.  From this location, they could see smoke on the distant horizon marking the aftermath of the attacks on the Marune and Washizu outposts.  As a diversionary tactic, he sent three hundred men from Zenshōji to attack Narumi Castle, located less than a kilometer to the west, but the defenders put up stiff resistance and most of the men fell in battle.   

Around noon, Nobunaga departed Zenshōji with about two thousand men.  He left one thousand men behind to give the impression to Imagawa scouts that his main force remained behind, exercising the artful use of deception to confuse the enemy.  He assigned small groups of the cavalry to guard nearby posts.  Mizuno Nobumoto and others guarded the Tange fortress.  Nobumoto, the son of Tadamasa, had earlier broken the course followed by his father by betraying the Imagawa and siding with Nobunaga.

Nobunaga and his contingent followed a southeast course from Zenshōji, roughly parallel to the ancient Tōkaidō, and headed toward the Nakashima fortress.  They traveled on horseback along narrow footpaths between rice fields.  A sudden change in the weather brought a storm front from the north, causing a downpour with large raindrops.  This storm hindered the efforts of Yoshimoto’s men from patrolling the area, and, at the same time, allowed Nobunaga and his men to reach Nakashima fortress undetected – the key to their plan.  Nakashima lay only about two kilometers from Yoshimoto’s main contingent near the foot of Mount Okehazama.

Just after a downpour, around one o’clock in the afternoon, Nobunaga and his cavalry rushed out of the fortress to attack the ill-prepared forces taking refuge from the rain in the woods along the trail.  In most cases, attacks occurred at the break of dawn instead of the afternoon.  Nobunaga broke precedent to take advantage of the opportunity at hand to launch a suprise assault against the Imagawa troops.  The initial group of attackers startled the unexpecting Imagawa in a scene that quickly turned into unbridled mayhem.  A larger contingent of Oda men arrived an hour later by traveling on the valley road along the base of Mount Okehazama.  They chased those remaining in the direction of a larger unit on Mount Okehazama.  The Imagawa men made a futile attempt to ward off the attack with an assortment of spears, swords, and arquebuses.

Yoshimoto had unknowingly left himself vulnerable to attack, easily identifiable as he rested near his ornate palanquin.  The sudden turn of events left him no time to summon additional troops for support.  Believing the noise to be a disturbance among his own men, or possibly a rebellion, Yoshimoto barely had a chance to realize the horror of his misjudgment before he fled.  Surrounded by three hundred members of the cavalry in a tight pack, he abandoned the palanquin and raced east toward Ōdaka Castle.  Other troops may have attempted to flee to Kutsukake Castle.

After a pursuit in the foothills, only fifty of the defenders remained.  An Oda fighter named Hattori Kazutada stabbed Yoshimoto with a spear, and then Mōri Yoshikatsu beheaded him.  All together, over three thousand men were killed, and Nobunaga led a valiant march back to Kiyosu Castle with the men at the front holding out Yoshimoto’s head on display.  Without their leader to hold them together, the remaining forces fled east to their home provinces.

3.  Consequences of the Battle of Okehazama

Yoshimoto’s perilous defeat at the hands of Nobunaga left the fate of his regional hegemony to his eldest son, Ujizane.  Yoshimoto had long feared that his son lacked the ability to become a capable leader.  Even after growing up, Ujizane showed much more interest in cockfighting and kickball than the military arts or serious study, and when Yoshimoto died at Okehazama seven years after forging the alliance with his powerful adversaries, his prophecy became true.  Ujizane demonstrated neither the skill nor the conviction to support the alliance built by his father, meaning that the Imagawa clan faced eradication.  In addition to Yoshimoto, the loss of top commanders in the attack made the circumstances even more precarious for the Imagawa clan.  

Several years after the events at Okehazama, Ujizane happened to be in Kyōto just when Nobunaga marched upon the capital to pronounce his rule.  Ujizane visited Nobunaga’s quarters by himself, declaring that he wished to seek revenge for the loss of his father.  He came alone, and his countenance did not give rise to alarm.  After further inquiry, Ujizane made clear that he wanted to challenge Nobunaga to a game of kemari, and, by winning, he would have his revenge.  Nobunaga would not participate, and, instead, appointed a servant to challenge Ujizane in his game.

Soon thereafter, Takeda Shingen unilaterally rejected the alliance and invaded Ujizane from the north, and Ieyasu attacked from the west.  Ujizane surrendered to Ieyasu, and served under his dominion until the ripe age of seventy-seven.

Nobunaga achieved the stunning military upset based on a brilliant strategy to defeat a much larger foe.  The odds of victory, however, may not have been as much in Yoshimoto’s favor as appears from the size of his contingent.  The battle took place in Nobunaga’s home territory, so he had the advantage of being on familiar terrain.  A network of spies and scouts provided him with the vital information needed to create and execute a plan.  Despite having recently gained a foothold in eastern portions of the province, Yoshimoto intruded into hostile and unfamiliar territory.

At the time of the ambush, about five thousand forces accompanied Yoshimoto.  Compared to the two thousand troops in Nobunaga’s strike force, the all-important element of surprise rendered the difference insignificant.  Moreover, the hilly terrain prevented Yoshimoto from calling in additional forces, even if he had tried.

The defeat of Yoshimoto fulfilled a mission begun by Nobunaga’s father, Nobuhide.  In a single strike, it eliminated the most menacing warlord in the region, who in the prior decade had greatly expanded his fiefdom while Nobunaga focused on gaining control of his own clan.  He projected an image of power and magnetism that enabled him to draw the men and resources to expand his conquest into neighboring provinces.

The most highly decorated participant in the battle was Yanada Masatsuna, a local samurai who lived near the border between Owari and Mikawa in the village of Kutsukake.  At first sight, it seems reasonable that the samurai who struck down Yoshimoto would receive the highest honors.  Nobunaga decorated Masatsuna not because of valorous conduct during the attack, but rather the invaluable information that he furnished to make it successful.  He performed two primary roles.  First, he surveyed and reported on the movements of Yoshimoto’s entourage, including the route from Kutsukake to Ōdaka, the number of troops, and the location for the noon break. This information helped Nobunaga to devise his attack plan.  Second, he led Nobunaga and his men to the optimal location for the ambush.  Intimately familiar with the local terrain, Masatsuna fulfilled this role without detection from Yoshimoto’s forces and his scouts, not to mention he was the only bushō to recommend a field attack.

Masatsuna’s contributions highlighted Nobunaga’s practice of placing people in the most suitable positions.  He realized early on that assigning subordinates to roles that exploited their knowledge of specific locales could yield stunning results.  Ironically, the success of his surprise attack drew so much attention that Nobunaga never used this tactic again.  Perhaps he never again confronted circumstances requiring such a response, but after word spread of Yoshimoto’s misfortune, enemies everywhere knew to be on alert to avoid a similar trap.

The defeat of Yoshimoto at Okehazama resulted in a sudden loss of influence by the Imagawa in Mikawa, and the resurrection of the Matsudaira clan under the leadership of Tokugawa Ieyasu.  The subsequent alliance between the Matsudaira and the Oda finally led to a cessation of hostilities along the border between Owari and Mikawa.