This came in the wake of the signing of the Harris Treaty on 1858/6/19, a deeply unpopular move among many prominent figures in the realm not only in terms of disagreements as to what the shogunate's foreign policy approaches or stances should be, but also because the treaty was signed without imperial approval. Further, many of those who opposed the signing of the treaty also actively supported Tokugawa Yoshinobu rather than Tokugawa Yoshitomi (Iemochi) as the shogunal successor, plotting behind the back of the shogunate to gather support among court nobles, daimyo, and others, as well as imperial orders explicitly backing Yoshinobu and calling for the negation of the treaty. Yoshitomi was officially named shogunal heir on 1858/6/25.
The purges began as early as 1858/7/5, with Tokugawa Nariaki (former lord of Mito han) being sentenced to house arrest, and Tokugawa Yoshikumi (lord of Nagoya han) and Matsudaira Yoshinaga (lord of Fukui han) being forced into retirement and house arrest. The shogunate designated Matsudaira Yoshichika (lord of Takasu han) to become the new lord of Nagoya, and Matsudaira Naokiyo (lord of Itoigawa han) to become the new lord of Fukui. Iesada died the following day, on 7/6. Formal visits to Edo castle by Tokugawa Yoshinobu (the rival claimant for the position of shogunal heir), as well as lord of Mito han Tokugawa Yoshiatsu, were briefly suspended.
Wakadoshiyori Hongô Yasukata, Sobashû Ishikô Masahira, and one of the shogun's court physicians, Oka Rekisen'in, were among many others also dismissed from their positions and placed under house arrest.
While the Purge helped Naosuke consolidate power in the hands of his supporters, it also contributed significantly to the anger of his opponents, leading eventually to his assassination in 1860 in the Sakuradamongai Incident.
- Marco Tinello, "The termination of the Ryukyuan embassies to Edo : an investigation of the bakumatsu period through the lens of a tripartite power relationship and its world," PhD thesis, Università Ca' Foscari Venezia (2014), 271n430, 273-274.
- Ishin Shiryô Kôyô 維新史料綱要, vol 2 (1937); vol 3.
- Ishin Shiryô Kôyô 維新史料綱要, vol 2 (1937), 597.
- Ishin Shiryô Kôyô 維新史料綱要, vol 3 (1937), 4, 5, 7.
- Ishin Shiryô Kôyô 維新史料綱要, vol 3 (1937), 6-7, 40.
- Ishin Shiryô Kôyô 維新史料綱要, vol 3 (1937), 7.