Matsudaira Katamori, the last daimyō of the Aizu Domain
By 1867, it was clear that the shogunate could no longer hold out against the pro-imperial forces led by the Satsuma and Chōshū domains. The shōgun Tokugawa Yoshinobu was willing to relinquish a measure of his authority only on condition that the shogunate retained political primacy. In November 1867, he nevertheless agreed to accept a compromise proposed by the Tosa Domain (土佐藩), according to which he would return political authority to the emperor and head a council of daimyō. By that time, however, Satsuma and Chōshū had decided to overthrow the shogunate by force. On January 3, 1868, their troops seized the imperial palace in Kyōto and proclaimed an imperial restoration (王政復古 ōsei fukko).
Yoshinobu withdrew to Ōsaka Castle, but some of his vassals were unwilling to submit. Shogunate troops from the castle engaged in a pitched battle with imperial forces at Toba and Fushimi, just south of Kyōto. The better-organised imperial forces, although outnumbered, trounced to shogunal forces, and Yoshinobu quietly set sail for Edo. Imperial forces under the command of Prince Arisugawa Taruhito (有栖川宮熾仁親王 Arisugawa-no-Miya Taruhito-Shinnō, 1835–1895) then advanced toward Edo. Still, under an agreement reached between Saigō Takamori of Satsuma and Katsu Kaishū, a Tokugawa retainer, the city surrendered without resistance.
Chōshū troops from various units (Univ. of Tokyo Library)
Aizu troops disembarking in Fushimi
The Boshin War has been described either as a conflict between the bourgeoisie and an absolute shogunate, as a conflict between two absolute powers (the shogunate and the forces that would later establish the Meiji government), or as a struggle between absolutism and the forces striving to share power between the emperor, the shōgun, and the daimyō.