The Satcho Alliance refers to a historical agreement between the Satsuma Domain and the Choshu Domain in Japan during the late Edo period. This alliance was formed in 1866 to strengthen their military and political power against the ruling Tokugawa shogunate. The collaboration played a crucial role in the eventual overthrow of the shogunate and the restoration of imperial rule. The Satcho Alliance was significant in the lead-up to the Meiji Restoration, which began in 1868. By uniting their forces, the Satsuma and Choshu domains were able to coordinate efforts, share resources, and rally support from other factions. This cooperation ultimately contributed to the modernization and transformation of Japan into a more centralized and powerful nation.