By 1333, the Kamakura shogunate (鎌倉幕府, Kamakura Bakufu) had governed Japan for 148 years. It had survived the deaths of the Minamoto (源) founding line and passed control to the Hojo (北条) regency, survived two Mongol invasions in the 1270s and 1280s, and outlasted any number of internal crises. It was the foundational institution of warrior government in Japan — the first time samurai had ruled in their own right, without the fiction of serving the imperial court. And it was exhausted.

Emperor Go-Daigo (後醍醐天皇) had spent years maneuvering against the Hojo regency, attempting to restore genuine imperial authority. His first revolt, the Genko War (元弘の乱), had failed in 1331, and he had been exiled to the Oki Islands (隠岐諸島). But the structure of Hojo power was cracking. Land disputes had created a generation of samurai with grievances. The shogunate's authority rested on the assumption that the warriors who served it had more to gain from loyalty than rebellion. By 1333, that assumption was no longer holding.

Into this moment walked Nitta Yoshisada (新田義貞), the 32-year-old lord of the Nitta family in Kozuke Province (上野国), carrying Minamoto bloodline credentials and a reputation as a capable but not especially prominent warrior. He had been summoned to join the Bakufu forces besieging Chihaya Castle (千早城), where Kusunoki Masashige (楠木正成) was conducting a brilliant guerrilla defense on behalf of the emperor. Yoshisada had no particular reason to rebel. He was a Bakufu vassal. He was expected to serve.

Instead, he obtained a secret imperial mandate from Go-Daigo's loyalists, feigned illness to excuse himself from the siege, and rode home to Kozuke. In late spring 1333, he raised the imperial banner at Ikushina Shrine (生品神社) with a small initial following. The act was either supreme audacity or a calculated reading of how much the Hojo's support had eroded. It was probably both.

What happened next confirmed his calculation. As Yoshisada marched south toward Kamakura, samurai who had been waiting for a reason to act came to him. Men with land grievances. Men who remembered slights from Hojo officials. Men who simply sensed that the old order was about to break and wanted to be on the right side of the fracture. His force swelled rapidly. Inconclusive fighting at Kotesashi (小手差原) on June 23 and a significant victory at Kumegawa (久米川) on June 24 built momentum. By the time he reached the approaches to Kamakura, he commanded an army.

Kamakura was not easy to take. The city was protected on three sides by steep hills and penetrated only through narrow mountain passes — Gokurakuji (極楽寺切通し), Kewaizaka (化粧坂切通し), and others — that defenders could hold against any frontal assault. Yoshisada tried them. They were blocked. His army was stopped.

He then led his force around the hills to the beach at Inamuragasaki Cape (稲村ヶ崎) on Sagami Bay (相模湾). The chronicle 太平記 (Taiheiki) records what happened next in verse that has echoed through Japanese memory for seven centuries: Yoshisada dismounted from his horse, removed his helmet, and prostrated himself at the water's edge. He prayed to Ryūjin (龍神), the dragon god of the sea, asking that the waters recede and open a path for his army. He threw his gold sword — a precious object, an act of total commitment from a man whose resources were not unlimited — into the surf.

The tide receded. Whether by divine intercession or the rhythms of Sagami Bay, the exposed beach was passable, and Yoshisada's army marched around the coastal cliffs into the city.

The siege of Kamakura lasted from June 30 to July 4, 1333. Yoshisada's forces set fire to the city. The last Hojo regent, Takatoki (北条高時), retreated to Toshoji Temple (東勝寺) with hundreds of his followers — warriors, family members, retainers — and they committed mass suicide together in a cave. Japan's first warrior government ended not in a battlefield defeat but in fire and collective death in a cave.

Yoshisada was 32 years old. He had never led a major campaign before this one. He would spend the next five years fighting for Emperor Go-Daigo's fragile Kenmu Restoration (建武の新政) before dying in battle in 1338, age 37, still in the field. He never saw the peace he helped create. But the Kamakura shogunate was gone, and the age that came after — the chaos of the Nanboku-cho period (南北朝時代), the rise of the Ashikaga, and eventually the Sengoku era — traces its origin to the morning he raised a banner at a small shrine and rode south.