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1285-12-17
Kamakura (present-day Kamakura, Kanagawa Prefecture)
About 12 min read
The Shimotsuki Disturbance was a political upheaval that occurred on November 17, 1285 (8th year of Kōan), when Adachi Yasushige, a gokenin of the Kamakura Shogunate, was destroyed along with his entire clan by Taira no Yoritsuna, the internal administrator. "Shimotsuki" is an alternate name for the eleventh lunar month, and the incident was named after the month in which it occurred. This coup is recorded in history as a major event that solidified the Hōjō Tokusō family's autocratic rule while deepening divisions within gokenin society and forming a distant cause of the Kamakura Shogunate's decline.
Following the death of Hōjō Tokimune, the 8th Regent, the Kamakura Shogunate experienced rapid internal division. Tokimune had been a heroic leader who repelled the Kōan Campaign (the second Mongol invasion) in 1281, but died suddenly at the young age of 34 in 1284. His successor, Hōjō Sadatoki, the 9th Regent, was only 14 years old, and actual power rested with Adachi Yasushige, Sadatoki's maternal grandfather, and Taira no Yoritsuna, the steward (internal administrator) of the Hōjō Tokusō family.
Adachi Yasushige promoted political reforms known as "Kōan Virtuous Administration," seeking to alleviate the economic hardship faced by gokenin following the Mongol invasions and to curb the autocratic rule of the Tokusō family. This reform, aimed at resolving territorial disputes and restoring the status of gokenin, was supported by a broad range of gokenin, but was fundamentally incompatible with Taira no Yoritsuna's goal of strengthening the power of the Tokusō family.
On November 17, 1285, Taira no Yoritsuna accused Adachi Yasushige of treason to Hōjō Sadatoki and attacked the Adachi clan with the Shogunate's forces. Caught off guard, Adachi Yasushige committed suicide, and many of his clansmen were killed. It is said that over 500 Adachi clan members and allied gokenin were killed or executed, and that the streets of Kamakura were drenched in blood in a single day.
Yoritsuna confiscated the Adachi clan's territories and dissolved their retainers. Thus, the Adachi clan, one of the most powerful gokenin forces, was destroyed overnight, and Taira no Yoritsuna became the de facto dictator of the Shogunate.
The Shimotsuki Disturbance is significant in understanding the role of swords during the Kamakura period. The Kamakura period was a time of rapid development in Japanese sword technology, with master swordsmiths active primarily in Bizen and Yamashiro provinces. Schools such as the Rai, Osafune, and Awtaguchi competed to forge renowned blades, which gokenin eagerly acquired.
It is believed that Adachi Yasushige, as a powerful gokenin, owned swords of the highest standard of his time. Swords owned by gokenin were not merely weapons but symbols of family status and authority, and were also used as gifts when establishing master-vassal relationships. When the Adachi clan was destroyed during the Shimotsuki Disturbance, their swords were confiscated or dispersed, and some are presumed to have passed into Yoritsuna's hands.
Swordsmiths of the Kamakura period such as Norikuné, Motoshige, and Osafune Kagemitsu were active during this era, and the blades they forged before and after the Shimotsuki Disturbance passed into the hands of the Shogunate's warriors, helping to forge a turbulent age. Swords that saw actual combat on the battlefields of the Mongol invasions were subject to performance demands that elevated the importance of longer blades such as naginata and nodachi, while the katana remained in high demand as a personal defense weapon and symbol of authority.
After the Shimotsuki Disturbance, Taira no Yoritsuna held absolute power within the Shogunate. However, his despotism, which exceeded his position as steward of the Tokusō family, did not last long. In 1293, Yoritsuna was likewise purged by Hōjō Sadatoki (the Taira Zenmon Rebellion). Sadatoki, wary of Yoritsuna's despotism, executed him at the instigation of Yoritsuna's eldest son, Munenaga, who had informed against his father.
Thus, the power structure of the Kamakura Shogunate underwent significant transformation through this series of coups from the Shimotsuki Disturbance to the Taira Zenmon Rebellion. Though the Tokusō autocracy was established, the Shogunate, having lost the support of the broad gokenin, gradually lost its basis for legitimacy.
The Shimotsuki Disturbance holds important significance in Japanese history for the following reasons.
First, this coup accelerated the establishment of the Tokusō autocratic system. With the destruction of the Adachi clan, a powerful counterbalance among the gokenin, the power of the Hōjō Tokusō family had no equal. However, the Shogunate paid the price of losing the allegiance of the broad gokenin who supported it.
Second, it served as a catalyst for the exhaustion and discontent within gokenin society following the Mongol invasions to erupt. The failure of Adachi Yasushige's "Kōan Virtuous Administration" cut off gokenin hopes for political relief and accumulated discontent toward the Shogunate. This accumulated discontent became a distant cause of later movements to overthrow the Shogunate.
Third, this incident demonstrated the danger of "gekokujō" (the lower overturning the higher) in warrior society. The fact that Taira no Yoritsuna, in the position of steward, held power rivaling that of his lord and destroyed the Adachi clan, an affinal family of the Tokusō house, was an event that shook the very foundations of the master-vassal relationship.
Half a century after the Shimotsuki Disturbance, in 1333, the Kamakura Shogunate fell to the overthrow movement of Emperor Go-Daigo and the attack on Kamakura led by Nitta Yoshisada. Historians regard the Shimotsuki Disturbance as one of the distant causes of this collapse. The division of gokenin society, resentment toward Tokusō autocracy, and economic hardship following the Mongol invasions combined to bring about the Shogunate's collapse, and the Shimotsuki Disturbance was the beginning of that chain of events.
Even in modern times, the Shimotsuki Disturbance is regarded as an important event in Kamakura period history and is an essential historical source and subject of study in research on the power structure of the Kamakura Shogunate and the gokenin system. Including the sword culture that lay behind it, this coup is a historical mirror that deeply illuminates the essence of warrior society.