Battle of Nagaragawa: The Viper of Mino Slain by His Eldest Son ― How a Father-Son Feud Set the Stage for Nobunaga’s Rise

April 20, 1556 (Koji 2) | Nagaragawa River, Mino Province (modern-day Gifu City, Gifu Prefecture)

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The Battle in Three Lines

• The Battle of Nagaragawa was a clash between Saito Dosan, known as “the Viper of Mino,” and his eldest son Saito Yoshitatsu, fought for control of Mino Province — one of the most dramatic father-son conflicts of the Sengoku period
• Despite an overwhelming numerical disadvantage (2,500 vs. 17,500), and with reinforcements from his son-in-law Oda Nobunaga arriving too late, Dosan was killed in battle
• Through Dosan’s will, Mino Province was bequeathed to Nobunaga, laying the groundwork for Nobunaga’s later conquest of Mino and his “Tenka Fubu” (rule the realm by force) campaign for national unification

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The Mainstream Account — The Textbook Version

Why the Battle Happened

Following the Onin War (1467–1477), Mino Province fell into prolonged chaos as the ruling Toki clan (the provincial governors, or shugo) tore itself apart through internal conflict. Saito Dosan (originally Saito Toshimasa) rose from humble origins — his family had migrated from Kyoto to Mino as commoners — and through a series of calculated maneuvers, he successively usurped the names and positions of the Nagai and Saito clans. In 1542, he expelled the Mino governor Toki Yorinori to Owari Province, seizing the position of provincial lord for himself. He became one of the most notorious embodiments of gekokujo (the lower overthrowing the higher), the defining social phenomenon of the Sengoku era, and was later given the famous epithet “the Viper of Mino.”

Dosan had several sons. His eldest, Saito Yoshitatsu, was born to a concubine named Miyoshino (also recorded as Mihoyono). His second son Magoshiro and third son Kiheiji are believed to have been born to his official wife. In 1554, Dosan handed over the headship of the clan to Yoshitatsu and retired to Sagiyama Castle. On the surface this appeared to be a smooth succession, but tensions between father and son quickly deepened.

According to the chronicles Shincho Koki and Konoki, Dosan came to regard Yoshitatsu as a “feeble-minded old fool” and began plotting to replace him as heir with his second son Magoshiro, whom he considered far more capable. He went further by granting his third son Kiheiji the prestigious court title “Isshiki Uhyoe-no-Taifu,” elevating him to a rank that surpassed Yoshitatsu’s. Emboldened by their father’s favor, the two younger brothers grew arrogant and began openly disrespecting their elder brother. Fearing he would be disinherited entirely, Yoshitatsu resolved to confront his father.

In November 1555, Yoshitatsu feigned illness and summoned his brothers Magoshiro and Kiheiji to his residence, where he had his retainer Hineno Hironari murder them. The assassination was reportedly carried out in collusion with Yoshitatsu’s uncle, Nagai Michitoshi. Shocked by the deaths of his two favored sons, Dosan fled from Inabayama Castle (later renamed Gifu Castle) and took refuge at Ogura Castle in the Yamagata district to the northwest. The father-son rift was now beyond repair, and the two sides waited for the spring thaw to settle matters by force.

Yoshitatsu attracted strong support from the former retainers of the Toki clan. Resentment toward Dosan — who had usurped the Toki position through deceit — ran deep, and many former Toki loyalists rallied behind Yoshitatsu, treating him as a banner for the restoration of the old order. There was also a widespread rumor (discussed in detail in the theories section below) that Yoshitatsu was actually the illegitimate son of the ousted Toki Yorinori, which helped consolidate former Toki retainers around him. Dosan, by contrast, found only a handful of loyalists: the Akechi clan (Akechi Mitsuyasu, Mitsuhisa, and others), Takenaka Shigemoto (father of the famous strategist Takenaka Hanbei), Dosan’s other sons Saito Toshitaka and Saito Toshiharu (younger brothers of Nohime), and the warrior Shibata Kakunai.

Dosan had previously married his daughter Kicho (also known as Nohime) to Oda Nobunaga of Owari Province, forming an alliance with the rising young warlord. Their famous meeting at Shotokuji Temple in 1553 — where Dosan reportedly recognized Nobunaga’s exceptional caliber — sealed the bond between the two men. Realizing that the decisive battle with Yoshitatsu was unavoidable, Dosan called on his son-in-law for reinforcements and prepared a remarkable will: should he fall, Mino Province would pass to Nobunaga. These are the “Three Wills of Dosan” discussed later in this article.

The Course of the Battle

On April 18, 1556, Dosan advanced his army to Mount Tsuruyama, just north of Inabayama Castle. The retainers who rallied to him on Mount Tsuruyama — Saito Toshitaka, Saito Toshiharu, Akechi Mitsuyasu, Akechi Mitsuhisa, and others — numbered only about 2,700 men. Meanwhile, Yoshitatsu had assembled a massive army of approximately 17,500 troops below Inabayama Castle. The disparity was roughly six to one. The verdict on the battlefield seemed foregone before a single arrow was loosed. Since Dosan had already transferred clan headship to Yoshitatsu and had himself acquired Mino through deception, almost no local lords were willing to support him.

Detecting Dosan’s movements, his son-in-law Oda Nobunaga dispatched a relief force, crossing the Kiso and Hida Rivers by boat to advance to Daira (modern-day Hashima City, Gifu) at Toshima and Tozobo. He was still about 10 kilometers from Dosan’s position on Mount Tsuruyama. Though Nobunaga pushed his army with all possible speed, the battle would be decided before he could arrive.

At dawn on April 20, Yoshitatsu’s army crossed the Nagaragawa River and attacked Dosan’s forces. The vanguard was led by Yoshitatsu’s senior retainer Takenokoshi Dochin. Dosan, renowned as a master tactician, repulsed the vanguard skillfully and even killed Takenokoshi Dochin in the engagement. In the opening phase of the battle, Dosan’s forces fought brilliantly despite their overwhelming numerical inferiority.

Seeing his vanguard defeated, Yoshitatsu personally led his elite guard (hatamoto) across the river. At this point, a Yoshitatsu warrior named Nagaya Jinemon issued a formal challenge for single combat — a ritualized duel between champions. Shibata Kakunai of Dosan’s army accepted, and in the ensuing duel, Kakunai killed Nagaya. Once again, Dosan’s outnumbered force had drawn first blood. But Yoshitatsu, realizing that further setbacks could not be tolerated, ordered a full assault. Against such crushing numbers, Dosan’s army finally broke.

According to Shincho Koki, Dosan was killed in the chaos of the rout. The first warrior to thrust a spear into him was Nagai Michikatsu, who sliced off Dosan’s nose. Then Komaki Genta, swept up in the momentum, cut off Dosan’s leg at the shin and took his head. The original plan had been to take Dosan alive, but in the frenzy of the moment things went otherwise; Nagai Michikatsu reportedly took Dosan’s severed nose as evidence of his feat. Dosan was 63 years old at his death. The contemporary chronicle Daikosama Gunki no Uchi records that as Dosan watched his son’s masterful command in his final moments, he exclaimed “Truly, the son of Dosan!” — recognizing at last the abilities of the son he had spent a lifetime dismissing as a fool. It was a poignant final acknowledgment from a father who had been mistaken to the very end about his eldest child.

Upon hearing of Dosan’s death, Nobunaga decided to retreat. Compounding matters, Oda Nobuyasu of the upper four districts of Owari — who had sided with Yoshitatsu — rose in revolt at Iwakura, forcing Nobunaga to abandon any deeper push into Mino (Shincho Koki, Konoki). The Akechi clan’s home castle of Akechi Castle, having sided with Dosan, was attacked by Yoshitatsu’s forces after the battle and fell. Akechi Mitsuhide (who was reportedly Dosan’s retainer at the time) became a ronin and fled Mino, eventually finding refuge with the Asakura clan of Echizen Province.

The Aftermath

With his victory at Nagaragawa, Yoshitatsu became the undisputed lord of Mino. Bearing the burden of patricide, he turned to consolidating internal affairs. He reorganized his retainer corps by incorporating former Toki loyalists, brought temples and shrines under his control, conducted land surveys, and steadily strengthened his position as a daimyo. In 1558, he received the court title “Jibu-no-Taifu” from the imperial court — a position traditionally granted to those of Seiwa Genji lineage — and used it to assert his legitimacy as a “descendant of the Toki clan.” Around the same time, the 13th Ashikaga shogun, Ashikaga Yoshiteru, granted him permission to adopt the prestigious surname of the Isshiki clan, allowing him to claim membership in the Ashikaga family lineage.

Yoshitatsu’s relationship with the Oda clan deteriorated after Dosan’s death. He clashed with Nobunaga over the Mino-Owari border in skirmishes such as the Battles of Shinano and Okusa in 1558, and continual minor engagements followed. Anxious to fortify his defenses before Nobunaga could mount a full invasion, Yoshitatsu accelerated the reorganization of his retainer corps and the strengthening of castle defenses. His administrative abilities were far from mediocre; some historians argue he was an even more effective ruler than his father. Though Yoshitatsu has long been pigeonholed as the “villainous son who killed his father,” he was in reality a capable Sengoku daimyo.

Yoshitatsu’s reign, however, was short-lived. In May 1561, he died suddenly at the age of 34. The cause is officially recorded as illness, though some sources suggest he wasted away from leprosy. His heir, Saito Tatsuoki, was only 14 years old at the time and lacked his father’s capabilities. Unable to control his retainers, he watched as the powerful “Three Heroes of Western Mino” — Inaba Ittetsu, Ujiie Naomoto, and Ando Morinari — defected to Nobunaga, and the Saito power structure began to disintegrate.

In 1567, Nobunaga defeated Tatsuoki at the Battle of Inabayama Castle and finally conquered Mino. Tatsuoki fled to Ise Nagashima and later sought refuge with Asakura Yoshikage in Echizen. In August 1573, Tatsuoki was killed at the Battle of Tonezaka during Nobunaga’s campaign against the Asakura, and the Saito clan of Mino — built by Dosan — was extinguished after only three generations.

The Battle of Nagaragawa was far more than a father-son confrontation. It was a decisive prelude to Nobunaga’s national unification. Dosan’s will, bequeathing Mino to his son-in-law, was fulfilled 11 years later when Nobunaga captured Inabayama Castle. The old Sengoku adage “He who controls Mino controls the realm” might well be said to begin with this very battle.

→ For more details, see the warlord articles “Saito Dosan” and “Saito Yoshitatsu“

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Alternative Theories — Exploring Different Perspectives

【Theory 1】The Two-Generation Conquest of Mino — How the “Rokkaku Shotei Jojo Utsushi” Overturned the Old Account

The image of Saito Dosan as “an oil merchant who seized a province” — the “Viper of Mino” — is deeply rooted in popular imagination. Novels such as Shiba Ryotaro’s Kunitori Monogatari and Sakaguchi Ango’s Nobunaga have repeatedly portrayed Dosan as the archetypal symbol of gekokujo. Recent scholarship, however, has substantially rewritten this account.

The Traditional View — “Dosan’s One-Generation Conquest”

Since the war chronicles of the Edo period, Dosan’s life has been told as follows: born as a monk at Myokakuji Temple in Kyoto, he renounced his vows, traveled to Mino as an oil merchant, rose to become a retainer of the Toki clan, and eventually clawed his way to the position of provincial lord. The drama of a single generation rising from commoner to daimyo has been cherished as a quintessential Sengoku narrative.

The New View — “The Two-Generation Conquest” (Yokoyama Sumio, 1983)

This conventional account was overturned by the discovery of a Showa-era document called the “Rokkaku Shotei Jojo Utsushi” (1560). This is a letter written by Rokkaku Shotei (Yoshikata), the governor of Omi Province, to his retainer, explaining the wickedness of the Saito clan in order to call off the engagement between his son and Yoshitatsu’s daughter. Within it, Yoshitatsu’s grandfather (in other words, Dosan’s father) is described as a man who “renounced his vows at Myokakuji Temple and rose to prominence in Mino,” while Yoshitatsu’s father (Dosan) is described as one who “murdered successive heads of the Nagai clan, usurped their offices, and rose to become a member of the Saito clan.”

In his paper “The Two Renunciations of Saito Dosan” (Gifu Shigaku No. 77, 1983), Yokoyama Sumio offered an interpretation of this source. The first half of Dosan’s life as traditionally told — monk at Myokakuji, renunciation of vows, oil merchant, Nagai retainer — was in fact the life of Dosan’s father, Nagai Shinzaemonjo. Dosan’s “seizure of the province” was the result of a long-term strategy spanning two generations.

The Achievements of the Father, Nagai Shinzaemonjo

Nagai Shinzaemonjo (also known as Shogoro) migrated from Kyoto to Mino and entered the service of Nagai Nagahiro. He distinguished himself in the Funada Rebellion of 1495 and gradually rose to become a powerful Nagai retainer, eventually adopting the name “Nagai Bungo-no-Kami.” He intervened in the Toki clan’s succession dispute and succeeded in placing Toki Yorinori on the de facto seat of provincial lord. Shinzaemonjo died around 1533, and his position was inherited by his son Dosan.

Dosan’s own activities begin with this inheritance of the Nagai position after his father’s death. In 1530 he killed his lord Nagai Nagahiro and took the name Nagai Shinkuro Toshimasa; in 1538, with the death from illness of the deputy governor Saito Toshiyoshi, he inherited the Saito surname. In 1542 he completed his ascent by expelling Toki Yorinori to Owari and seizing the lordship of Mino. These were genuinely rapid rises within a single generation — but every one of them was made possible by the foundation his father had laid.

The “Viper” Nickname Is Also Recent

Another intriguing finding: the term “Viper of Mino” cannot be confirmed in any source prior to Sakaguchi Ango’s Nobunaga (1947). The image was popularized by Shiba Ryotaro’s Kunitori Monogatari, but there is no historical evidence that Dosan was actually called “the Viper” during his lifetime. “Viper of Mino” is a modern literary nickname rather than a Sengoku-era epithet.

The true Dosan was not a single-generation strongman who clawed his way up from oil merchant to lord, but rather a man who inherited his father’s foothold — a foothold that had itself been built up by a Kyoto migrant — and parlayed it into provincial lordship. He represents the classic “retainer-style upstart” of the Sengoku period. The “two-generation conquest” theory offers a more accurate picture of how power succession actually worked in the Sengoku era.

【Theory 2】Was Yoshitatsu Really the Illegitimate Son of Toki Yorinori?

The most famous popular explanation for Yoshitatsu’s motive at Nagaragawa is the claim that “Saito Yoshitatsu was the illegitimate son of Toki Yorinori.” Repeatedly told in Edo-period war chronicles, the theory is now generally rejected by historians.

The Popular Account

Early modern texts like Mino-no-Kuni Sho-Kyuki, Noyo Sho-shi Denki, Mino Meisaiki, and Toki Ruidaiki tell roughly this story: Toki Yorinori’s favored mistress, Miyoshino (Mihoyono), was already pregnant with Yorinori’s child when she was given to Dosan; the child born of this pregnancy was Yoshitatsu; upon learning that he was in fact Yorinori’s son, Yoshitatsu resolved to kill the man who was both his stepfather and his father’s enemy. The Battle of Nagaragawa was thus framed as “the dramatic revenge of a son of Toki Yorinori against the man who had stolen his father’s domain.”

Rejection by Contemporary Sources

The trouble is, none of the contemporary primary sources support this story. Early texts such as Ota Gyuichi’s Shincho Koki and Daikosama Gunki no Uchi, Oze Hoan’s Hoan Shincho Ki, Yamaga Soko’s Buke Jiki, and Konoki contain no mention of a woman named Miyoshino or Mihoyono at all. The “Rokkaku Shotei Jojo Utsushi” (1560) makes no mention of Yoshitatsu having a different biological father. On the contrary, Daikosama Gunki no Uchi records Dosan saying at the end “Truly, the son of Dosan!” — Ota Gyuichi clearly treats Yoshitatsu as Dosan’s biological son.

Early modern genealogies are also divided. While Kansei Choshu Shokafu lists Yoshitatsu as Yorinori’s son, the older Kanei Shoka Keizuden contains no such claim. The pattern is consistent: older sources tend to record Yoshitatsu as Dosan’s biological son, while later Edo-period texts increasingly identify him as Yorinori’s illegitimate child.

Why the Theory Was Invented

So why did the “Yorinori illegitimate son” theory emerge? According to scholars like Kinoshita Satoshi, it was “an after-the-fact fabrication invented to justify Yoshitatsu’s patricide.” In the Confucian moral framework of the Edo period, patricide was the gravest of all crimes. If Yoshitatsu had simply killed his real father for political power, he would stand condemned as the worst kind of unfilial son. To rehabilitate his memory, the story was constructed: Dosan was not Yoshitatsu’s real father — Yorinori was — and Yoshitatsu killed Dosan to avenge his true father.

Edo-Period Context

Another contextual factor is that during the late Edo period, retired daimyo frequently returned to political life. In Edo society, the political return of a retired daimyo was unremarkable, which made the Yoshitatsu-Dosan conflict — a retired father killed by his heir — seem inexplicable as a “normal” succession dispute. The dramatic motive of “Yoshitatsu was actually Yorinori’s son” may have been retrofitted to fill this perceived gap.

The Current Scholarly Consensus

Contemporary historians dismiss the Yorinori illegitimacy theory as a folk tale. Yoshitatsu was Dosan’s eldest son by a concubine, and he himself understood this. The father-son conflict was, by current consensus, a straightforward power struggle and succession dispute. Yoshitatsu was not “a hypocritical filial son who masked his patricide with the cloak of revenge,” but rather “a Sengoku realist who killed his father to preserve his own headship and life.”

【Theory 3】The Murder of Yoshitatsu’s Brothers — The Truth Behind November 1555

The direct trigger for the Battle of Nagaragawa was Yoshitatsu’s murder of his brothers in November 1555. Knowing that his father had been increasingly favoring his younger brothers, Yoshitatsu struck preemptively to prevent his own disinheritance.

How the Incident Unfolded

According to Shincho Koki, Yoshitatsu feigned illness and took to his bed. He then summoned his brothers Magoshiro and Kiheiji, saying he wished to see them before he died. The two younger brothers came to Yoshitatsu’s residence having laid down their arms — only to be cut down by Yoshitatsu’s retainer Hineno Hironari (who would later become a powerful figure in the Saito clan), who had been waiting in ambush.

The incident is said to have been planned with the cooperation of Yoshitatsu’s uncle, Nagai Michitoshi. Michitoshi was Dosan’s younger brother (or possibly older brother by a concubine), making him Yoshitatsu’s uncle. Shincho Koki records that he and Yoshitatsu conspired to assassinate the brothers. Nagai Michitoshi would go on to serve as a senior commander on Yoshitatsu’s side at the Battle of Nagaragawa.

What the Incident Meant

The murdered brothers, Magoshiro and Kiheiji, were most likely the sons of Dosan’s official wife, while Yoshitatsu was the son of a concubine — a fragile position as heir. From the moment Dosan began moving to install Magoshiro as the new heir and to grant Kiheiji the prestigious Isshiki surname, Yoshitatsu’s disinheritance seemed only a matter of time. To kill his brothers first was, for Yoshitatsu, a desperate act of self-preservation aimed at protecting both his life and his position.

Receiving news of the killings, Dosan fled Inabayama Castle (later Gifu Castle) and took refuge at Ogura Castle (the old Toki stronghold) in Yamagata district, about 30 km to the northwest. From that point, the conflict between father and son could only be resolved by force. When the winter snows melted the following spring, the decisive Battle of Nagaragawa would follow.

Yoshitatsu’s State of Mind and the Name Change to “Hanka”

Noteworthy is that Yoshitatsu changed his name to “Hanka” during this period. Taikoki claims he adopted the name after seeing Dosan’s severed head, repenting his crime and adopting “Hanka” to expiate the sin. However, the “Mieji Monjo” documents show Yoshitatsu was already using the name “Hanka” in an edict issued from Mieji Temple in December 1555 — six months before he killed his father. The name change, then, was not “remorse after patricide” but rather “a declaration of intent before patricide.”

“Hanka” refers to a figure in Chinese lore said to have “cut off his father’s head and been hailed for filial piety” (though the historicity of this story is unverified). The historian Kuwata Tadachika has interpreted Yoshitatsu’s adoption of the name as expressing the logic that “to cut off the head of his stepfather Dosan was to avenge his real father Toki Yorinori — thus an act of filial piety toward his real father.” But Kuwata’s interpretation presupposes the Yorinori illegitimacy theory, and is therefore viewed skeptically today. A more psychologically plausible reading is that Yoshitatsu was steeling himself for the patricide by aligning his fate with a Chinese precedent — a defiant act of self-justification rather than literal filial piety.

【Theory 4】Akechi Mitsuhide’s Participation and Dosan’s Retainers

One striking feature of the Battle of Nagaragawa is that Akechi Mitsuhide — one of the central figures of late Sengoku history — is said to have fought on Dosan’s side. The battle is therefore seen as a defining moment in Mitsuhide’s life trajectory.

The Akechi Clan on Dosan’s Side

Among the 2,700 men who gathered with Dosan on Mount Tsuruyama were members of the Akechi clan — Akechi Mitsuyasu, Akechi Mitsuhisa, and others. At the time, Mitsuhide was a young member of the Akechi clan based at Akechi Castle (in modern Kani City, Gifu), and reportedly fought alongside his uncle Mitsuyasu. The Akechi were a branch of the Toki clan and might naturally have sided with Yoshitatsu (who was being treated as the banner of Toki restoration). But the Akechi were also bound by marriage ties to Dosan through his daughter Nohime, and thus chose Dosan’s side.

After the battle, Akechi Castle was attacked by Yoshitatsu’s forces and fell. Akechi Mitsuyasu committed seppuku, and the young Mitsuhide escaped Mino as a ronin. He eventually took refuge with Asakura Yoshikage of Echizen and entered upon a long period of wandering. The path that would eventually take Mitsuhide into the service of Ashikaga Yoshiaki, then into Oda Nobunaga’s army, and ultimately to the assassination at Honnoji — all began at the Battle of Nagaragawa.

Takenaka Shigemoto, Father of Takenaka Hanbei

Another noteworthy participant on Dosan’s side was Takenaka Shigemoto, father of the legendary strategist Takenaka Hanbei, who would later serve Toyotomi Hideyoshi. Hanbei himself was only 12 years old at the time, but the strategic acumen and judgment he would later display drew on his family’s deep experience as Sengoku-era retainers.

Other Dosan-Side Retainers

Other warriors who fought valiantly for Dosan included Saito Toshitaka and Saito Toshiharu (Dosan’s sons by another mother — half-brothers of Yoshitatsu), and Shibata Kakunai (who killed Nagaya Jinemon in the single-combat duel). Toshitaka and Toshiharu took refuge with the Oda after the battle and went on to serve Nobunaga. Toshiharu, who was a younger brother of Nohime, effectively continued the Saito of Mino lineage within the Oda household. He died at Nijo Castle during the Honnoji Incident, fighting alongside Oda Nobutada (Nobunaga’s heir).

Though the Battle of Nagaragawa was decided in a single day, it dramatically reshuffled the human networks of the Sengoku era. Akechi Mitsuhide, the Takenaka father-son pair, Saito Toshiharu — many of those who fought for Dosan would go on to become central figures in the Nobunaga and Hideyoshi regimes. As a hinge point of historical causation, the Battle of Nagaragawa occupies a unique place in Sengoku history.

【Theory 5】The Three Wills of Dosan and the Bequest of Mino to Nobunaga

On the eve of the Battle of Nagaragawa, Dosan sent a will to his son-in-law Oda Nobunaga bequeathing Mino Province to him. These documents — known variously as “Dosan’s wills” or “the deeds of cession to Nobunaga” — are among the most important documents of Sengoku history.

Overview of the Wills

Three of Dosan’s wills survive, all dated April 19, 1556 — the day before the decisive battle. Their content states that if Dosan should die in his battle against Yoshitatsu, the province of Mino was to be bequeathed to his son-in-law Oda Nobunaga. One of the three is thought to have been handed to Saito Toshiharu (Dosan’s son and Yoshitatsu’s half-brother), who fought on Dosan’s side at Nagaragawa, and later carried it to the Oda army after the battle, delivering it to Nobunaga.

The reason Dosan prepared such a will on the eve of battle was that he foresaw his defeat. With a sevenfold disadvantage in numbers, even a master tactician like Dosan could see victory was unlikely. The province he ruled was one he had usurped through deception, and almost no local lords were willing to support him. As a last resort, Dosan entrusted Mino to his son-in-law.

The Connection to Nobunaga’s Conquest of Mino

Dosan’s will became the justifying basis for the Oda clan’s subsequent conquest of Mino. After Dosan’s death, Nobunaga waged a long campaign against Yoshitatsu and Tatsuoki, and throughout, he held up the banner of “Mino was bequeathed to me by the late Dosan.” When Nobunaga finally captured Inabayama Castle and conquered Mino in 1567, it was the fulfillment of Dosan’s eleven-year-old will.

After taking Mino, Nobunaga moved his base from Kiyosu in Owari to Inabayama in Mino, and renamed the city “Gifu.” The name derived from the Chinese legend of Mount Qi (Kizan), where King Wen of Zhou established his power before unifying the realm — a clear signal that Nobunaga’s full-scale “Tenka Fubu” (rule the realm by force) campaign was now beginning. The chain of succession that began at Nagaragawa — Dosan to Yoshitatsu to Tatsuoki to Nobunaga — proved to be the decisive prelude to Nobunaga’s national unification.

The Relationship Between Dosan and Nobunaga — The Meeting at Shotokuji

Dosan’s recognition of Nobunaga as a worthy successor did not happen suddenly on the eve of Nagaragawa. In April 1553, Dosan met Nobunaga at Shotokuji Temple in Tomida. At the time, Nobunaga was a young deputy governor of Owari widely dismissed as a “fool” (utsuke), but Dosan saw through to his true caliber. Shincho Koki records that Dosan predicted “All of my sons will end up serving Nobunaga.” The will written on the eve of Nagaragawa was the natural extension of the assessment Dosan had made three years earlier at Shotokuji.

The three Dosan wills are among the most important primary sources of the Sengoku period that have survived to today. Related documents are preserved at multiple sites, including Joinji Temple in Gifu City, and they remain valuable records of how power was actually transferred during the Sengoku era.

【Theory 6】Yoshitatsu’s Adoption of the Isshiki Name and His Claim to Toki Legitimacy

After killing his father, Yoshitatsu adopted the prestigious Isshiki surname — a branch of the Ashikaga family — and styled himself “Isshiki Sakyo-no-Taifu.” This has been read variously as an attempt to wash away the stain of patricide and as a calculated effort to bolster his own authority. It is a classic example of political performance in the Sengoku period.

Significance of the Isshiki Adoption

The Isshiki were one of the four “Shishiki” houses of the Muromachi shogunate (ranking just below the Kanrei houses) and traced their lineage to Seiwa Genji. For a parvenu daimyo in the Sengoku era, adopting the surname of an established noble house was an effective way to legitimize one’s authority. By becoming an “Isshiki,” Yoshitatsu sought to transform his self-image from “the son of the upstart Dosan” to “a legitimate daimyo of Ashikaga lineage.”

There was even a genealogical basis for the claim. According to Mino-no-Kuni Shoka Keifu, Yoshitatsu’s mother Miyoshino was descended from the Isshiki clan — her maternal grandfather was Isshiki Yoshito, the governor of Chita district in Owari (or alternatively, her father may have been Isshiki Yoshikiyo). If Miyoshino was of Isshiki descent, then Yoshitatsu had genuine bloodline justification for taking the Isshiki name.

Kinoshita Satoshi’s Interpretation

Sengoku historian Kinoshita Satoshi offers an interesting interpretation of why Yoshitatsu chose the Isshiki name. At the time, Toki Yorinori was still alive and had taken refuge with the Rokkaku clan. If Yoshitatsu had adopted the Toki name, it would have invited backlash from the Toki clan and possibly forced him to accept Yorinori’s return to Mino. On the other hand, choosing a name that wasn’t certain to provoke opposition (as the Rokkaku of neighboring Omi would have done) — and that ranked above the Toki — made the Isshiki “the politically optimal choice.”

Renaming of Retainers

There is also a theory that Yoshitatsu had his retainers adopt surnames connected to the Isshiki house. Former Toki retainers who had joined Yoshitatsu — the Kuwabara, Ando, Hineno, and Takenokoshi families — are said to have changed their surnames to Nobenaga, Iga, Ujiie, and Naruyoshi, respectively (names connected to Isshiki retainer families). However, the renaming likely took place after Yoshitatsu’s death, under the rule of Tatsuoki from 1561 onward, rather than during Yoshitatsu’s own lifetime.

Court Title

In 1558, Yoshitatsu received the court appointment of “Jibu-no-Taifu” (equivalent to Senior Fifth Rank, Lower Grade) from the imperial court. This title far exceeded Nobunaga’s at the time (Kazusa-no-Suke, Junior Sixth Rank, Upper Grade). The Jibu-no-Taifu position was traditionally granted to those of Seiwa Genji lineage, and Yoshitatsu’s acquisition of it signaled imperial recognition of his legitimacy as a “descendant of the Toki and member of the Isshiki house.”

Yoshitatsu’s adoption of the Isshiki name and acquisition of the Jibu-no-Taifu title are emblematic of Sengoku-era political performance. Far from being the “villainous son who killed his father” of popular imagination, Yoshitatsu was an able Sengoku daimyo who consolidated his rule of Mino through carefully constructed claims to legitimacy.

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A Strategic Analysis

Viewed strategically, the Battle of Nagaragawa concentrates the essential dynamics of power succession in the Sengoku period. Four points stand out.

First, the spiral of gekokujo. Dosan seized Mino from the Toki; Yoshitatsu seized Mino from Dosan. Power built through gekokujo is taken away by gekokujo — nowhere is the fragility of Sengoku power structures more vividly demonstrated than in this father-son confrontation. Because Dosan’s own claim to Mino was so weak, the framework of “Yoshitatsu rallies former Toki retainers and overthrows Dosan” became possible. What is gained through gekokujo is lost through gekokujo. Nagaragawa eloquently illustrates the cold logic of the Sengoku era.

Second, the link to Oda Nobunaga. The three wills of Dosan transformed the Battle of Nagaragawa from a private family conflict in Mino into a decisive prelude to Nobunaga’s national unification. For 11 years afterward, Nobunaga held up the justification of “I am Dosan’s appointed successor in Mino,” and finally in 1567 he captured Inabayama Castle and conquered Mino. He renamed the city Gifu and proclaimed “Tenka Fubu” — and the starting point of all of this was the Battle of Nagaragawa. The final flash of Dosan’s strategic vision laid the groundwork for Nobunaga’s unification campaign.

Third, the reassessment of Yoshitatsu. Long pigeonholed as “the villainous patricide” and “a mediocre daimyo,” Yoshitatsu has been undergoing rehabilitation in recent scholarship. He reorganized his retainer corps by absorbing former Toki loyalists, won the court title of Jibu-no-Taifu, legitimized his rule through the adoption of the Isshiki surname, and stabilized internal administration — none of which are accomplishments within reach of a mediocre lord. In just five years on the throne, Yoshitatsu firmly established his position as a Sengoku daimyo. As his father acknowledged with his dying words “Truly, the son of Dosan!” — Yoshitatsu’s abilities were in no way inferior to his father’s.

Fourth, Nagaragawa as the starting point for the careers of Akechi Mitsuhide and the Takenaka father-son pair. Among those who fought on Dosan’s side at Nagaragawa were several future leading figures of late Sengoku history. Akechi Mitsuhide’s exile in Echizen and his eventual meeting with Nobunaga; the rise of Takenaka Hanbei as Hideyoshi’s master strategist; Saito Toshiharu’s incorporation into the Oda army — all of these histories trace back to the Battle of Nagaragawa. As a hinge point in the historical chain, Nagaragawa occupies a unique position in Sengoku history.

In Kunitori Monogatari, Shiba Ryotaro depicted Dosan as “the Viper of Mino” and celebrated his life of gekokujo as the symbol of the Sengoku era. But Dosan’s own end was, with crushing irony, brought about by the very logic of gekokujo he had embodied: he was killed by his own son. “The realm of Saito Dosan was won not at Nagaragawa, but in Nobunaga.” The foundation Dosan built — the province of Mino — passed through his son’s hands and was finally transmuted by his son-in-law Nobunaga into the springboard for national unification. The Battle of Nagaragawa stands as a rare battle that simultaneously demonstrates the cold logic of the Sengoku era and the marvelous chain of historical causation.

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Famous Sayings and Quotations from the Battle

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Anecdotes and Episodes

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Timeline of the Battle of Nagaragawa

Date	Event
Daiei 7 (1527)	Birth of Saito Yoshitatsu. His mother was Miyoshino (various accounts)
Tenbun 11 (1542)	Dosan expels Toki Yorinori to Owari and seizes the position of provincial lord of Mino
c. Tenbun 17 (1548)	Dosan and Oda Nobuhide make peace. Dosan’s daughter Kicho (Nohime) marries Nobunaga
Tenbun 17 (1548)	Dosan turns over Inabayama Inokuchi Castle to Yoshitatsu and retires to Sagiyama Castle (de facto succession)
Tenbun 22 (1553) April	Dosan and Nobunaga meet at Shotokuji Temple in Tomida. Dosan recognizes Nobunaga’s caliber
Tenbun 23 (1554)	Dosan formally cedes clan headship to Yoshitatsu and retires
Koji 1 (1555) November	Yoshitatsu feigns illness, lures brothers Magoshiro and Kiheiji to his residence, and has Hineno Hironari kill them. Dosan flees to Ogura Castle
Koji 1 (1555) December	Yoshitatsu issues an edict at Mieji Temple under the name “Hanka” (declaration of intent to kill Dosan)
Koji 2 (1556) April 18	Dosan advances his army to Mount Tsuruyama north of Inabayama Castle. About 2,700 local lords rally to him
April 19	Dosan prepares three wills for Nobunaga. He bequeaths Mino Province to Nobunaga
April 20, morning	The Battle of Nagaragawa begins. Yoshitatsu’s 17,500-man army crosses the Nagaragawa River to attack
April 20	Opening engagement: Dosan repels Yoshitatsu’s vanguard under Takenokoshi Dochin and kills Takenokoshi
April 20	Yoshitatsu personally leads his elite guard across the river. Single combat between Shibata Kakunai and Nagaya Jinemon
April 20	Yoshitatsu orders a full charge. Dosan’s army collapses. Dosan is killed by Nagai Michikatsu and Komaki Genta. Age 63
April 20, same day	Nobunaga advances to Toshima and Tozobo at Daira to attempt rescue, but retreats upon learning of Dosan’s death
Late April	Yoshitatsu’s forces attack Akechi Castle. Akechi Mitsuyasu commits seppuku; young Akechi Mitsuhide escapes into wandering
Koji 4 (1558)	Yoshitatsu receives the court title of Jibu-no-Taifu. Adopts the Isshiki surname
Eiroku 3 (1560) April 8	Issuance of the “Rokkaku Shotei Jojo Utsushi,” denouncing the crimes of Dosan and Yoshitatsu
Eiroku 4 (1561) May	Yoshitatsu dies suddenly at age 34. His heir Tatsuoki (age 14) succeeds him
Eiroku 10 (1567)	Nobunaga defeats Tatsuoki at the Battle of Inabayama Castle. Conquers Mino and renames it “Gifu”
Tensho 1 (1573) August	Saito Tatsuoki is killed at the Battle of Tonezaka. The Saito clan of Mino is extinguished (three generations from Dosan)

* Dates are in the old lunar calendar. Background colors: yellow = major events; red = battles and deaths in combat

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Key Figures on Both Sides

Eastern Army (Dosan’s Forces, approx. 2,700)

Role	Figure	Description
Commander-in-Chief	Saito Dosan	Age 63. “The Viper of Mino.” Deployed at Mount Tsuruyama. Killed by Nagai Michikatsu and Komaki Genta
Dosan’s son	Saito Toshitaka	Dosan’s son (half-brother of Yoshitatsu). Fought with his father on Mount Tsuruyama; later took refuge with the Oda
Dosan’s son	Saito Toshiharu	Dosan’s son. Younger brother of Nohime. After the battle inherited the Saito of Mino lineage within the Oda household. Killed at the Honnoji Incident
Akechi clan	Akechi Mitsuyasu	Akechi Mitsuhide’s uncle. Lord of Akechi Castle. Fought on Dosan’s side at Nagaragawa; committed seppuku when Akechi Castle fell
Akechi clan	Akechi Mitsuhisa	Senior retainer of the Akechi clan. Fought on Dosan’s side
Akechi clan	Akechi Mitsuhide	Approximately 28 years old. Fought alongside his uncle Mitsuyasu. After the battle wandered as a ronin before entering Nobunaga’s service
Dosan’s retainer	Takenaka Shigemoto	Father of Takenaka Hanbei. Fought on Dosan’s side. Forerunner of the Takenaka clan that would serve Nobunaga and Hideyoshi
Dosan’s retainer	Shibata Kakunai	Won the single-combat duel against Nagaya Jinemon of Yoshitatsu’s army. Embodied the fighting spirit of Dosan’s troops
Relief force	Oda Nobunaga	Age 22. Dosan’s son-in-law. Advanced to Daira to attempt rescue, but withdrew after the battle ended

Western Army (Yoshitatsu’s Forces, approx. 17,500)

Role	Figure	Description
Commander-in-Chief	Saito Yoshitatsu	Age 30. Dosan’s eldest son. Personally led his elite guard across the river and won. Became lord of Mino after the battle
Uncle / Advisor	Nagai Michitoshi	Dosan’s younger brother (or older brother by concubine), Yoshitatsu’s uncle. Conspired with Yoshitatsu in the killing of his brothers
Vanguard	Takenokoshi Dochin	Vanguard commander on Yoshitatsu’s side. Led the river crossing; killed by Dosan
Yoshitatsu’s retainer	Hineno Hironari	Executed the killing of Yoshitatsu’s brothers in November 1555. Fought on Yoshitatsu’s side
Killed Dosan	Nagai Michikatsu	First to thrust a spear into Dosan and slice off his nose. Had intended to capture him alive
Killed Dosan	Komaki Genta	Swept Dosan’s leg at the shin and took his head. The outcome differed from the original plan
Single combat	Nagaya Jinemon	Issued the formal challenge for single combat from Yoshitatsu’s side; killed by Shibata Kakunai
Yoshitatsu’s side	Inaba Ittetsu (Yoshimichi)	One of the Three Heroes of Western Mino. Fought on Yoshitatsu’s side, later defected to Nobunaga during Nobunaga’s conquest of Mino
Yoshitatsu’s side	Ando Morinari	One of the Three Heroes of Western Mino. Fought on Yoshitatsu’s side
Yoshitatsu’s side	Ujiie Naomoto	One of the Three Heroes of Western Mino. Fought on Yoshitatsu’s side

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Historic Sites Map & Travel Guide

Related Historic Sites Map — Battle of Nagaragawa

Sites on the Map:

• Dosan Mound (grave) — Tomb of Saito Dosan. Relocated several times due to flooding of the Nagaragawa River; currently at Nagara Fukumitsu in Gifu City
• Joinji Temple (temple) — Family temple of the Saito clan. Houses portraits of Dosan and Yoshitatsu and related historical materials
• Gifu Castle (Inabayama Castle) (castle) — Home base of three generations of the Saito clan: Dosan, Yoshitatsu, and Tatsuoki
• Ogura Castle Ruins (castle) — Castle where Dosan took refuge after the murder of his sons. Old Toki stronghold
• Battlefield of Moribe (battlefield) — Site of the 1561 battle between Nobunaga and Yoshitatsu/Tatsuoki

* This map shows modern roads for reference. Roads and terrain during the Sengoku period would have been different. The exact location of Mount Tsuruyama is disputed in primary sources, but the area around Sofukuji Temple is generally identified as the most likely site.

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

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Model Itinerary — Tracing the Footsteps of Dosan and His Son in One Day

Trip Details

• Duration: Approximately 5–6 hours (by car)
• Walking pace: Approximately 4 km/h; time at each site: 30–60 minutes
• Starting point: Within 10 minutes by car from JR Gifu Station

Itinerary

① Joinji Temple (Approx. 60 minutes)
Family temple of the Saito clan. Portraits of Dosan and Yoshitatsu and edict documents are on display. Admission 200 yen.
– By car: About 10 minutes from JR Gifu Station

② Dosan Mound (Approx. 20 minutes)
Tomb of Saito Dosan. Located in a residential area with limited signage; a 5-minute walk from Joinji.
– On foot: About 5 minutes from Joinji

③ Gifu Castle (Inabayama Castle) (Approx. 90 minutes)
Home base of three generations of the Saito clan. Ropeway access to the summit. The castle includes a museum.
– By car: About 10 minutes from Dosan Mound

④ Mount Tsuruyama area (Sofukuji Temple) (Approx. 30 minutes)
The likely site of Dosan’s battle deployment at Mount Tsuruyama. Sofukuji is also a temple dedicated to Nobunaga and his heir Nobutada.
– By car: About 10 minutes from the Gifu Castle ropeway station

⑤ Ogura Castle Ruins (Approx. 90 minutes, for the hearty)
The castle where Dosan took refuge. Hiking trail to the summit; the observation deck offers a panoramic view of the Mino plain.
– By car: About 40 minutes from Gifu Castle

⑥ Battlefield of Moribe (Approx. 20 minutes, optional)
Site of the 1561 battle five years after Nagaragawa, where Nobunaga fought Yoshitatsu and Tatsuoki. Also known as the battle that launched Maeda Toshiie’s career.
– By car: About 60 minutes south of Ogura Castle

Customize Your Visit

• Two-day trip: Day one in Gifu City (Joinji, Dosan Mound, Gifu Castle, Mount Tsuruyama); day two extending to Yamagata City (Ogura Castle) and Anpachi District (Battlefield of Moribe) — tracing the path of Dosan and his son
• For Dosan fans: The “Life of Dosan” course — Joinji + Dosan Mound + Gifu Castle + Ogura Castle
• For a relaxed visit: Half-day course covering Joinji + Dosan Mound + Gifu Castle
• For Sengoku enthusiasts: Gifu Castle + Battlefield of Moribe + Inabayama Castle (Nobunaga’s conquest of Mino) + Komakiyama Castle — tracing Sengoku history from Mino to Owari

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Related Articles

Battle Articles

• Battle of Okehazama (1560) — Four years after Nagaragawa, the battle that launched Nobunaga’s quest to rule the realm
• Battle of Inabayama Castle (1567) — Nobunaga defeats Tatsuoki and conquers Mino — the fulfillment of Dosan’s will
• Battle of Anegawa (1570) — A key battle on Nobunaga’s path to national unification
• Honnoji Incident (1582) — Akechi Mitsuhide strikes down Nobunaga: the destination of the story that began at Nagaragawa

Warlord Articles

• Saito Dosan — “The Viper of Mino.” Killed by his own son Yoshitatsu at Nagaragawa
• Saito Yoshitatsu — Dosan’s eldest son. Killed his father and became lord of Mino but died at age 34
• Oda Nobunaga — Dosan’s son-in-law. Failed to relieve Dosan in time, but later conquered Mino himself
• Oda Nobuhide — Nobunaga’s father. Long an adversary of Dosan before peace made them in-laws
• Akechi Mitsuhide — Fought on Dosan’s side. Wandered after the battle before entering Nobunaga’s service — and the path to Honnoji
• Takenaka Hanbei — His father Shigemoto fought on Dosan’s side. Later became Hideyoshi’s master strategist

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References

Primary Sources

• Ota Gyuichi, Shincho Koki — Records Dosan’s death in detail
• Ota Gyuichi, Daikosama Gunki no Uchi — Records Dosan’s final words “Truly, the son of Dosan!”
• Oze Hoan, Hoan Shincho Ki — Early Edo period account, summary of the Nagaragawa engagement
• Konoki — Records the relationship between Yoshitatsu and Dosan
• Mieji Monjo — Edict by Yoshitatsu under the name “Hanka” (December 1555)
• “Rokkaku Shotei Jojo Utsushi” (April 8, 1560) — Contemporary source denouncing the crimes of Dosan and Yoshitatsu
• Three Wills of Dosan (April 19, 1556) — Deeds of cession to Nobunaga

Academic Works

• Yokoyama Sumio, “The Two Renunciations of Saito Dosan,” Gifu Shigaku No. 77, 1983 — Foundation for the two-generation conquest theory
• Maruyama Kotaro, “On the Rokkaku Shotei Jojo of 1560,” Gifu Shigaku No. 72, 1980
• Yokoyama Sumio, “The Documents of Toki Yoritake and His Term as Mino Provincial Governor,” Gifu Shigaku No. 80, 1986
• Kinoshita Satoshi, The Four Generations of the Saito Clan (Studies of Sengoku Daimyo Families), Minerva Shobo, 2020
• Katsumata Shizuo, “The Rise and Fall of the Saito Clan of Mino,” Gifu-ken Shi Tsushi-hen: Primitive, Ancient, and Medieval, Gifu Prefecture, 1980
• Kuwata Tadachika, Saito Dosan, Shinjinbutsu Oraisha
• Taniguchi Katsuhiro, Biographical Dictionary of Nobunaga’s Retainers, Yoshikawa Kobunkan, 2010
• Tsuchiyama Kohito, “A Preliminary Study of the Chronology and Related Sources of Dosan’s Documents,” Special Exhibition: From Dosan to Nobunaga, Gifu City Museum of History, 2006

Published Papers

• Okuda Hisashi, “The Tale of Saito Dosan and Yoshitatsu in the Printed Edition of Tensho Gunki: A Case Study of Narrative Reception and Transformation,” Annual Report of the Department of Asian Studies No. 4, Faculty of International Liberal Arts, Otemon Gakuin University, 2011
• Suzuki Hideo, “The Forgotten Sengoku Culture of Mino: The Refinement of Saito Dosan,” Local Studies of Gifu No. 76, 1997

Public Resources

• Gifu City Museum of History, exhibition catalog “From Dosan to Nobunaga”
• Gifu City official tourism guide, “Historic Sites Related to Saito Dosan and Yoshitatsu”
• Joinji Temple (family temple of the Saito clan) official guide
• Yamagata City official guide, “Ogura Castle Ruins”
• Gifu City, official information on “Gifu Castle and Gifu Park”

* This article is based on the historical sources, academic works, and papers listed above, as well as multiple other references. Historical interpretation is a subject of ongoing scholarly debate, and established views may change as new sources are discovered or research advances.