Er?? what revolution?

The tokugawa family became shoguns in 1604, four years after the battle of Seikigahara, and they ruled until 1868, when a young man called Meiji was choosen to become Japan's new emperor..

And between 1864 and 1868 there was a some wars, one of them called the boshin wars etc, Shinsengumi was choosed to protect the shogun in Kyoto, that was their purpose, but shinsengumi was founded in 1863, and ended in 1868. Right after the battle at Ikedaya all went down for shinsengumi, with the politics etc, the chooshu had began moving and in that time, the last days(more like years) of the edo-era (1604-1868) was called bakumatsu.

well buy/download a movie called "When the last sword is drawn" (don't know the japanese title) then you'll get alot of facts, and it's a great movie also.