[2] It also set itself apart from the other branches due to its history of thwarted political ambition—the founder, Munetake, had hoped to become his father's heir but was passed over for Yoshimune's eldest son, Tokugawa Ieshige.

Further attempts were made by the family to place Sadanobu as the next shogunal heir, but they were thwarted by the political clique of Tanuma Okitsugu, who was then in power as the chief rōjū.

At the age of 17, he was adopted by Matsudaira Sadakuni, the daimyō of Shirakawa Domain in Mutsu Province, over the objections of the Tayasu clan, which was thus left without an heir.

[4] Sadanobu worked ceaselessly to fix the economic situation in Shirakawa, finally saving it and bringing its finances and agriculture back to stability.

This had been caused by a combination of poor weather, volcanic eruptions and the mercantilist policy implemented by Tanuma Okitsugu intended to commercialize agriculture and thus increase tax income.

The Kansei Reforms aimed fiscal consolidation through severe austerity policies and sumptuary laws, rural reconstruction, and preventing the recurrence of popular uprising.

In 1792 he was also faced with a diplomatic crisis, in which the Russian officer Adam Laxman landed in Ezo with a large force of men to return a Japanese castaway Daikokuya Kōdayū and to open trade negotiations.

However, while Sadanobu was making apparent progress in terms of national defense and foreign affairs, criticism over the harsh and largely unpopular policies of the Kansei Reforms were steadily gaining strength.

Although in his autobiography he states that "one should retire before discontent sets in",[7] in fact he was ordered to resign, receiving the notification while on a trip to investigate maritime defenses.

He also created the Nanko Park near Shirakawa Castle by building a reservoir with a vast garden which, most unusually for the time, he insisted be open to the common people, regardless of social status.

Officially, he desired to take over the former territory of the Hisamatsu-Matsudaira family because it had a seaport; however, it was clear that Shirakawa would be unable to withstand the financial deterioration caused by the Edo Bay security measures, and he wished to pass this responsibility on to Hotta Masaatsu of Sakura Domain, whom he disliked.

He quickly became the subject of a vicious slander campaign in which handbills of unknown provenance were distributed throughout Edo accusing him of ordering the slaughter of townsmen during the fire and of his fleeing the burning city in his loincloth to hide in Fukui Domain.

He started to show signs of recovery from his illness, enough to hold a poetry reading with his retainers and to discuss politics with his son Sadanaga on the afternoon of June 14, but died that same evening.