Mito Rebellion Part 4: Implications

Many conflicts broke out following the signing of treaties with foreign nations, eventually culminating with the civil war of Boshin, so what made the Mito rebellion especially significant? 

Well first of all, I must say that even if Japan was used to uprisings as the Edo period had plenty of them, they had mostly originated from the lower classes who struggled more during famines, diseases and disasters than the bushi (warrior) caste. 

It was different this time because Mito was not only a Shinpan domain, it was one of the gosanke, the three branch families of the Tokugawa clan which were eligible to be chosen as shōgun. The other two were Owari (Nagoya) and Kii (Wakayama) and all three descended from Tokugawa Ieyasu's younger sons.

The Bakufu had started losing ground following the assassination of Ii Naosuke (which was also the deed of young Mito samurai), but when Mito should have been a pillar, some of its political leaders were in fact involved in policies that went against decisions Edo had to take, and the armed conflict to resulted in was quite humiliating. The shogunate's armies were clearly not prepared nor trained enough.

This had dire consequences for the Bakufu as it further showed their inability to deal efficiently with an insurrection. Combined with the Anglo-Satsuma War as well as the Shimonoseki incident a year prior, internal conflicts and conflicts between domains and western powers contributed to crack what remained of the political stability. 

The Bakufu would remedy to that by having a naval mission from the UK and military mission from France come train their troops, but by the time the decision was made (1866), the damages were mostly irreversible. 

More: Conrad Totman, The Collapse of the Tokugawa Bakufu (1980)