By the summer of 1556, Oda Nobunaga no longer appeared to be the eccentric “great fool of Owari.” Four years earlier, in 1552, having just assumed the position of clan leader, he managed to defend his position: first in the Battle of Akatsuka, and then at Kayazu Fort. In 1553, together with his western neighbor and ally Saito Dosan, his father-in-law, Nobunaga successfully repelled an attack by the Imagawa clan on the border fort of Muraki. In 1554, he united his own branch of the family with the Kiyosu line. Step by step, the young military leader strengthened his position.
But much more severe trials awaited him ahead. In 1556, Nobunaga's relationship with his younger brother Nobukatsu (1536–1557) finally came to a head. Most of the clan elders sided with Nobukatsu, including the most influential of them, Hayashi Hidesada. There is a theory that it was Hidesada who was behind this conspiracy, hoping to turn Nobukatsu into an obedient puppet, unlike the wayward and independent Nobunaga. It is important to remember that this was already his second attempt to depose Nobuhide's eldest son — he had made his first attempt back in 1552.
At some point, Nobukatsu began to behave like the head of the clan. For Nobunaga, this was a clear signal that a coup was being prepared. He gathered his loyal warriors around him and prepared for battle.
On August 24, 1556, the decisive battle took place in Inogahara, just five kilometers east of Kiyosu Castle. Those familiar with 16th-century Japanese history know about the famous Battle of Okehazama, where Nobunaga, with fewer forces, defeated the powerful Imagawa Yoshimoto. However, few remember that Nobunaga began to master the art of striking precisely at the enemy's weak points much earlier — in battles for the unification and strengthening of his clan.
In the Battle of Inogahara, the older generation almost unanimously supported Nobukatsu, which made Nobunaga's position extremely dangerous. The battle began around noon when a detachment of a thousand warriors under the command of Shibata Katsuie attacked Nobunaga's positions. But numerical superiority was not decisive. The fighting spirit of Nobukatsu's warriors was weak: many did not understand why they were fighting against the legitimate head of the clan. According to the description of the family chronicler Ota Gyuichi, Nobunaga loudly berated the traitors with fierce insults during the battle. His commanding voice, which they were accustomed to obeying, finally broke their resolve. Katsuiye's warriors began to slow down their advance and soon fled altogether.
But the battle did not end there. The second part of the battle unfolded a little further south, where Nobunaga's army clashed with a detachment commanded by Hayashi Mimasaka, Hidesada's younger brother. According to Ota Gyūichi, the battle began with a duel between the commanders. Kuroda Hambay faced Mimasa, but he was defeated and lost his left arm. At this critical moment, Nobunaga himself saved the situation: according to one version, he replaced his fallen vassal and personally entered the fray, according to another, he unexpectedly attacked and defeated Mimasa. Seeing the death of their commander and Nobunaga's furious curses, the enemy troops lost what little courage they had left and fled in disorder. Thus, with only 700 soldiers against a much larger army, Nobunaga won the battle of Inogahara.
A few days later, Nobunaga's mother met with her eldest son and persuaded him to forgive Nobukatsu. Realizing that further family division would weaken his position, Nobunaga showed political foresight: he not only spared his brother, but also granted amnesty to the elders who had participated in the rebellion. This was a wise move that allowed him, after such a resounding victory, to further reduce the number of enemies within the clan.
As a result of the Battle of Inogahara, Nobunaga proved his right to leadership. His authority increased dramatically, and the number of enemies within the family decreased. Moreover, some of those who had recently opposed him, such as Shibata Katsuie, subsequently became his loyal allies and generals.
See also
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The Rebellion of Fujiwara no Hirotsugu
Fujiwara no Hirotsugu was the son of Fujiwara no Umakai, one of the most important court officials of the Nara period. By 740, the Fujiwara clan had held the reins of government for several decades. However, in 735–737, Japan suffered a severe trial: the country was hit by a devastating smallpox epidemic. It coincided with a series of crop failures, and together, disease and famine claimed the lives of about 40% of the population of the Japanese islands. The consequences were particularly tragic for the aristocracy. The mortality rate among the court nobility exceeded that among the common people. All four Fujiwara brothers, who held the most important positions at court — Umakai, Maro, Mutimaro, and Fusasaki — died.
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The Second Siege of Gassan-Toda Castle (1564–1565)
Mori Motonari (1497–1571), head of the powerful Mori clan, was one of the most influential daimyo in the Chugoku region, located in western Honshu. During the turbulent and violent Sengoku Jidai period, he waged continuous wars in an effort to expand his domain and strengthen his clan's power.
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The Siege of Inabayama Castle
The two-week-long siege of Inabayama Castle marked the dramatic climax of Oda Nobunaga’s campaign to assert control over Mino Province and decisively crush the Saitō clan. It was during this operation that Toyotomi Hideyoshi, then known as Kinoshita Tōkichirō, first shone brightly in competition with Nobunaga—emerging as the future heir to Japan’s unification.
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The Siege of Wado Castle
In 1335, the Shiina clan built Uozu Castle as an auxiliary stronghold supporting Matsukura Castle. By 1570, it had fallen under the control of the Uesugi clan, rapidly emerging as a strategic fortress in Etchū Province. For many years, Kawada Nagataka served as its commander.
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The siege of the Ishimama Honganji monastery
In Japanese history, the siege of Ishiyama Hongan-ji — the main stronghold of the Ikkō-ikki movement during Oda Nobunaga’s campaign — is considered the longest, lasting from August 1570 to August 1580.
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The Battle of Norada
The Battle of Norada is a striking example of a clash during the Sengoku Jidai period, when numerical superiority did not always guarantee victory, even in open battle.
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Battles of Kawanakajima
The Battles of Kawanakajima were a series of fierce conflicts during Japan's Sengoku period, waged between Takeda Shingen of Kai Province and Uesugi Kenshin of Echigo Province from 1553 to 1564. These battles centered around the strategic Kawanakajima plain, lying between the Sai and Chikuma rivers in northern Shinano Province, now within Nagano City. The rivalry began when Shingen took control of Shinano, forcing Ogasawara Nagatoki and Murakami Yoshikiyo to seek refuge with Kenshin, prompting repeated clashes.
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Siege of Odawara 1590
The Third Siege of Odawara in 1590 was a pivotal moment in Toyotomi Hideyoshi's efforts to neutralize the Hojo clan as a challenge to his authority. In the months leading up to the siege, the Hojo made significant, hurried improvements to the castle's defenses as Hideyoshi’s intentions became clear. However, despite Hideyoshi's overwhelming force, there was little actual combat during the siege.
