First Chōshū Expedition

From the 7th to the 11th month of Genji 1 (August to December 1864), the Edo shogunate launched a massive military expedition against Chōshū domain. Known as the First Chōshū Expedition (or the Genji Expedition), it mobilized 36 domains and approximately 150,000 troops — the shogunate's final grand display of military authority in the bakumatsu era. Yet not a single battle was fought; through Saigō Takamori's skillful mediation, the campaign concluded bloodlessly.

The Kinmon Incident and the Background of the Expedition

The immediate trigger for the expedition was the Kinmon Incident (also known as the Hamaguri Gate Incident), which erupted on the 19th day of the 7th month of Genji 1 (August 20, 1864). The radical faction of Chōshū domain, driven from Kyoto in the political upheaval of Bunkyū 3 (the August 18 Coup, 1863), sought to settle accounts. Chōshū forces, led by Kusaka Genzui and Kijima Matabee, entered Kyoto and opened fire on the Hamaguri Gate of the imperial palace, defended by Satsuma and Aizu forces. The bombardment of the palace was high treason against the court; Chōshū troops were repulsed by the combined Aizu-Satsuma-Kuwana forces. Both Kusaka Genzui and Kijima Matabee fell in battle, and Chōshū's reputation was utterly shattered.

Two days after the Kinmon Incident, the court formally declared Chōshū a "rebel against the throne" (chōteki). The shogunate seized this opportunity, appointing Shōgun Tokugawa Iemochi as supreme commander (sōtoku) of the expedition and ordering the domains to participate. The expedition reportedly involved 36 domains and approximately 150,000 troops — an unprecedented mobilization throughout the Edo period and a symbol of the shogunate's authority over the han.

The Four-Power Bombardment of Shimonoseki in Coordination with the Expedition

As the First Chōshū Expedition progressed, the combined fleets of Britain, France, the Netherlands, and the United States bombarded Shimonoseki in the 8th month of Genji 1 (August 1864), in retaliation for Chōshū's earlier bombardment of foreign vessels (the Shimonoseki War, Bunkyū 3, the enforcement of the expulsion of foreigners). The "Four-Power Fleet Bombardment of Shimonoseki Incident" (the Bakan War) destroyed all of Chōshū's gun emplacements, forcing the domain to pay an indemnity of three million dollars (later borne by the shogunate). Caught between external and internal military pressure, Chōshū was gravely weakened militarily.

Saigō Takamori's Mediation and the Bloodless Conclusion

As the shogunate's expedition forces approached Chōshū, Saigō Takamori, participating as an expedition staff officer for Satsuma, focused his attention on the submission faction (conservative faction, the "common-sense faction") within Chōshū domain. Within the domain, following the defeat of the Kinmon Incident, a reaction against the radical faction (the Seigisha) took hold, and the submission faction (the "common-sense faction" led by Mukurnashi Tōta) gained the upper hand. Saigō pursued a resolution whereby Chōshū would submit and apologize, making an actual military campaign unnecessary.

Following negotiations, Chōshū accepted the shogunate's demands: (1) the execution of three senior retainers (karō) held responsible for the Kinmon Incident — Kokuji Shinano, Masuda Uemon no Suke, and Fukuhara Echigo; (2) the execution of four commanders (Shishido Samanosuke, Takenouchi Shohei, Nakamura Kurō, and Sakuma Sahei); (3) the transfer of the five loyalist court nobles (gokyo) in Yamaguchi to other domains. In the 11th month of Genji 1 (December 1864), Chōshū declared its submission to the shogunate, and the expedition forces withdrew.

However, this bloodless conclusion did not genuinely subjugate the radical faction of Chōshū domain. The remnants of the radical faction (Seigisha), who had been purged and suppressed by the submission faction, struck back when Takasugi Shinsaku led the kiheitai in the Kōzanji Uprising in the 1st month of Genji 2 (January 1865), and by spring they had regained control of Chōshū's government. Thereafter, Chōshū concluded an alliance with Satsuma domain (the Satchō Alliance, 1866) and openly mounted military resistance against the shogunate's Second Chōshū Expedition (1866).

The Impact on Sword Culture and the Military Transformation of the Bakumatsu Era

The First Chōshū Expedition was also a symbolic event marking a historical turning point: the coexistence of swords and modern weapons in the bakumatsu period. Warriors from the participating domains still wore the daisho (long and short swords) when they entered the field, but matchlock firearms (tanegashima) were being rapidly supplanted by Western-style guns (Minié rifles, Gever muskets) as the primary weapons, and the samurai's "sword" was increasingly becoming a symbolic and ceremonial implement. The fact that Chōshū domain's kiheitai recruited soldiers from commoners and farmers and adopted Western-style training and firearms demonstrated that the military system centered on the samurai and the sword was crumbling.

The massive mobilization displayed by the shogunate forces during the expedition paradoxically accelerated the substantive hollowing-out of the shogunate's authority. The "bloodless conclusion" through Saigō Takamori's mediation made clear to the domains' eyes that the shogunate had not militarily subjugated Chōshū but had merely settled the matter through political compromise. This perception — that "the shogunate is militarily unreliable" — spread among the domains, including Satsuma, and prepared the ground for the bakumatsu upheavals that would follow: the Satchō Alliance, the Second Chōshū Expedition, the Return of Political Power (taisei hōkan), and the Boshin War.

The First Chōshū Expedition is remembered in Japanese history as "an expedition of massive mobilization but not a single battle." Yet this very bloodless anticlimax symbolized the collapse of the shogunate's authority and became one of the pivotal turning points that determined the transition from the age of sword-bearing samurai to a modern military nation-state.