Did Sanada Yukimura propose his father’s “secret plan” at the siege of Osaka?

Nobushige’s proposal, said to be his father Masayuki’s last words, was not accepted

  The anecdote that Sanada Masayuki, who was confined in Kudoyama, had passed on a secret plan to his son Nobushige, envisioning a confrontation between the Tokugawa and Toyotomi, is it true? “Bushō Kanjō-ki” (also known as “Saigyoku-wa”) is a collection of episodes of warlords who were active from the Sengoku period to the early Edo period. It contains many unique stories and has also become a source for historical novels. 

  The book was written in 1716 (Shōtoku 6) by Kumazawa Tannan, a retainer of the Hirado domain in Hizen Province, and claimed to be a disciple of Kumazawa Banzan, a retainer of the Okayama domain in Bizen Province and also a Yomei-gaku scholar. However, there is no historical evidence for his background, making the credibility of the book remain in doubt.

  While the book introduces very interesting episodes, the fact that it lacks supporting historical sources detracts its historical value ((it is more of a collection of anecdotes than a historical document).

  Interestingly, a similar strategy is also mentioned in the “Sanada-ki”, (Chronicles of the Sanada Clan), where Masayuki expresses regret, saying, “If I had three more years to live, I could easily have taken control of the country and presented it to Hideyori (Toyotomi).”

  However, Masayuki’s strategy in the “Sanada-ki” specifies Kuwana (Kuwana City, Mie Prefecture) as the place to march, and the force is stated to be 3,000 instead of 20,000. The other parts of the story are almost the same.

  After telling the strategy to Nobushige, Masayuki suddenly feels unwell and dies dramatically immediately after drinking water, without saying that if Nobushige proposed the same strategy, the Toyotomi family’s senior retainers would probably reject it.

  Subsequently, Nobushige entered Osaka Castle and proposed the strategy as Masayuki’s last words, but it was not accepted in the end. The point is that if the proposal comes from Masayuki, who has rich practical experience in warfare, it would be accepted, but Nobushige’s lack of achievements finally caused its rejection.

  This story is a well-known anecdote, but can it be believed as a fact? Let’s think about it a little further.

  First of all, “Bushō Kanjō-ki” has poor historicality. The story sets up a tense situation where Masayuki is approaching death, making it very dramatic and stimulating. However, as mentioned above, it is difficult to believe that Masayuki was seriously considering “overthrowing Ieyasu” in his later years, as he was in a difficult situation due to illness and economic hardship. Therefore, it is considered unlikely to be a historical fact.

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