Second Chōshū Expedition

In the summer of 1866 (Keiō 2), Japanese history reached a major turning point. The "Second Chōshū Expedition," in which the Tokugawa shogunate attempted to mobilize over thirty domains nationwide to suppress Chōshū, ended in complete military defeat and became the decisive turning point toward the Meiji Restoration the following year.

The First Expedition and the Formation of the Satchō Alliance

In the Kinmon Incident (also called the Hamaguri Gate Incident) of 1864 (Genji 1), the Chōshū domain was branded a "rebel against the court" for directing its forces against the imperial court. In the First Chōshū Expedition of that same year, Chōshū submitted under pressure from other domains, and a temporary settlement was reached. However, within the Chōshū domain, the Radical Faction (anti-shogunate hardliners) regained power, overthrew the Military Preparedness Submission Faction (conservatives) who had led the first expedition, and seized control—resulting in civil conflict within Chōshū domain.

Threatened by this situation, the shogunate again planned to suppress Chōshū. But this time circumstances were entirely different. In January 1866 (Keiō 2), Satsuma and Chōshū domains concluded the "Satchō Alliance" through the mediation of Sakamoto Ryōma and Nakaoka Shintarō. Satsuma pledged not to support the shogunate's expedition against Chōshū and further supplied weapons (including Minié rifles). This sealed the isolation of the shogunate.

Takasugi Shinsaku and the Kiheitai—The Birth of Modern Armies Beyond Status

The core of Chōshū's military strength was the various units organized by Takasugi Shinsaku (1839–1867), particularly the "kiheitai" (extraordinary militia). Founded by Takasugi in 1863 (Bunkyū 3), the kiheitai overturned the traditional military system restricted to samurai status and recruited talented individuals regardless of birth—peasants, merchants, and rōnin alike. This represented a watershed in Japanese military history and became the precursor to the universal conscription system (conscription edicts) that would define the Meiji period.

The kiheitai was not merely a mixed force but a prototype of modern military organization, emphasizing discipline and practical training. Equipped with Western-style rifles (Minié and Enfield rifles), its soldiers mastered not only traditional Japanese sword and spear combat but also bayonet fighting and artillery. Takasugi Shinsaku's revolutionary military reforms gave Chōshū a qualitative superiority in manpower against shogunate forces.

Four-Front Campaign—The Complete Collapse of Shogunate Forces

On June 7, 1866 (Keiō 2), shogunate forces attacked Chōshū from four directions.

At the Ōshima sector (attack on Ōshima in the Seto Inland Sea), the shogunate fleet bombarded and occupied the island. But the kiheitai under Takasugi Shinsaku's direct command launched a night assault, boarding the enemy vessels, with Takasugi himself fighting fiercely aboard an enemy ship. The shogunate forces were compelled to withdraw from Ōshima.

At the Geishū sector (present-day Hiroshima area), as shogunate forces attempted to advance across the Saiki and Ose rivers, Chōshū's rifle units exploited the terrain and repulsed them.

At the Iwami sector (present-day Shimane area), the shogunate's attack on Masuda was outflanked by Chōshū's seizure of the strategic Hamada Castle, and the shogunate's Iwami magistracy was occupied.

The fiercest fighting occurred at the Kokura front (near present-day Moji, Kitakyūshū). The Kokura domain (shogunate-aligned) clashed with Chōshū, and while the Kokura side initially held the advantage, Chōshū launched a major counteroffensive from August onward. Kokura Castle was abandoned and burned (August 1), and the withdrawal of shogunate forces continued.

The Death of Shōgun Iemochi and the Settlement of the Campaign

As the shogunate faced hardship on all four fronts, a decisive blow struck on July 20: Shōgun Tokugawa Iemochi, who had been directing operations at Osaka Castle, died suddenly of acute cardiac beriberi. He was twenty-one years old.

The shōgun's death robbed the war of its justification for continuation. His successor, Tokugawa Yoshinobu, announced a ceasefire in September. But the military arithmetic was unmistakable—the shogunate had suffered complete defeat at the hands of Chōshū alone.

The Japanese Sword and the Kiheitai—Between Bushidō and Modernity

The Second Chōshū Expedition marks a turning point in the history of Japanese sword culture. Through the kiheitai's battles, the Japanese sword shifted from being the primary weapon to becoming a supplementary weapon to modern rifles. The kiheitai's principal armament was Western-style rifles; while the Japanese sword and bayonet saw use in close combat, the decisive force was gunfire.

Yet at the same time, the leaders of the kiheitai—Takasugi Shinsaku, Yamagata Aritomo, and Katsura Kogoro—were all accomplished swordsmen. The sword that Takasugi Shinsaku favored (some accounts hold it to be a blade of Satsuma tradition) served as the spiritual foundation of his revolutionary actions. Yamagata Aritomo had undergone rigorous training in sword arts and would later become central to the Meiji army.

The swords worn at the hips of the kiheitai's warriors were undergoing a transformation in meaning—from "the soul of the samurai" to a symbol of "the fighting spirit of ordinary people." This also represented a cultural preparation period leading toward the Meiji prohibition on sword-wearing (Haitōrei, 1876).

The Chain Toward the Restoration of Imperial Rule

The failure of the Second Chōshū Expedition symbolized the end of the shogunate's governing capacity. After defeat, the new shōgun, Tokugawa Yoshinobu, attempted political reforms, but he could not alter the tide of the times. On October 14, 1867 (Keiō 3), Yoshinobu submitted a petition for the Return of Power to the Emperor (Taisei Restoration), and through the Edict of Restoration of Imperial Rule on December 9, the Tokugawa shogunate came to its true end.

The Satchō Alliance mediated by Sakamoto Ryōma—the Second Chōshū Expedition exists within the chain of events it set in motion. As the last large-scale military engagement of an era when the blades of the final years of the shogunate expressed final political will, the Second Chōshū Expedition stands as a historical event positioned between the Japanese sword and modernity.