Note on dating: This entry follows the traditional Japanese lunar calendar, standard practice for events before Japan adopted the Gregorian calendar in 1873. The 12th day of the 5th month of 1333 corresponds to approximately July 2 in the Gregorian calendar, falling within the four-day siege of Kamakura (Gregorian June 30 to July 4, 1333).

The Kamakura shogunate (鎌倉幕府, Kamakura Bakufu) had ruled Japan since 1185, when Minamoto no Yoritomo (源頼朝, Minamoto no Yoritomo) established the first warrior government. By 1333, the institution had drifted far from its origins. Real power had long since passed from the Minamoto shoguns to the Hojo clan (北条氏, Hojo-shi), who held the title of regent (執権, shikken) and ruled in the name of puppet shoguns. It was a regime built on borrowed legitimacy, and everyone knew it.

The last Hojo regent was Takatoki (北条高時, Hojo Takatoki), who had come to power young and proved an ineffective ruler. He was known, among other things, for his obsessive patronage of dog-fighting — keeping hundreds of dogs and lavishing resources on organized bouts while governance deteriorated. Medieval chroniclers used him as a symbol of decadent failure, and the symbol was not entirely unfair.

Emperor Go-Daigo (後醍醐天皇, Go-Daigo Tenno) had spent years attempting to restore direct imperial rule, arguing that the shogunate's grip on power was an usurpation. The Hojo had exiled him to Oki Island (隠岐島, Oki-no-shima) in 1332. He escaped and began gathering supporters. Warriors across Japan watched which way the wind was blowing.

Nitta Yoshisada (新田義貞, Nitta Yoshisada) was not a famous general. He was a mid-ranking lord from Kozuke Province (上野国, Kozuke no Kuni, modern Gunma Prefecture), a descendant of the Minamoto line who had served the Kamakura shogunate faithfully for years. In mid-1333, the shogunate ordered him to collect a special tax. The timing was wrong, or the principle was, or perhaps it was simply the last straw. Nitta publicly renounced his loyalty to Kamakura, threw down his commission in the road, and raised the imperial standard for Go-Daigo. He was 32 years old. The decision took days. It changed Japan's history.

His forces swept across the Kanto plain with unexpected speed, gathering warriors who had been waiting for someone to move first. By the time Nitta reached the outskirts of Kamakura, he had an army. Kamakura itself was formidable: the city sat in a bowl of steep hills, accessible only through narrow mountain passes called kiridoshi (切り通し), and bordered on the south by the sea. It had never been successfully attacked from outside.

Nitta divided his forces into three prongs, attacking the mountain passes simultaneously to prevent defenders from concentrating. The tactic was sound, and it stretched Kamakura's defenders thin. Then came the coastal approach at Inamuragasaki (稲村ヶ崎, Inamuragasaki) — a sea cape that previous attackers had found impassable at high tide. The 太平記 (Taiheiki), the great chronicle of the era, records that Nitta rode into the surf and threw his golden sword into the sea as an offering to Ryujin (竜神, the sea god, god of the sea), praying for the tide to recede. The tide receded. Whether this was miraculous intervention or a commander's careful attention to tidal patterns, Nitta's forces moved along the exposed coastal flat and bypassed the mountain defenses entirely. The route that had stopped every previous attacker lay open.

Kamakura fell in approximately four days. The speed was shocking — contemporaries across Japan received the news with disbelief. The shogunate's allies in distant provinces had no time to organize a relief force. The collapse was not the product of overwhelming numbers; it was the product of a single defection that had shattered the regime's legitimacy before a sword was drawn.

Hojo Takatoki (北条高時, Hojo Takatoki), 29 years old, gathered his kinsmen, senior retainers, and their families and retreated to Toshoji (東勝寺, Toshoji), the Hojo family temple. There, approximately 870 men — the chronicle of the era gives the number as over 870 — performed 切腹 (seppuku, ritual self-disembowelment) together. They set the temple alight. The Kamakura shogunate, 148 years old, ended in fire and silence.

Emperor Go-Daigo returned from exile and attempted to rule directly in what became known as the Kenmu Restoration (建武の新政, Kenmu no Shinsei). He lasted three years. The warrior class that had destroyed one shogunate was not interested in returning to subordination under an emperor. Ashikaga Takauji (足利尊氏, Ashikaga Takauji), one of the generals who had helped topple Kamakura, turned against Go-Daigo and established the Ashikaga shogunate in 1338 — the same year Nitta Yoshisada died in battle, fighting for the emperor who had already lost. The lesson of Kamakura's fall was absorbed immediately: the man who defected first held the power.