The Urado Uprising occurred in 1600 in Tosa Province in the aftermath of the Battle of Sekigahara. As a consequence of aligning with the defeated Western Army, the Chōsokabe clan were ordered by Tokugawa Ieyasu to be removed from their position as the sengoku daimyō of Tosa Province. The uprising was triggered when certain retainers of the clan opposed orders to vacate the base of the Chōsokabe at Urado Castle in the Agawa District of Tosa.
After the Battle of Sekigahara, Chōsokabe Morichika, the twenty-second head of the Chōsokabe clan, was removed from his position as a sengoku daimyō and banished before returning to Tosa. Morichika attempted through Ii Naomasa, a senior retainer of the Tokugawa with whom he was on friendly terms, to apologize to Ieyasu. Based on a letter from Naomasa, rather than have Tosa seized, Morichika planned to receive substitute territory as a form of forbearance and he ostensibly went to the capital for this reason.
According to historical accounts of Tosa, Morichika was removed from his position for murdering his older brother, Tsuno Chikatada, based on slander from a retainer named Hisatake Chikanao. This act angered Ieyasu who, in turn, removed Morichika from his position and seized his territory. In any event, it can be surmised that Morichika became answerable for the situation, for which the provision of a forbearance was scrapped and he was removed from his position. The consequences of the murder of Chikatada do not appear to have been raised as a reason for his removal.
Ieyasu dispatched a retainer of Naomasa as an emissary to Tosa with orders to seize Urado Castle. At the time of the seizure, retainers of Morichika who protested the loss of the seizure along with surviving retainers of the Kira and Tsuno clans launched the Urado Uprising, opposing transfer of the territory and main base of the Chōsokabe at Urado Castle. A total of 17,000 men surrounded the Sekkei Temple where the emissary lodged. Upset at the situation, Ieyasu ordered other daimyō in Shikoku to dispatch troops to assist. At this time, divisions arose within the Chōsokabe clan between senior retainers on one hand and peasant-samurai on the other regarding how to respond to the situation. This prompted some of the senior retainers to lock out of the castle the instigators of the uprising. On 12/1, the peasant-samurai supporting the uprising were defeated. As a result, on 12/5, the seizure of Urado Castle was completed.
This event marked the end of the status of the Chōsokabe as a daimyō family. The band of retainers dispersed, with some entering into service for other daimyō, some becoming rōnin, or wandering samurai, and some returning to peasant life. On 1/8 of Keichō 6 (1601), the new lord, Yamauchi Kazutoyo, entered Urado Castle. A total of 173 heads of participants in the uprisings were sent to Ieyasu at Ōsaka Castle while remnants from the uprising continued to be tracked down thereafter.
In the background, the uprising was a response to severe measures imposed on the Chōsokabe who were not advocates for the war, but this also reflected the unique system of military service by the Chōsokabe that incorporated peasant-farmers into a dual role as soldiers. This system, conceived by Morichika’s grandfather, Chōsokabe Kunichika, and defined by the group known as ichiryō-gusoku, ran counter to the policies of the central authorities (the Oda, Toyotomi, and Tokugawa administrations) who aimed for a separation of the roles of peasants and soldiers. The replacement of the Chōsokabe as the governing authority of Tosa by the Yamauchi clan who were retainers of the Oda and Toyotomi having no affinity to the province had a clear impact resulting in a loss by the peasant-samurai of their status. The event gave rise to two camps – one comprised of senior retainers whose status as bushi was recognized both inside and outside the clan and who were supportive of the suppression of the uprising triggered by seizure of castle and the second comprised of members of the ichiryō-gusoku who resisted owing to the fear of a loss of their status as bush (and thereby being relegated to the role solely as peasant-farmers).
As the new lord, Kazutoyo showed respect for the policies from the era of the Chōsokabe clan by welcoming some of the clan elders to serve as high-ranking retainers of the Tosa domain. Meanwhile, the separation between bushi and peasant-farmers remained incomplete, although, under the Yamauchi clan, peasant-samurai who formerly served the Chōsokabe clan saw their privileges reduced and became known as gōshi, a status inferior to the Yamauchi clan’s retainers.