Here You are!A Story of Tokugawa Ieyasu
If you are a Japanese, you must have your own view on Nobunaga, Hideyoshi, and Ieyasu; the three "Sengoku"-era heroes of Japan.
Till the early 1600's, whole Japan had been in a warring state among feudal samurai lords for 150 years, which is called "Sengoku-Jidai" in Japanese.
The three samurai heroes who put an end to this era were Oda Nobunaga, Toyotomi Hideyoshi, and Tokugawa Ieyasu. (Note that their name is expressed with their family name first.)
Nobunnaga was a kind of revolutionary samurai born in a house of a mediocre samurai lord; Hideyoshi was a very skillful and talented samurai born in a farmer's house; and Ieyasu was a very cautious but brave samurai born in a house of a minor samurai lord.
Nobunaga was standalone from his birth to death; Hideyoshi was a subordinate samurai-general till assassination of his lord Nobunaga; and Ieyasu was a junior partner of Nobunaga through alliance, though Ieyasu founded the Tokugawa shogunate that lasted for 260 years till 1868.
The three samurai heroes were, all alike, bloody through their careers. But, Ieyasu was more unique even than other samurai heroes in that he killed his wife and eldest son.
In 1579 when Ieyasu and his wife were in their late 30's and their eldest son was just 21 years old, Ieyasu killed his wife Sena-hime and his son Nobuyasu.
Nobuyasu married the eldest daughter of Oda Nobunaga to have two daughters. When Nobuyasu was forced to commit a suicide by his father Ieyasu and actually died, his wife Toku-hime left her infant daughters at Ieyasu, leaving however not for her powerful father Nobunaga but for her brother.
Yet, this incident did not affect the relationship between Oda Nobunaga and Tokugawa Ieyasu. In fact, it is said that Ieyasu had sent a veteran samurai of his house to Nobunaga to secure Nobunaga's consent, as the Nobunaga's daughter was the wife of the Ieyasu's son to be killed by Ieyasu. Nobunaga then living north of Kyoto or west of Tokugawa's dominion respected the extraordinary will of Ieyasu.
At the time, the alliance of Nobunaga and Ieyasu was standing face to face against a strong samurai clan called Takeda who maintained its vast territory mostly in the mountainous areas between Owari (Nagoya) and Musashi (Tokyo). In one time, the two allies together mobilized 38,000 samurai troops equipped with 3,000 matchlock guns against 15,000 samurai troops on the Takeda side including 1,500 or so experienced cavalry.
But, in a seaboard region in the south of the Takeda's territory, there had been a dominant samurai clan called Imagawa to whom Ieyasu had been forced to follow. Young Ieyasu had married a niece of the chief of the Imagawa clan. But, when the chief was killed by Oda Nobunaga in a miracle war and victory for Nobunaga in 1560, Ieyasu had left Imagawa and returned to his home region and castle called Okazaki-jyo, leaving his wife Sena-hime and his little son Nobuyasu in the territory of Imagawa. The Imagawa clan had got angry at Ieyasu, so that the parents of Sena-hime had been forced to commit a suicide. Nonetheless, two years after the tragedy, Ieyasu could take his wife and son to the Okazaki-jyo castle through an exchange of hostages. Several years after this incident, the Imagawa clan went to ruin due to invasion by the Tokugawa clan and the Takeda clan.
Then, as time went by, Tokugawa Ieyasu arranged a marriage of his son Nobuyasu with the eldest daughter of Oda Nobunaga. As further time went by, Ieyasu and his son Nobuyasu, joining Nobunaga, fought fierce battles against the Takeda clan. But, one day, Ieyasu decided to kill his wife and his son while the long war against the Takeda clan was still going on.
At the time Ieyasu lived in a castle called Hamamatsu-jyo on the front facing Takeda's forces, while having his son Nobuyasu live and manage Okazaki-jyo. But, in the Okazaki-jyo castle, Ieyasu also had his mother live with her remarried family. Accordingly, there were three women important for Ieyasu living together or partly separately in and around the Okazaki-jyo castle.
Ieyasu's mother hated the Imagawa clan, since she had been forced a divorce on from her husband, namely Ieyasu's father who died in 1549, due to a complicated relationship between her husband and the Imagawa clan. Ieyasu's daughter in law, or his son's wife, Toku-hime was the eldest daughter of the mighty senior lord Nobunaga who had actually helped Tokugawa destroy the Imagawa clan. But, Ieyasu's wife was a niece of the deceased head of the Imgawa clan whom Nobunaga had killed in a miracle war in 1560 when Nobunaga was so minor and Imagawa was so mighty.
So, in 1579 there were three women important for Ieyasu living together or partly separately in and around the Okazaki-jyo castle. But, only Ieyasu's wife was from the Imagawa clan, a kind of enemy for Ieyasu's mother and his daughter-in-law's father Nobunaga. And, Imagawa had been rather closer to Takeda traditionally and regionally as Takeda's domain was north of Mt. Fuji and Imagawa's east of the holy mountain.
This is a dangerous situation. Something must happen. And, to everybody's surprise, Ieyasu sent assassins, namely some samurais from the Hamamatsu-jyo castle, to kill his wife Sena-hime, while sending his confidential samurais to his son Nobuyasu who was then brought to a branch castle near Takeda's territory where they forced him to commit a suicide.
After this incident, Nobuyasu's wife Toku-hime left her infant daughters at Ieyasu, leaving however not for her powerful father Nobunaga but for her brother. Finally only Ieyasu's mother survived in the Okazaki-jyo castle.
Long after this incident in 1579, Tokugawa Ieyasu did not have the legal wife. His second legal wife was a sister-in-law of Toyotomi Hideyoshi who strategically arranged this strategic marriage in 1586, since at the time Hideyoshi, as the sole successor of Oda Nobunaga, conquered so many regions in Japan to be regarded as the promised ruler of whole Japan which he became a few years later.
However, after the death of Toyotomi Hideyoshi in 1598, Tokugawa Ieyasu survived fairly and eventually destroyed the Toyotomi clan.
In this way, the Tokugawa clan and the house of Tokugawa shugunate governed Japan till 1868 when a great civil war resulted in the Meiji Restoration of the Imperial authority and the start of modernization of Japan.
Finally, why did Ieyasu have to kill determinedly his wife Seri-hime and his eldest son Nobuyasu? It is one of mysteries in the Japanese history.
But, there were three women important for Yeasu, namely, his mother, his wife, and his son's wife who was the eldest daughter of powerful Nobunaga. And, 20 years before, his wife had enjoyed the highest state and the richest life among the three, since her mother was a sister of the then chief of the Imagawa clan.
And after this tragic and mysterious incident, only Ieyasu's mother remained in the main castle of the Tokugawa clan.
So, my theory is that Ieyasu's mother gave a warning to Ieyasu that his wife devised a secret plan to have her son Nobuyasu kill Ieyasu and revolt against Nobunaga to tie up with the Takeda clan. Seri-hime was secretly trying to restore Imagawa. Unless Ieyasu had taken a decisive action, he would be killed by his wife and son sooner or later. It must have been a fatal advice from his mother to Ieyasu.
Of course, there are many other theories. One of them is that Tokuhime, the wife of Nobuyasu, wrote a letter to her powerful father Nobunaga asking to punish her husband and his mother, since Nobuyasu betrayed her with help from his mother. Accordingly, Nobunaga demanded death of his wife and son to Ieyasu, which Ieyasu executed faithfully, though even without an apparent grudge to his senior partner of war Nobunaga.
Now, a public holiday of Japan, the Sports Day, is going to close, since the Tokyo Olympic Games were started on October 10, 1964, an age and more ago.
(In addition, two infant daughters of Nobuyasu and Toku-hime who had terrible grandfathers Nobunaga and Ieyasu grew up peacefully and lived long in happiness in the era governed by the Tokugawa clan...)