More than 160,000 men had surrounded Osaka Castle (大坂城, Osaka-jo), and it was not enough.

Tokugawa Ieyasu (徳川家康, Tokugawa Ieyasu) was seventy-one years old. Behind him stretched fifty years of strategic patience, political maneuvering, and the occasional battlefield genius that had eliminated every rival Japan had ever produced. At Sekigahara in 1600, he had effectively ended the Sengoku era. In 1603, he had received the title of shogun. In 1605, he had passed it to his son Hidetada (徳川秀忠, Tokugawa Hidetada) to demonstrate that the Tokugawa line would hold power permanently. He had done everything a man in his position was supposed to do.

And yet Osaka Castle refused to fall.

The castle had been built by Toyotomi Hideyoshi (豊臣秀吉, Toyotomi Hideyoshi) — Ieyasu's predecessor and, in many ways, the template he could never quite escape. Hideyoshi had designed the fortress as an architectural argument: a concentric system of moats, stone walls, and elevated keeps that turned every approach into a killing ground. Now Hideyoshi's son, Toyotomi Hideyori (豊臣秀頼, Toyotomi Hideyori), twenty-one years old and the last serious rival to the Tokugawa claim on Japan, held it.

With him stood roughly 90,000 to 100,000 defenders — many of them ronin (浪人, ronin), masterless samurai who had lost their lords in the Tokugawa consolidation and had nothing to gain from a Tokugawa victory. They had crossed the country for this. Some had followed famous names; others had come simply because Osaka Castle was the one place in Japan that still offered them a purpose.

The most dangerous of them had built his own fortress.

Sanada Yukimura (真田幸村, Sanada Yukimura), approximately forty-seven years old and already legendary among warriors of his generation, had constructed the Sanada-maru (真田丸, Sanada-maru) — an earthwork redoubt extending from the castle's southwestern corner, positioned to catch attackers in interlocking fields of musket fire. The Tokugawa hurled regiment after regiment at the Sanada-maru and were repelled with heavy casualties each time. Yukimura's forces sortied from the earthwork repeatedly, breaking through the Tokugawa siege lines, disrupting the encirclement, and making an already humiliating stalemate worse. The siege had been underway since December 4, and the most powerful military force ever assembled in Japan could not make meaningful progress against one determined section of the outer defense.

By December 15, the situation had settled into a grinding, expensive impasse. Ieyasu's envoy Honda Masazumi (本多正純, Honda Masazumi) had exchanged letters with Toyotomi negotiators on December 8 and December 12, but talks had stalled. Both sides were feeling the cost — the Tokugawa in logistics, mounting casualties, and the embarrassment of visible failure; the Toyotomi in dwindling supplies and the awareness that they could survive a siege but not win it.

On December 16, the shogunate moved to break the psychological stalemate. A hundred cannon and matchlock arquebuses opened up on the castle simultaneously — a scale of bombardment Japan had never witnessed. Among the guns were Dutch and English-made cannon of a range and power that castle walls had not been designed to withstand. A shot struck the Tenshu (天守, Tenshu), the main castle keep, penetrating its walls and killing several women — attendants of Yodo-dono (淀殿, Yodo-dono), Hideyori's mother — who had sheltered there believing the keep to be safe. The sound and the casualties shook the defenders. Yodo-dono, according to accounts, was particularly frightened.

The Toyotomi agreed to negotiate in earnest.

Honda Masazumi concluded a truce around December 20, 1614. The terms seemed reasonable. The outer moats would be filled as a gesture of good faith; hostilities would end. Honda Masazumi later said that the workmen filling the moats had misunderstood their instructions and filled both the outer and inner moats rather than only the outer ones.

Most historians believe this was planned from the beginning.

Osaka Castle without its inner moats was no longer the impregnable fortress Hideyoshi had built. It was simply a large fortification on flat ground, surrounded by walls that Tokugawa artillery could reach and Tokugawa troops could storm. The Winter Siege (冬の陣, Fuyu no Jin) had failed to take the castle by force. It succeeded in stripping the castle of everything that had made it unconquerable.

The Summer Siege (夏の陣, Natsu no Jin) came in May and June of 1615. It lasted less than two weeks. On June 4, the castle fell. Toyotomi Hideyori and his mother Yodo-dono committed suicide in the burning keep. The Toyotomi line was extinguished.

On December 15, 1868 — exactly 254 years later — the last die-hard samurai loyalists of the collapsed Tokugawa shogunate held an election at Goryokaku (五稜郭, Goryokaku) fortress on Hokkaido, choosing Enomoto Takeaki (榎本武明, Enomoto Takeaki) as president of what they called the Republic of Ezo (蝦夷共和国, Ezo Kyowakoku). Former shogunate warriors, having lost the Boshin War, founded Japan's first elected government in its northern wilderness. It lasted five months before Meiji forces crushed it. The first Japanese election was held by the last samurai who refused to accept that their world was over.