It had ruled Japan for a century and a half. The Kamakura shogunate (鎌倉幕府, Kamakura Bakufu), founded by Minamoto no Yoritomo (源頼朝, Minamoto no Yoritomo) in 1185, had transformed the warrior class from an instrument of the imperial court into the de facto government of Japan. The Hojo regents (北条氏, Hojo-shi) who came to dominate it had survived the Mongol invasions, court conspiracies, and a dozen smaller rebellions. It seemed immovable.

In the spring of 1333, it began to move — downward.

The crisis had roots in the ambitions of Emperor Go-Daigo (後醍醐天皇, Go-Daigo Tennō), who had spent years attempting to restore direct imperial rule and overthrow the shogunate. He had failed once before and been exiled to Oki Island in 1332. But his loyalists fought on in his name, and in early 1333 one of them — an obscure steward from Harima Province named Akamatsu Norimura (赤松則村, Akamatsu Norimura) — raised an army and began marching toward Kyoto.

Norimura was not a major figure. He was a jito (地頭, jitō) — a provincial steward the Kamakura system had long overlooked and underpaid. Perhaps that made him reckless. He declared for Go-Daigo and rode toward the capital, and the Rokuhara Tandai (六波羅探題, Rokuhara Tandai) — the shogunate's permanent two-commander headquarters in Kyoto, responsible for policing the imperial court and the western provinces — sent out an army to stop him.

On approximately March 27, 1333, that army met Norimura at the Battle of Maya (摩耶の戦い, Maya no Tatakai). It was defeated.

The Rokuhara sent another force. It was defeated too. In the weeks that followed, Rokuhara commanders dispatched army after army westward through the mountain corridors approaching Kyoto — at Sakabe (坂部, Sakabe), at Segawa (瀬川, Segawa), and finally at Yamazaki (山崎, Yamazaki) at the very edge of the capital. Each army that went out came back broken or didn't come back at all. Norimura's forces, fighting on familiar terrain with the momentum of rebellion, outmaneuvered every response the shogunate made.

Two days' march to the south, on the slopes of Mount Kongo (金剛山, Kongō-san), the situation was no better. Kusunoki Masashige (楠木正成, Kusunoki Masashige) held Chihaya Castle (千早城, Chihaya-jō) with a garrison of a few hundred men against a shogunate army numbering in the thousands. Masashige had no intention of fighting conventionally. He dressed straw dummies in armor and propped them on the walls to draw enemy arrows. He rigged logs to roll down slopes onto attacking formations. He sent sorties at night to disrupt siege works. The shogunate's main army, which should have crushed Chihaya in days, spent months freezing on a mountainside while the rest of Japan began to tilt.

The Rokuhara commanders knew what was happening. Their messages to Kamakura — days away by horseback — asked for reinforcements, for direction, for a strategy that hadn't already been tried. The answers came too slowly to matter. In the institutional paralysis of a government that had never faced simultaneous collapse on two fronts, the decisions that needed to be made in hours were made in weeks.

The final blow came from within. The shogunate dispatched Ashikaga Takauji (足利尊氏, Ashikaga Takauji), one of its most prominent military commanders, with a large army to suppress Go-Daigo's loyalists. Takauji used the commission to recruit broadly, raised a formidable force — and then turned it against his employers. On June 20, 1333, he attacked and captured the Rokuhara headquarters. The two Rokuhara commanders fled Kyoto without a battle; they simply ran, knowing the position was lost.

At Kamakura, the shogunate's capital, the end came weeks later. Nitta Yoshisada (新田義貞, Nitta Yoshisada) led an army through the narrow coastal passes and into the city. The Hojo regent Takatoki (北条高時, Hojo Takatoki) and hundreds of his followers retreated to Toshoji Temple and committed suicide together. The 148-year-old Kamakura shogunate was over.

What Go-Daigo got next was not what he expected — but that is a different story. The Kenmu Restoration (建武の新政, Kenmu no Shinsei) lasted less than three years before Ashikaga Takauji, the man who had helped topple Kamakura, turned against the Emperor and founded his own shogunate. The warrior class that had been overthrown simply reorganized under different management.

But in the spring of 1333, in those early days of April when the Rokuhara commanders were still sending armies west and watching them fail, none of that was visible. What was visible was the arithmetic: fewer soldiers each time, the same mountain passes, the same result.