Satsuma Domain in the context of "Battle of Toba–Fushimi"

The Boshin War (戊辰戦争, Boshin Sensō), sometimes known as the Japanese Revolution or Japanese Civil War, was a civil war in Japan fought from 1868 to 1869 between forces of the ruling Tokugawa shogunate and a coalition seeking to seize political power in the name of the Imperial Court.

The war stemmed from dissatisfaction among many nobles and young samurai with the shogunate's handling of foreigners following the opening of Japan during the prior decade. Increasing Western influence in the economy led to a decline similar to that of other Asian countries at the time. An alliance of western samurai, particularly the domains of Chōshū, Satsuma, and Tosa, and court officials secured control of the Imperial Court and influenced the young Emperor Meiji. Tokugawa Yoshinobu, the sitting shōgun, realizing the futility of his situation, abdicated and handed over political power to the emperor. Yoshinobu had hoped that by doing this the House of Tokugawa could be preserved and participate in the future government.

The Shimazu clan (島津氏, Shimazu-shi; Japanese pronunciation: [ɕiꜜ.ma.(d)zɯ, ɕi.ma.(d)zɯꜜ.ɕi]) were the daimyō of the Satsuma han, which spread over Satsuma, Ōsumi and Hyūga provinces in Japan.

The Shimazu were identified as one of the tozama or outsider daimyō families in contrast with the fudai or insider clans which were hereditary vassals or allies of the Tokugawa clan.

The Government of Meiji Japan (明治政府, Meiji seifu) was the government that was formed by politicians of the Satsuma Domain and Chōshū Domain in the 1860s. The Meiji government was the early government of the Empire of Japan.

Politicians of the Meiji government were known as the Meiji oligarchy, who overthrew the Tokugawa shogunate.

Shishi (志士), sometimes known as Ishin Shishi (維新志士), were a group of Japanese political activists of the late Edo period. While it is usually applied to the anti-shogunate, pro-sonnō jōi (尊皇攘夷; lit. 'Revere the Emperor, Expel the Barbarian[s]') samurai primarily from the southwestern clans of Satsuma, Chōshū, and Tosa, the term shishi is also used by some with reference to supporters of the shogunate, such as the Shinsengumi.

There were many different varieties of shishi. Some, such as the assassins Kawakami Gensai, Nakamura Hanjirō, Okada Izō, and Tanaka Shinbei, opted for a more violent approach in asserting their views. Kawakami Gensai, in particular, is recalled as the assassin of Sakuma Shōzan, a renowned pro-Western thinker of the time. Several assaults on westerners in Japan have been attributed to the shishi and associated rōnin warriors. In a 2013 article, these assassins have been called "early terrorists" (German: frühe Terroristen) since they opted to spread terror among the foreigners. Other more radical shishi, such as Miyabe Teizō, plotted large-scale attacks with little regard for public safety. Miyabe himself was one of the ringleaders of the plot, foiled by the Shinsengumi at the Ikedaya Incident, to burn Kyoto at the height of the Gion Festival.

The Chōshū Domain (長州藩, Chōshū-han), also known as the Hagi Domain (萩藩, Hagi-han), was a domain (han) of the Tokugawa Shogunate of Japan during the Edo period from 1600 to 1871.

The Chōshū Domain was based at Hagi Castle in Nagato Province, in the modern city of Hagi, located in the Chūgoku region of the island of Honshu. The Chōshū Domain was ruled for its existence by the tozama daimyō of the Mōri, whose branches also ruled the neighboring Chōfu and Kiyosue domains and was assessed under the Kokudaka system with peak value of 369,000 koku. The Chōshū Domain was the most prominent anti-Tokugawa domain and formed the Satchō Alliance with the rival Satsuma Domain during the Meiji Restoration, becoming instrumental in the establishment of the Empire of Japan and the Meiji oligarchy. The Chōshū Domain was dissolved in the abolition of the han system in 1871 by the Meiji government and its territory was absorbed into Yamaguchi Prefecture.

Mutsuhito (睦仁; 3 November 1852 – 29 July 1912), posthumously honored as Emperor Meiji (明治天皇, Meiji Tennō), was the 122nd emperor of Japan according to the traditional order of succession, reigning from 1867 until his death in 1912. His reign is associated with the Meiji Restoration of 1868, which ended the Tokugawa shogunate and began rapid changes that transformed Japan from an isolationist, feudal state to an industrialized world power. Emperor Meiji was the first monarch of the Empire of Japan, and presided over the Meiji era.

At the time of Mutsuhito's birth, Japan was a feudal and pre-industrial country dominated by the isolationist Tokugawa shogunate and the daimyō subject to it, who ruled over Japan's 270 decentralized domains. The opening of Japan to the West from 1854 fueled domestic demands for modernization, and when Mutsuhito became emperor after the death of his father Emperor Kōmei in 1867, it triggered the Boshin War, in which samurai (mostly from the Chōshū and Satsuma Domains) defeated the shogunate and restored power in his name. Documents issued during his reign include the Charter Oath of 1868, Meiji Constitution of 1889, Imperial Rescript to Soldiers and Sailors of 1882, and Imperial Rescript on Education of 1890, in which he was advised by a group of oligarchs known as the genrō. Other major events which occurred during his reign include the establishment of the Cabinet in 1885, Privy Council in 1888, Imperial Diet in 1890, and military victories over China in the First Sino-Japanese War and over Russia in the Russo-Japanese War. Taiwan and Korea were annexed in 1895 and 1910, respectively. Emperor Meiji died in 1912, and was succeeded by his eldest son, Yoshihito.

The Satsuma–Chōshū Alliance (薩摩長州同盟, Satsuma Chōshū dōmei), or Satchō Alliance (薩長同盟, Satchō dōmei) was a powerful military alliance between the southwestern feudal domains of Satsuma and Chōshū formed in 1866 to combine their efforts to restore Imperial rule and overthrow the Tokugawa shogunate of Japan.