The Battle of Nagaragawa

Saito Toshimasa, later known as Saito Dosan, is considered one of the typical Sengoku daimyo—minor samurai who, in the 16th century, managed to achieve the status of independent princes by the harshest and sometimes unsavory means. His ruthlessness towards his rivals earned him the nickname “Mino no Mamushi” — “the viper of Mino.”

First steps

At first, Toshimasa served the governors of Mino Province, the Toki clan. In 1526, he took Miyoshi, the former wife of Mino Province daimyo Toki Yoshiori (Yoriaki), as his concubine.

In 1527, Miyoshi gave birth to a son, later known as Saito (Toki) Yoshitatsu. Since the child was born less than nine months after the beginning of the union between Toshimasa and Miyoshi, many researchers assume that Toshimasa was not his father and refer to Yoshitatsu as an adopted son.

Rise to power

In 1542, Toshimasa forced the old daimyo of Mino Province, Toki Yoshiori, into exile and became the sole ruler of the land.

In 1548, he strengthened ties with the neighboring Oda clan by marrying his daughter to Oda Nobuhide's son, Oda Nobunaga.

Resignation and monasticism

In 1554, Toshimasa reached the age of sixty and decided to retire. He shaved his head and took the monastic name Dosan, under which he went down in history. He appointed the eldest of his three sons, Saito Yoshitatsu, as head of the clan.

However, this decision was made under pressure from his closest associates. Dosan himself did not particularly like his eldest son and preferred his middle son, Mogoshiro (Sonshiro). After his retirement, Dosan soon began to sharply criticize Yoshitatsu's actions and openly emphasize Mogoshiro's virtues. This exacerbated the relationship between father and son, and eventually Yoshitatsu decided to conspire.

The Inabayama Conspiracy

In October 1555, Yoshitatsu retired to Inabayama Castle and spread rumors that he was seriously ill. In fact, he did suffer from leprosy, but despite his illness, he remained quite alert and active.

At his request, his uncle, Nagai Michitoshi, invited his younger brothers, Mogoshiro and Kihēji, to the castle, ostensibly to visit the sick man. However, upon arriving there in November 1555, both brothers were killed on Yoshitatsu's orders.

Upon learning of the death of his two sons, Dosan flew into a rage and burned down the settlements around Yoshitatsu's castle. It became clear that armed conflict was now inevitable.

Preparing for battle

Yoshitatsu sought support from the former daimyo Toki Yoshiori, while Doson turned to his son-in-law, Oda Nobunaga, promising to give him the province of Mino in the event of victory. However, Yoshitatsu had an advantage: many residents of the province remained supporters of the exiled Yoshiyori, and a significant part of the troops went over to his side.

With the support of the elders, Yoshitatsu managed to assemble a huge army of about 17,500 soldiers, while Dosan was only able to field 2,700 fighters (according to other sources, about 2,500).

The Battle of the Nagara River

In the spring of 1556, the armies of Dosan and Yoshitatsu set up camp on opposite sides of the Nagara River. On the morning of April 20, at the “hour of the dragon,” Yoshitatsu's army was the first to launch an attack.

In response, Dosan's army descended from Mount Tsuruga to the Nagara River. Yoshitatsu's vanguard, led by Takekoshi Dojin, was the first to enter the battle: it crossed the river and broke through to Dosan's headquarters. However, Dosan's troops managed to regroup and hold their positions.

Yoshitatsu himself then led a large detachment that crossed the river and engaged in fierce combat with Dosan's army. According to one version, a pontoon bridge made of boats and rafts was built for the crossing.

In the heat of battle, Nagai Tadasaemon and a group of warriors attempted to capture Dosan alive. But another detachment of Yoshitatsu, commanded by Komaki Genta, captured Dosan's headquarters with a swift strike and cut off his head, finally deciding the outcome of the battle in Yoshitatsu's favor.

Consequences

After receiving Dosan's request for help, Oda Nobunaga advanced to the battlefield, but was too late. After crossing the Kiso River, he stopped at Oura Fort, where he learned of his father-in-law's death. Yoshitatsu sent a detachment against Nobunaga, and after a series of minor skirmishes, Nobunaga was forced to retreat to Kiyosu Castle. Thus, Yoshitatsu became the sole ruler of Mino Province.

Yoshitatsu's reign

According to some sources, such as the chronicle of Ota Gyūichi, Yoshitatsu did not feel joy after his father's death. Moreover, there were rumors that he abandoned all administrative affairs for a while and even began to call himself Hankā, after a famous patricide from the past.

However, Yoshitatsu soon returned to his duties as head of the clan and proved himself to be a fairly wise and prudent ruler. Under his leadership, the Saito clan's position was significantly strengthened.