Japan was in a state of internal political turmoil and external pressure from foreign powers in the mid-nineteenth century. For centuries the Shogun ruled and the Emperor was a figurehead. The political system was about to change.

The story of the Shinsengumi began in 1863 when most of their members joined a group known as the Roushitai which travelled to Kyoto, the capital, to lend their allegiance to the Shogunate. However, after the leader of the Roushitai revealed his true intent to have the Roushitai shun the Shogun and support the Emperor a group of men left.

After gaining the sponsorship of the Aizu domain, on August 18, 1863 the group adopted the name "Shinsengumi" (New Selection Group). The first chief of the Shinsengumi, Serizawa Kamo was killed by his own men. Now, under the leadership of Kondou Isami, a dojo owner and teacher of swordsmanship from Tama (rural Edo or present day Tokyo) and his friend Hijikata Toshizo his vice chief, the group reorganized and patrolled the city to eradicate anti-shogunate forces.

The Shinsengumi's most well known activity was the raid on Ikedaya Inn on June 5, 1864 where many revolutionaries who planned to overthrow the Shogun, burn the capital and abduct the Emperor were apprehended or killed.

The security force was threatened by internal factionalism in the Itou Affair of 1867 when a group of men left. They were later eliminated.

By 1868, the Shogunate engaged in open armed conflict with the Imperialist faction consisting of Satsuma, Choshu and Tosa domains. The Shinsengumi became part of the Shogun's army and fought at Toba and Fushimi (located outside of Kyoto), Nagarayema where Kondou Isami was arrested and beheaded, Aizu and finally Hakodate (Hokkaido Island) in 1869 where Hijikata Toshizo was killed.

Though of humble origin as masterless samurai, farmers, or merchants, they made a name for themselves equal to any warrior in Japanese history. Because they fought on the losing side of the Boshin War, they were then villified, but thanks to popular depictions, they are being rediscovered today.

Thus, to understand the significance of this small group of men it is necessary to appreciate fiction but study the complex history as carefully as possible.