The , also known as the , was a civil war fought in Japan between the Emperor Go-Daigo and the Kamakura Shogunate from 1331 to 1333. The Genkà  War was named after Genkà Â, the Japanese era corresponding to the period of 1331 to 1334 when the war occurred.
Go-Daigo became Emperor of Japan in 1318 and sought to remove the Kamakura Shogunate, which had ruled Japan as a de facto military government from the city of Kamakura since the Genpei War in 1185, and restore power to civilian government under the Imperial House in Kyoto. The Kamakura Shogunate was indirectly ruled by the Hà Âjà  clan as shikken â the regents of the Shà Âgun â and actively blocked the Emperor's manoeuvres to restore Imperial rule.
In 1331, Go-Daigo plotted to seize power through force and overthrow the Kamakura Shogunate by encouraging his vassals and other anti-Hà Âjà  samurai to rebel. However, Go-Daigo was betrayed when his trusted adviser Fujiwara Sadafusa alerted the shogunate, who dispatched troops to Kyoto to suppress the uprising. Go-Daigo fled Kyoto with the Sacred Treasures and sought refuge in Kasagi, a secluded monastery overlooking the Kizu River. Go-Daigo managed to escape Kasagi when it was attacked by Kamakura troops in the Siege of Kasagi, but was soon apprehended. Go-Daigo was subsequently exiled to the Oki Islands and the Kamakura then enthroned Emperor Kà Âgon, the first Emperor of the "Northern Court", setting the stage for the upcoming Nanboku-chà  period. Go-Daigo's son Prince Morinaga continued to fight against the Kamakura, leading his father's supporters alongside Kusunoki Masashige.
In 1333, Go-Daigo escaped Oki two years after his exile with the help of , raising a new Imperial army at Mount Senjà  in Hà Âki Province, in the modern town of Kotoura, Tottori Prefecture. He defeated the forces of Sasaki Kiyotaka at the Battle of Mount Senjà Âsan and gained the support of many warlords in western Japan against the Hà Âjà Â. Meanwhile, Ashikaga Takauji, the chief general of the Hà Âjà Â, was dispatched west to fight against Go-Daigo's second uprising. However, for unknown reasons, Takauji defected to Go-Daigo's army shortly before reaching Kyoto, and began to fight against the Hà Âjà Â. The reason for Takauji's defection is unknown, but assumed to be because of his unofficial leadership of the Minamoto clan, the victors of the Genpei War and arch-rivals of the former Taira clan to which the Hà Âjà  had belonged. Additionally, Takauji possibly hoped of being named Shà Âgun by Go-Daigo after his restoration to power. The Imperial army lifted the Siege of Chihaya and Imperial general Nitta Yoshisada won a string of victories in the Kà ÂzukeâÂÂMusashi campaign in May, including the Siege of Chihaya, the Battle of Kotesashi, the Battle of Kumegawa, and the Battle of Bubaigawara. The Kamakura Shogunate was eventually defeated at the Siege of Kamakura in early July, when Imperial forces entered the destroyed city and the Hà Âjà  committed suicide.
Go-Daigo triumphantly returned to Kyoto and claimed power from Emperor Kà Âgon in what came to be known as the Kenmu Restoration. Go-Daigo's rule would only last three years as his policies disillusioned his supporters, and most of the accomplishments of the Genkà  War were gradually undone. Many samurai who had fought for Go-Daigo were dissatisfied with their rewards, and his pursuit of consolidating Imperial power led to their subsequent exclusion from political affairs, whereas they had held significant influence under the shogunate. Japanese commoners were similarly dissatisfied as Go-Daigo failed to address the issues they had petitioned for him to resolve. In 1336, Ashikaga Takauji named himself the Shà Âgun and seized power from Emperor Go-Daigo, establishing the Ashikaga Shogunate based on the Kamakura system and marking the beginning the Nanboku-chà  "Northern and Southern Courts" period.