You can't have a revolution without muscle, and nobody during the Bakumatsu had more muscle than Saigo Takamori. See how the big brother of the Meiji restoration helped take down the Shogunate!
Saigo and Hisamitsu were unable 
to come to an agreement,
Saigo y Hisamitsu nunca concordaban
Saigo e Hisamitsu não
concordavam em diversos assuntos