The Kinmon Incident occurred when members of the Chōshū Domain, feeling threatened by the rising influence of the Satsuma and Aizu Domains, staged a bold attempt to seize power at the imperial court in Kyoto. The tensions had been escalating as the Tokugawa shogunate's authority weakened, with competing factions vying for control over the future direction of Japan. The Chōshū samurai, upstream in their ambitions, rallied their forces to confront the influential Satsuma and Aizu allies, who were gaining favor in the imperial court under the auspices of restoring the emperor's authority.

On the morning of the event, tensed Chōshū forces attempted to block access to the imperial court, sparking violent confrontations with the forces loyal to the Satsuma and Aizu Domains. The chaos witnessed the tragic loss of life on both sides, with the Chōshū faction ultimately being overpowered after fierce fighting. The aftermath of this incident led to increased hostilities, solidifying the alliance of the Satsuma and Aizu while isolating Chōshū. Consequently, this rift contributed to the broader conflicts that would culminate in the Boshin War, fundamentally shifting Japan's political landscape.

Moreover, the Kinmon Incident illustrated the intense factionalism that characterized the Bakumatsu period, setting the stage for the eventual collapse of the Tokugawa shogunate and its replacement by the Meiji government. The ideological battle of loyalty to the emperor versus allegiance to the shogunate was further entrenched in society, impacting diverse levels of Japanese life.