Toyotomi Hideyoshi’s death transformed a unified realm into a regency whose rules could not restrain the ambitions of its most powerful lords. With his heir Yaemon still a child, five regents were charged with ruling in his name; in practice, power centered on Toranaga and Ishido, whose competing claims of loyalty to the late ruler sharpened the danger of civil war.

From Unification to Regency

The Taikō’s rule followed decades of upheaval. About thirty-five years before the present struggle, Goroda took Kyoto and spent the next two decades subduing roughly half of Japan. After Goroda was assassinated by one of his generals, power passed to Nakamura, his chief vassal and most brilliant commander. With Toranaga, Ishido, and others helping him, Nakamura defeated Goroda’s descendants and brought the whole realm under one ruler for the first time.

Nakamura’s origins shaped the titles through which he governed. Born a peasant, he could not claim the highest status available to a ruler of the realm. He accepted the title of Kwampaku, later passing it to his son, and took the title of Taikō for himself. Even Toranaga bowed to him. His achievement was not merely a change of personnel: it brought twelve years of complete peace after centuries of civil war. The Taikō’s death the previous year removed the authority around which that settlement had held together.

The Heir and the Regents’ Authority

The regency was meant to preserve the Taikō’s rule until Yaemon came of age. Toranaga maintained that the heir would inherit at fifteen, eight years later, and that the five regents were to govern in his name until then. The arrangement gave the council a legal mandate, but not equal practical power: Toranaga and Ishido were the only regents with substantial independent influence. Their rivalry therefore ran through the very institution intended to prevent a succession struggle.

Toranaga portrayed himself as a defender of the Taikō’s peace, insisting that he would not be the first to break it. He also argued that the realm had already split into an eastern and a western camp, that the council was divided, and that a body unable to govern even a small village could not rule an empire. His public language joined a pledge of restraint to a warning about treachery. Ishido, for his part, treated Toranaga’s preparations and family connections as signs of a bid for power. Each could claim to defend the dead ruler’s settlement while presenting the other as the threat to it.

The dispute extended to Toranaga’s family alliances. He had arranged marriages linking his son and granddaughters to powerful houses, including those of Lord Masamune, Lord Zataki, and Lord Kiyama. Ishido argued that these ties violated the Taikō’s instructions. Toranaga answered that the restrictions concerned marriages threatening the succession of the Taikō’s house, not ordinary connections between leading families, and denied seeking either additional territory or Yaemon’s inheritance. The argument exposed the weakness of rules whose meaning depended on the regents’ competing interpretations.

Hostages, Votes, and Political Isolation

The Taikō’s settlement also forbade regents from taking one another’s hostages. Ishido accused Toranaga of violating that rule because Lady Ochiba, Yaemon’s mother, was in Toranaga’s city of Yedo while Toranaga remained in Osaka. Toranaga described her presence as a family visit: her sister was in labor and married to his son and heir. Ishido instead treated her absence from Osaka as a matter of political security and demanded that she return.

The accusation became dangerous when Ishido announced that three other regents—Sugiyama, Onoshi, and Kiyama—supported his position and would wait in Osaka until Lady Ochiba came back. Toranaga had previously managed the council so that its votes divided two to three; neither he nor Ishido had secured a four-to-one decision against the other. The new alignment threatened to leave Toranaga isolated, and the defection of Onoshi and Kiyama raised the question of what had induced former enemies to join Ishido. A procedural majority was thus more than a tally: it could decide whether Toranaga remained a participant in government or stood exposed to his opponents.

The clash between official duty and personal allegiance appears beyond the council as well. Yabu tells Toranaga that he is glad not to be a regent and that he has chosen to be Toranaga’s vassal freely. His declaration makes visible the political force of personal bonds: the dead ruler’s testament and the boy’s claim remain important, but retainers also choose sides according to their relationships with living lords. The regency is consequently vulnerable not only to open defiance but to competing definitions of loyalty.

The Peace Unravels

The political crisis changes the meaning of preparation. Toranaga argues that a wise ruler must prepare for treachery, even while maintaining that he will not initiate war. Around him, doubts about the council’s ability to preserve unity coexist with the assertion that the Taikō’s peace remains binding. The gap between those positions is where the prospect of conflict grows: preparations can be presented as caution by one side and proof of aggression by another.

Yabu’s response to the arrival of a foreign ship shows how the struggle could also alter military practice. The captured cargo gives him an unexpected store of weapons, including five hundred muskets and twenty cannon. He orders the armament moved secretly to his castle at Mishima and imagines a trained body of five hundred musket-armed samurai supporting twelve thousand conventional troops. That plan challenges Bushido’s traditional preference for individual combat and the sword, since firearms had been regarded as dishonorable as well as less accurate than bows. Later, a demonstration of disciplined ranks firing in rotation shows the tactical promise of coordinated volleys: even after the musketeers appear to flee from charging samurai, they regroup in a V and resume firing. The demonstration makes clear that new weapons could unsettle an established warrior order as well as change the balance between rival lords.

The death of the Taikō therefore marks neither a simple transfer of authority nor an immediate declaration of war. It leaves a child heir protected by a divided council, a peace invoked by opponents who distrust one another, and rules whose enforcement depends on the very lords contesting their meaning. The regency’s central contradiction is that it must rely on the cooperation of powerful rivals to preserve the unity that their rivalry is breaking apart.