The Shimabara Rebellion (島原の乱 Shimabara no ran) was an uprising in what is now Nagasaki Prefecture in southwestern Japan lasting from December 17, 1637, to April 15, 1638, during the Edo period. It largely involved peasants, most of them Catholics.
It was one of only a handful of instances of serious unrest during the relatively peaceful period of the Tokugawa shogunate's rule. In the wake of the Matsukura clan's construction of a new castle at Shimabara, taxes were drastically raised, which provoked anger from local peasants and rōnin (samurai without masters). Religious persecution of the local Catholics exacerbated the discontent, which turned into open revolt in 1637. The Tokugawa Shogunate sent a force of over 125,000 troops to suppress the rebels and, after a lengthy siege against the rebels at Hara Castle, defeated them.
In the wake of the rebellion, the Catholic rebel leader Amakusa Shirō was beheaded and the prohibition of Christianity was strictly enforced. Japan's national seclusion policy was tightened and official persecution of Christianity continued until the 1850s. Following the successful suppression of the rebellion, the daimyō of Shimabara, Matsukura Katsuie, was beheaded for misruling, becoming the only daimyō to be beheaded during the Edo period.
In the mid-1630s, the peasants of the Shimabara Peninsula and Amakusa, dissatisfied with overtaxation and suffering from the effects of famine, revolted against their lords. This was specifically in territory ruled by two lords: Matsukura Katsuie of the Shimabara Domain, and Terasawa Katataka of the Karatsu Domain. Those affected also included fishermen, craftsmen and merchants. As the rebellion spread, it was joined by rōnin (masterless samurai) who once had served families, such as the Amakusa and Shiki, who had once lived in the area, as well as former Arima clan and Konishi retainers. As such, the image of a fully "peasant" uprising is also not entirely accurate.
Shimabara was once the domain of the Arima clan, which had been Christian; as a result, many locals were also Christian. The Arima were moved out in 1614 and replaced by the Matsukura. The new lord, Matsukura Shigemasa, hoped to advance in the shogunate hierarchy, and so he was involved with various construction projects, including the building and expansion of Edo Castle, as well as a planned invasion of Luzon in the Spanish East Indies (today a part of the Philippines). He also built a new castle at Shimabara. As a result, he placed a greatly disproportionate tax burden on the people of his new domain and further angered them by strictly persecuting Christianity. The policies were continued by Shigemasa's heir, Katsuie.