Satsuma and Chōshū had fought on opposing sides in Kyoto in 1864. During 1865, intermediaries worked toward cooperation as the shogunate prepared to punish Chōshū again. Komatsu Tatewaki and Saigō Takamori represented Satsuma in the discussions with Kido Takayoshi.
Ryōma entered the network of shogunal naval official Katsu Kaishū around 1862. Katsu advocated learning foreign techniques so that Japan could build maritime strength. He could connect that argument to ships and training projects, offering work as well as ideas to a fugitive who lacked an office of his own.
Two accounts give their first meeting different meanings. Katsu's later recollections say Ryōma came intending to kill him and became his disciple. Former Fukui lord Matsudaira Shungaku's account describes providing a letter of introduction, which permits a less hostile explanation. Their subsequent association is firmer ground than the exact intentions and dialogue of the celebrated conversion scene.
Katsu held office and connections; Ryōma needed protection and useful employment. Naval projects brought him into practical cooperation with men beyond one domain. Katsu, in turn, gained capable recruits with local knowledge and political contacts. Learning foreign navigation could serve a concern with Japan's defense without requiring approval of foreign coercion. The relationship changed what Ryōma could do through participation over time.
Discipleship gave Ryōma access to sustained naval work, while tying his opportunity to Katsu's standing in the shogunate. Katsu retained his own policy and would later negotiate Edo's surrender. Ryōma used the contacts for more mobile organizations and mediation. Their collaboration opened possibilities without requiring identical careers.
Kido’s surviving letter sets out six contingent undertakings. If war began, Satsuma would strengthen its forces in Kyoto and Osaka. It would advocate for Chōshū at court whether the domain gained the advantage, faced danger or the shogunal army withdrew. If Hitotsubashi, Aizu and Kuwana obstructed that advocacy, the agreement contemplated decisive fighting. The final clause promised cooperation in imperial service after Chōshū’s name was cleared.
Kido sent the record to Ryōma on the twenty-third day of the first month of the Japanese calendar in 1866. Ryōma’s red endorsement, dated the fifth day of the second month, confirmed that it matched their discussion. Satsuma subsequently refused participation in the second expedition.
Historical interpretation · Cooperation in a crisis or a plan for overthrow?
Read backward from the Restoration, the Satsuma–Chōshū agreement can look like an already complete alliance to overthrow the shogunate. Its surviving clauses are more conditional: reinforcement and court advocacy respond to specified outcomes in the Chōshū crisis, and fighting is contemplated if named opponents obstruct that advocacy. Cooperation in imperial service follows the clearing of Chōshū’s name.
Takahashi Hidenao’s 2005 study gives the pledge a broader military reading: Satsuma accepted Chōshū’s refusal of punishment and committed to decisive fighting against the Tokugawa forces if war followed. In his reconstruction the relationship already had a military character before the six articles were recorded.
A conditional agreement need not be merely diplomatic. The disagreement concerns how far its military commitment reached and what its participants already intended; the overthrow that followed cannot alone settle that question.
From 1863 Katsu developed naval training at Kobe, near Osaka and the Inland Sea. Ryōma joined his associated private school and worked among recruits from different domains. The official naval establishment opened in 1864. Its institutional backing and facilities were distinct from the private school, even though the two belonged to the same reform project.
Kobe's position near Osaka and the Inland Sea connected training to maritime routes and the political centers of the region. Learning to navigate and operate ships required shared discipline as well as technical instruction. Cooperation among mobile warriors could therefore become an institutional experiment in who was eligible to serve.
Recruitment beyond one domain allowed mobile warriors to enter technical work under shogunal sponsorship. Their political contacts also made the schools vulnerable. Students' involvement on the Chōshū side in the 1864 Kyoto crisis raised suspicion of a project protected by Katsu. Chōshū was a powerful domain in western Honshū opposed to shogunal policing in the capital.
Katsu lost office in 1864, and protection for his private recruits weakened. The official establishment closed in 1865, not at the same moment as his dismissal. Knowledge and contacts survived those changes. Ryōma and associates sought new sponsors, including Satsuma, a domain in southern Kyushu, and moved toward Nagasaki's commercial networks.
Around 1865 Ryōma and associates organized the Kameyama Shachū in Nagasaki under Satsuma protection. Shachū meant an association; this group combined maritime activity with procurement and political communication. Nagasaki already contained the merchants, interpreters and trading connections through which domains obtained foreign goods. The new organization assembled particular relationships within that established port economy.
Satsuma sponsorship gave men with weak independent legal standing resources and protection. It made their work possible while tying the association to a domain's purposes.
Members needed income, and ships needed financing. Political mediation became effective when it could move arms or cargo and establish credit. The Shachū connected those practical tasks to cooperation between domains. Its small size meant that outside merchants and sponsors supplied resources it could not own outright. A vessel used by the group might be chartered or supplied by a partner rather than purchased from its own capital.
The popular description of the Shachū as Japan's first company applies a later corporate label to an association dependent on patrons and partners. Its members performed shipping and brokerage, but those activities alone do not establish the legal form of a modern joint-stock company. Their contribution lay in making cooperation work through repeated transactions.
Sakamoto Ryōma mattered as a broker among armed domains, commercial and naval projects and proposals for political reorganization. His effectiveness came from borrowed authority and movement between Katsu Kaishū, Satsuma, Chōshū, Tosa and Nagasaki ventures rather than from a national office of his own.
Brokerage had limits: other leaders made final alliance and policy decisions, commercial claims could be contested, and Ryōma died before the new government was formed. Early biography expanded his part in national transformation. The documented achievement is narrower but substantial—connecting people and projects that formal institutions kept apart.
In 1861 Ryōma joined the Tosa Loyalist Party organized by Takechi Zuizan, also known as Takechi Hanpeita. Its members sought a stronger role for imperial authority amid the crisis over foreign relations. The movement operated within Tosa's politics; it was not simply an early version of Ryōma's later naval network.
In 1862 he left Tosa without permission. Dappan, unauthorized departure from a domain, broke the service relationship under which a samurai held status and protection. Outside it, he could encounter activists and reformers from other domains, but he also became dependent on new patrons for safety and opportunity.
