He told his generals he would take the field himself.

The announcement came in the great hall of 大坂城 (Osaka-jo) after the army returned from 鳥羽・伏見の戦い (Toba-Fushimi no Tatakai) — the Battle of Toba-Fushimi — which had ended in four days of catastrophic defeat. On paper, the shogunate's forces had overwhelming advantages: roughly 15,000 men against an imperial army one-third that size, a fortified supply base at Osaka Castle, and the weight of institutional authority behind them. In practice, they had been shattered.

The imperial forces fighting under the banner of the restoration had Armstrong howitzers, Minié rifles, and Gatling guns — weapons purchased and imported from Europe and America. More importantly, they had raised the imperial banner above their lines. For samurai on the shogunate side, firing on the Emperor's flag meant being classified as a traitor to the throne. When that banner went up, units began to waver and then break. The shogunate army outnumbered its opponents three to one and still lost. By January 31, 1868, it was over.

徳川慶喜 (Tokugawa Yoshinobu) retreated to Osaka Castle with what remained of his force and summoned his commanders. According to multiple accounts, he spoke of continuing the fight, of leading a counteroffensive personally. His men believed him. Then, on the evening of January 31 into February 1, he left.

He went quietly, taking with him only the 大名 (daimyo) of Aizu (松平容保, Matsudaira Katamori) and the daimyo of Kuwana (松平定敬, Matsudaira Sadaaki) — two loyal lords who had been at his side throughout the crisis. They made their way to the water. His warship, the 開陽丸 (Kaiyo-maru), was supposed to be waiting in Osaka Bay. It was not there.

So the fifteenth shogun of Japan, the last head of the dynasty founded by 徳川家康 (Tokugawa Ieyasu) in 1603, rowed out in the darkness and boarded the USS Iroquois — a 1,016-ton American steam sloop-of-war belonging to the US Asiatic Squadron, which had been observing the conflict from the bay. The crew had received no advance warning that they were about to host the commander of one of the world's largest governments. Yoshinobu spent roughly two hours on the American deck until the Kaiyo-maru arrived. Then he transferred to his own ship and sailed east toward Edo.

At dawn on February 1, the soldiers inside Osaka Castle learned that their commander had gone in the night.

The castle burned. Retreating Tokugawa troops set fire to the structure before dispersing — a gesture that looks, in retrospect, less like a military decision and more like an expression of what it feels like to be abandoned. 大坂城 (Osaka-jo), the fortress that Toyotomi Hideyoshi had originally raised in the 1580s and the Tokugawa had rebuilt after their own siege in 1615, was one of the most potent symbols of military power in Japan. It was reduced to ash by the men who were supposed to defend it. Imperial forces occupied the ruins on February 2.

Yoshinobu sailed to Edo and entered voluntary confinement at 寛永寺 (Kan'eiji), a great temple complex in Ueno. He issued no orders for resistance. Without his authorization, the shogunate's military apparatus — still substantial, spread across the country — had no central command. The 戊辰戦争 (Boshin Senso), the Boshin War, would continue in the north and at the Goryo-kakubu fort in Hakodate through 1869, but as an institutional force, the Tokugawa shogunate effectively ceased to exist the moment Yoshinobu stepped off that rowboat.

He formally surrendered in April 1868. Edo was transferred to imperial forces without significant bloodshed — the "bloodless surrender of Edo" — largely because Yoshinobu refused to authorize resistance. The city that would become Tokyo was spared the destruction that had consumed Osaka Castle.

What happened to Yoshinobu himself is, in its own way, stranger than the escape. He was not executed. He was not imprisoned. He was confined to his estate in Shizuoka — the same city, it should be noted, where 徳川家康 (Tokugawa Ieyasu), the first shogun, had spent his own later years after passing power to his son. Yoshinobu took up photography and cycling and billiards. He hunted. He read. He was granted the rank of prince in 1902. He died in 1913 at age seventy-six, outliving the Meiji Emperor himself by a year.

The shogunate lasted exactly 265 years — from Ieyasu's appointment in 1603 to Yoshinobu's midnight escape in 1868. It began with a patient man born at Okazaki Castle on January 31, 1543, who waited sixty years to take power. It ended with his descendant rowing away in the dark because his ship was two hours late.