Bio Azai Nagamasa (1545-1573)

Although his domain was relatively small compared with those of the great warlords of the age, Nagamasa transformed the Azai into one of the leading military powers of northern Ōmi. His resistance to Nobunaga eventually ended with the destruction of the Azai clan and his death during the siege of Odani Castle in 1573. Through his daughters, Yodo-dono (淀殿, 1569–1615), Ohatsu (初, 1570–1633), and Oeyo or Gō (江, 1573–1626), however, his bloodline became closely intertwined with both the Toyotomi and Tokugawa dynasties, ensuring his lasting influence on Japanese history.

Early life

Nagamasa was born in 1545 (Tenbun 14), probably in or near Kannonji Castle (観音寺城) in southern Ōmi, where his father, Azai Hisamasa (浅井久政, 1526–1573), was then residing. The castle served as the principal stronghold of the Rokkaku clan (六角氏), the military rulers of southern Ōmi. His childhood name was Saruyashamaru (猿夜叉丸), also recorded simply as Saruyasha (猿夜叉).

At the time, the Azai had already emerged as the dominant military house in northern Ōmi after displacing their former overlords, the Kyōgoku clan (京極氏). Their fortunes, however, had declined after defeats at the hands of the Rokkaku, forcing Hisamasa to acknowledge Rokkaku overlordship to preserve the clan's remaining territory. According to later tradition, the young Nagamasa and his mother, Ono-dono (小野殿), were even held as hostages by the Rokkaku, although contemporary evidence for this remains uncertain. Hisamasa maintained the Azai domain through a policy of accommodation with the Rokkaku, but many retainers opposed this cautious approach and resented the declining influence of veteran warriors who had served under Nagamasa's grandfather, Azai Sukemasa (浅井亮政, 1491–1542).

In the first month of 1559 (Eiroku 2), at the age of fifteen, he underwent his coming-of-age ceremony (genpuku). As a sign of the Azai clan's subordinate status, he received the character 賢 from the name of Rokkaku Yoshikata (六角義賢, 1521–1598) and adopted the adult name Katamasa (賢政). Around the same time, he married a daughter of Hirai Sadatake (平井定武), one of the Rokkaku's senior retainers. Both the new name and the marriage reflected the political realities of the day and reinforced the Azai's ties to their powerful southern overlords.

The situation changed rapidly. Within months, Katamasa divorced his wife and returned her to the Hirai family, an unmistakable declaration that the Azai intended to break free from Rokkaku influence. The decision led directly to renewed conflict between the two houses. Later chronicles portray the move as one made against Hisamasa's wishes, but surviving contemporary documents suggest that father and son continued to cooperate closely during this period.

In 1560, Katamasa made his battlefield debut at the Battle of Norada (野良田の戦い). Although only sixteen years old, he commanded the Azai army against the numerically superior forces of the Rokkaku and achieved a decisive victory. The battle marked a turning point in the history of northern Ōmi. Rather than simply reflecting youthful brilliance, modern historians point to careful preparations already underway before Hisamasa's retirement, together with growing weaknesses within the Rokkaku administration. The victory restored the Azai clan's independence and greatly enhanced the prestige of the young commander.

Later that year, Hisamasa retired, probably under pressure from influential retainers who favoured a more assertive policy towards the Rokkaku. Katamasa succeeded as head of the Azai clan. However, Hisamasa continued to participate in government and appears alongside his son in surviving documents, suggesting that authority remained shared for some time rather than passing abruptly to the next generation.

Following the victory at Norada and the restoration of the Azai's independence, Katamasa changed his name to Nagamasa (長政), probably around 1560 or 1561. The change marked the end of the Azai's formal subordination to the Rokkaku, whose character 賢 he abandoned. Older accounts claimed that Oda Nobunaga bestowed the character 長 after their later alliance, but modern scholarship generally rejects this interpretation, as Nagamasa had already adopted the name before the alliance was concluded and the two daimyō were political equals rather than lord and vassal.

Rise of the Azai clan

Nagamasa's accession coincided with a period of instability among the neighbouring powers. While the Azai were consolidating their position in northern Ōmi, the Rokkaku clan became increasingly divided. In 1563, the Rokkaku's chief retainer, Gotō Katatoyo (後藤賢豊, 1506–1563), was killed on the orders of Rokkaku Yoshiharu (六角義治, 1545–1612) during the Kannonji Incident (観音寺騒動). The resulting political turmoil prompted several experienced retainers to abandon the Rokkaku and enter Azai service, accelerating the decline of their former masters. Taking advantage of the situation, Nagamasa expanded his authority into central Ōmi, issuing orders of protection to Taga Taisha (多賀大社) and confirming the estates of local temples. By the mid-1560s, the Azai had become the dominant military power in northern Ōmi, while the Rokkaku were steadily losing influence.

Unlike many Sengoku warlords who relied primarily on conquest, Nagamasa also strengthened his rule through cooperation with the network of local warrior families that formed the political foundation of northern Ōmi. His administration remained rooted in these provincial alliances rather than the more centralised systems that figures such as Oda Nobunaga would later establish. This difference in political outlook would become increasingly significant as Nobunaga's ambitions expanded beyond regional dominance.

Alliance with Oda Nobunaga

During the mid-1560s, Nobunaga was engaged in a prolonged struggle against the Saitō clan (斎藤氏) of Mino Province. Seeking to secure his northern flank and gain a reliable route towards Kyōto, he approached Nagamasa with a proposal for an alliance. The negotiations were conducted through the retainer Fuwa Mitsuharu (不破光治, d. 1570), and, as was customary, the agreement was sealed by marriage.

The marriage united Nagamasa with Nobunaga's younger sister Oichi. The exact date remains uncertain and has long been debated by historians. Contemporary and later sources place the wedding anywhere between 1561 and 1568, with modern scholarship generally favouring a date in the latter half of the decade. Regardless of the precise year, the marriage represented one of the most important political alliances of the period. It linked two rising military houses whose territories controlled the strategic corridor between Owari, Mino and the imperial capital.

Older tradition holds that Nagamasa accepted the alliance only after Nobunaga promised never to attack the Asakura clan (朝倉氏), long regarded as the Azai's allies. This story became deeply rooted in popular history and later literature. Modern historians, however, are far more cautious. Some argue that there is no contemporary evidence for such a pledge, while others suggest that the relationship between the Azai and Asakura was more complex than a simple military alliance, perhaps resembling a loose overlord-vassal relationship established after the Azai gained independence from the Rokkaku. The exact nature of the agreement therefore remains one of the principal controversies surrounding Nagamasa's career.

The alliance nevertheless proved highly beneficial to both sides. Nobunaga secured the eastern approach to Kyōto and strengthened his position for the conquest of Mino, while Nagamasa gained a powerful ally against the weakening Rokkaku. According to later tradition, Nobunaga was so pleased by the arrangement that he paid the entire cost of the wedding himself, an unusual gesture at the time. Some sources also claim that Nagamasa adopted the character naga (長) from Nobunaga's name upon the marriage, although this interpretation is disputed by modern scholarship.

In 1568 the alliance bore immediate fruit when Nobunaga marched to Kyōto in support of Ashikaga Yoshiaki (足利義昭, 1537–1597), who was installed as the fifteenth and last shōgun of the Muromachi shogunate. Nagamasa joined the campaign through Ōmi, helping to secure the route to the capital while the Rokkaku retreated before Nobunaga's advance. Although several of Nobunaga's principal followers received rewards after the successful campaign, there is no surviving record of a comparable grant to Nagamasa. Historian Owada Tetsuo has suggested that this apparent slight may have contributed to the gradual cooling of relations between the two allies, though the evidence remains circumstantial.

Break with Nobunaga

The alliance between the Oda and Azai families lasted only a few years before collapsing dramatically. In the spring of 1570, Nobunaga launched a campaign into Echizen Province against Asakura Yoshikage (朝倉義景, 1533–1573), who had refused repeated requests to support Ashikaga Yoshiaki's government in Kyōto. Advancing with Tokugawa Ieyasu (徳川家康, 1543–1616), Nobunaga captured several frontier castles and pushed deep into Asakura territory.

For Nagamasa, the campaign created an impossible political dilemma. His wife was Nobunaga's sister, yet the Asakura had long been among the Azai's closest allies and, according to one interpretation, may even have enjoyed a superior status in relation to the Azai after the clan freed itself from Rokkaku control. Faced with choosing between family ties and longstanding political obligations, Nagamasa ultimately turned against Nobunaga. While the Oda army was operating around Kanegasaki (金ヶ崎), Azai forces attacked from the rear, forcing Nobunaga into a hurried withdrawal through the mountains of Ōmi in what became known as the Battle of Kanegasaki (金ヶ崎の戦い). The successful retreat, traditionally attributed to the rearguard actions of Kinoshita Hideyoshi—later Toyotomi Hideyoshi (豊臣秀吉, 1537–1598)—and Akechi Mitsuhide (明智光秀, 1528–1582), prevented what might otherwise have been a disastrous defeat for Nobunaga.

Why Nagamasa abandoned the alliance has remained one of the enduring controversies of Sengoku history. For centuries the accepted explanation was that Nobunaga had violated a promise never to attack the Asakura, leaving Nagamasa honour-bound to defend them. Modern scholarship is less certain. Some historians argue that no contemporary source confirms such a pledge. In contrast, others believe Nagamasa feared that the destruction of the Asakura would leave the Azai isolated as Nobunaga's next target. Another interpretation emphasises the changing political relationship between the two men, suggesting that Nobunaga increasingly treated Nagamasa as a subordinate rather than an equal ally.

Others point to evidence that the Azai, Asakura and the exiled Rokkaku coordinated their actions under the encouragement of Shōgun Ashikaga Yoshiaki as part of a broader effort to contain Nobunaga's growing power. It has also been argued that Nagamasa's regional style of rule, based on local warrior families, was fundamentally incompatible with Nobunaga's increasingly centralised vision of authority. None of these explanations has achieved universal acceptance, and the reasons for Nagamasa's decision remain debated.

Battle of Anegawa

The rupture soon led to open war. In the summer of 1570, Nobunaga and Tokugawa Ieyasu invaded northern Ōmi with an army estimated at between 20,000 and 30,000 men. Nagamasa called upon the Asakura for assistance, and they responded with a force that brought the allied army to roughly 15,000–20,000 troops. The two armies met near the Anegawa River (姉川) in one of the best-known battles of the Sengoku period.


The fighting was intense. Nobunaga personally confronted the Azai forces, while Ieyasu engaged the Asakura contingent. Contemporary accounts suggest that the Azai fought with exceptional determination and at one stage may even have been gaining the upper hand despite facing superior numbers. The battle turned only after part of the Tokugawa army wheeled into the Azai flank, forcing Nagamasa's troops to withdraw. Although Nobunaga and Ieyasu claimed victory, the result was less decisive than later tradition often suggests. Their army soon withdrew, leaving the Azai and Asakura still capable of continuing the war.

The conflict nevertheless widened rapidly. During the following months, the Azai and Asakura joined other opponents of Nobunaga, including the Miyoshi faction (三好三人衆), militant leagues of the Honganji (本願寺), and later Enryaku-ji (延暦寺) on Mount Hiei, in what became known as the "anti-Nobunaga coalition" or Nobunaga Encirclement (信長包囲網). In September 1570, the allied forces again threatened Nobunaga during the Siege of Shiga (志賀の陣), inflicting heavy casualties, including the death of the veteran Oda retainer Mori Yoshinari (森可成, 1523–1570). Nobunaga temporarily defused the crisis through negotiations brokered by the imperial court and Ashikaga Yoshiaki, but the peace proved short-lived.

The Nobunaga Encirclement

Although the Battle of Anegawa failed to halt Nobunaga's advance, the Azai remained one of the principal pillars of the anti-Nobunaga coalition. During the next three years, Nagamasa continued to resist repeated Oda offensives while coordinating with the Asakura, militant Buddhist forces, and other regional opponents. Rather than a single alliance directed by one leader, the coalition consisted of several independent powers united by a common determination to curb Nobunaga's expanding influence.

In 1571 the balance shifted further in Nobunaga's favour. Enryaku-ji (延暦寺), whose warrior monks had cooperated with the Azai and Asakura, was destroyed during Nobunaga's assault on Mount Hiei (比叡山焼き討ち). The elimination of this influential religious centre deprived the coalition of an important ally and demonstrated Nobunaga's willingness to use overwhelming force against both secular and religious opponents.

Despite these setbacks, Nagamasa continued the struggle. In the summer of 1572, Nobunaga again invaded northern Ōmi, prompting Nagamasa to request military assistance from Asakura Yoshikage. The Asakura responded with an army said to number around 15,000 men, but neither side sought a decisive engagement, and the opposing forces remained in a tense standoff. The Azai and Asakura still faced a numerical disadvantage, and the strategic situation continued to deteriorate.

A significant change came in the autumn of that year when Takeda Shingen (武田信玄, 1521–1573), responding to appeals from Shōgun Ashikaga Yoshiaki, finally marched west from Kai Province. Shingen informed both Nagamasa and Hisamasa that he intended to begin operations without delay, raising hopes that the combined pressure of the Takeda, Azai and Asakura might overwhelm Nobunaga. Those expectations appeared justified after Shingen's victory over the Oda-Tokugawa alliance at the Battle of Mikatagahara (三方ヶ原の戦い) in December 1572.

The opportunity was squandered. While Shingen continued his advance, the Asakura army withdrew from northern Ōmi, citing heavy snowfall and exhausted troops. Contemporary sources record that Shingen was furious at Yoshikage's decision and urged him to resume the campaign, but his appeals were ignored. Before a renewed offensive could be mounted, Shingen died suddenly in the spring of 1573. His death effectively shattered the coalition's military strategy and allowed Nobunaga to concentrate his full strength against his remaining enemies in Ōmi and Echizen.

Fall of the Azai clan

In July 1573, Nobunaga launched the campaign that would bring the Azai to an end. Leading an army reportedly numbering around 30,000 men, he advanced once more into northern Ōmi. Nagamasa appealed to Asakura Yoshikage for assistance, and the Asakura responded with a force of approximately 20,000 troops. By this stage, however, the strategic balance had become irreversible. Oda forces rapidly captured a series of outlying fortifications, while defections among the Azai retainers steadily weakened Nagamasa's position. Recognising that relief was no longer possible, Yoshikage retreated towards Echizen. Nobunaga pursued him relentlessly, annihilating the retreating army at the Battle of Tōnezaka (刀根坂の戦い) before invading Echizen itself. The Asakura clan was destroyed with the fall of Ichijōdani (一乗谷), leaving the Azai isolated.

Nobunaga then returned to northern Ōmi and invested Odani Castle. Envoys, including Fuwa Mitsuharu, who had helped negotiate the original Oda-Azai alliance, and later Hashiba Hideyoshi, urged Nagamasa to surrender. He refused every offer. With no realistic prospect of relief, he chose to defend the castle to the end.

On 27 August 1573, Hisamasa committed suicide. Nagamasa continued the defence for several more days before taking his own life on 1 September 1573, aged twenty-nine. Earlier sources placed his death on 28 August, but the discovery of a letter of commendation written by Nagamasa after that date has established 1 September as the correct date. Interestingly, the document continued to use the era name Genki (元亀) rather than Tenshō (天正), the new era proclaimed under Nobunaga's authority. Some historians interpret this as a final symbolic act of defiance. Nagamasa was buried at Tokushō-ji (徳勝寺) in present-day Nagahama, Shiga Prefecture.

Before his death, Nagamasa entrusted Oichi and their daughters to Nobunaga. According to later accounts, Nobunaga subsequently persuaded Oichi to reveal the whereabouts of their young son Manpukumaru (万福丸), promising to raise the boy. Instead, the child was executed on Hideyoshi's orders, apparently without Oichi's knowledge. Whether every detail of this episode is historically accurate remains uncertain, but it reflects the bitterness that marked the final destruction of the Azai house.



The fate of Nagamasa's remains became the subject of one of the most enduring stories surrounding Nobunaga. Contemporary chronicles state that the skulls of Nagamasa, Hisamasa and Asakura Yoshikage were cleaned, lacquered and displayed during a New Year gathering in 1574. Later tradition transformed this episode into the famous tale that Nobunaga fashioned them into drinking cups. Modern historians generally reject this embellishment. While the skulls were almost certainly exhibited as trophies, there is no reliable contemporary evidence that Nobunaga ever drank from them.

Legacy

Although Azai Nagamasa ruled northern Ōmi for little more than a decade, he remains one of the most admired daimyō of the Sengoku period. Contemporary and later sources consistently describe him as an able commander who earned the loyalty of his retainers through personal courage and military skill. His victory over the Rokkaku at the Battle of Norada established the Azai as the dominant power in northern Ōmi. At the same time, his determined resistance to Nobunaga made him one of the principal figures of the anti-Nobunaga coalition.

At the same time, Nagamasa's reputation has long been shaped by his decision to turn against his brother-in-law. Edo-period chronicles often portrayed him as the model of loyalty, sacrificing his own house rather than abandoning the Asakura clan. Modern historians take a more nuanced view. Rather than attributing his actions solely to personal honour or a promise not to attack the Asakura, they point to a combination of political, military and strategic considerations. The precise reasons for his decision remain uncertain, reflecting the fragmentary nature of the surviving sources.

Nagamasa's influence outlived the destruction of the Azai clan through his three daughters with Oichi. The eldest, Yodo-dono (淀殿, 1569–1615), became the principal consort of Toyotomi Hideyoshi and the mother of Toyotomi Hideyori (豊臣秀頼, 1593–1615), the last major representative of the Toyotomi house. The second daughter, Ohatsu (初, 1570–1633), married Kyōgoku Takatsugu (京極高次, 1563–1609), strengthening the position of the Kyōgoku family during the transition from Toyotomi to Tokugawa rule. The youngest, Oeyo or Gō (江, 1573–1626), became the wife of Tokugawa Hidetada (徳川秀忠, 1579–1632), the second Tokugawa shōgun, and the mother of Tokugawa Iemitsu (徳川家光, 1604–1651), the third shōgun. Through these marriages, Nagamasa became a direct ancestor of both the Toyotomi heir and the Tokugawa shogunal line, giving the defeated Azai family an enduring place in Japanese political history.

This dynastic connection was formally recognised during the Edo period. In 1632, after Iemitsu had assumed the shogunate, Nagamasa was posthumously awarded the court rank of Junior Third Rank (従三位) and the title of Gon-Chūnagon (権中納言). The honour reflected his status as the maternal grandfather of the Tokugawa dynasty rather than any reassessment of his role in the Sengoku conflicts.

Today, the ruins of Odani Castle in Nagahama, Shiga Prefecture, are preserved as a National Historic Site. The extensive mountain fortress, once regarded as one of the strongest castles in northern Ōmi, remains closely associated with Nagamasa and the final stand of the Azai clan. His story continues to appear in historical fiction, television dramas and popular histories, where he is often portrayed as a tragic figure caught between family ties, political necessity and personal conviction. While the details of some famous episodes remain disputed, there is little disagreement that Azai Nagamasa was one of the most capable regional daimyō of his generation and a central figure in the struggles that paved the way for the unification of Japan.

Links:

• Azai Nagamasa (浅井長政の歴史). From Japanese Wikipedia.
• Asai Nagamasa no Rekishi. From Touken World.

References:

• Berry, Mary Elizabeth, Hideyoshi, Harvard University Press, 1982.
• Elisonas, Jurgis, "The Unification of Japan", in John Whitney Hall (ed.), The Cambridge History of Japan, Vol. 4: Early Modern Japan, Cambridge University Press, 1991.
• Hall, John Whitney; Nagahara, Keiji & Yamamura, Kozo (eds.), Japan Before Tokugawa: Political Consolidation and Economic Growth, 1500–1650, Princeton University Press, 1981.
• Owada, Tetsuo (小和田哲男), Ōmi Azai-shi no Kenkyū (近江浅井氏の研究), Yoshikawa Kōbunkan, 2008.
• Turnbull, Stephen, The Samurai Sourcebook, Cassell, 1998.
• Turnbull, Stephen, War in Japan 1467–1615, Osprey Publishing, 2002.