Kazuhiro Marushima: Tokugawa Ieyasu and the Siege of Osaka

2025/07/16

The current international situation is far from stable. However, when considering "when and why it became unstable," the answer does not come easily. For people living in the same era, it is not easy to understand when the turning point was or what the cause was.

When I say I study the Sengoku period and Sengoku daimyo, I am often asked about the achievements of Oda Nobunaga and Toyotomi Hideyoshi. While those conversations are enjoyable, the true appeal of the Sengoku period lies in the ability to examine the transition from the medieval era, where resolution through violence was taken for granted, to the early modern era, which was more restrained in the use of violence.

However, one tends to draw an "orderly story." While academia is a logical endeavor, actual human movements are not. In the political science I studied at Hiyoshi, the most memorable theme was "Do humans always act rationally?"

Below, I would like to re-examine the Siege of Osaka, in which the Edo Shogunate destroyed Toyotomi Hideyori. In fact, Tokugawa Ieyasu did not intend to destroy Toyotomi Hideyori from the beginning. It seems he wanted Hideyori to leave Osaka Castle, disband the gathered ronin (masterless samurai), move to Yamato (Nara Prefecture), and settle down as a daimyo under the Edo Shogunate system. Yamato was a province once ruled by Hideyori's uncle, Toyotomi Hidenaga, and could be considered a place with deep ties to the Toyotomi family. It was not a bad deal.

However, Ieyasu's intentions did not reach Toyotomi Hideyori and his mother, Yodo-dono. The young Hideyori was dragged along by the radicals around him and expelled the moderates who were trying to arrange a peace treaty with the Shogunate. The expulsion of the person in charge of negotiations is, in modern terms, equivalent to closing an embassy. To Ieyasu's eyes, it appeared as a rejection of diplomacy, and Hideyori hurriedly made excuses. In other words, the Winter Campaign of the Siege of Osaka can be seen as having started in a way that even Ieyasu did not desire.

Therefore, peace negotiations continued even after the Winter Campaign. Just before the Summer Campaign, Hideyori and his mother decided to accept Ieyasu's demands. However, they could not implement the disbandment of the ronin, which was the core of the peace conditions. They could not suppress the pressure from the ronin. Judging that Hideyori lacked the capacity to act as a responsible party, Ieyasu broke off negotiations and destroyed the Toyotomi family in the Summer Campaign.

However, Hideyori's seppuku was not Ieyasu's order. It was an instruction from the second shogun, Tokugawa Hidetada. Ieyasu left the decision to his son and "fled."

What we can see from the process of the Siege of Osaka and the fall of Toyotomi Hideyori is the reality that nothing proceeded according to anyone's intentions. The attitude of seeking easy-to-understand answers is perhaps what should be avoided most.