The Americans showing up probably refers to the 1854 Treaty of Kanagawa https://en.wikipedia.org/wiki/Convention_of_Kanagawa https://en.wikipedia.org/wiki/Conve

The Americans showing up probably refers to the 1854 Treaty of Kanagawa https://en.wikipedia.org/wiki/Convention_of_Kanagawa https://en.wikipedia.org/wiki/Convention_of_Kanagawa which forced the opening of Japanese ports to American ships. The most recent battles in Japan prior to that that I'm aware of are the rebellions that broke out in 1837 due to famine: https://en.wikipedia.org/wiki/Tenp%C5%8D#Rebellion https://en.wikipedia.org/wiki/Tenp%C5%8D#Rebellion