Tokugawa Ieyasu

July 30, 1570 · 5,000 total casualties

The first time the Oda-Tokugawa alliance was tested in a genuinely difficult pitched battle rather than a surprise or a siege, and it held — the partnership between Nobunaga and Ieyasu, formalised years earlier, would outlast Nobunaga himself and eventually deliver Ieyasu the whole country. The Azai and Asakura were not destroyed here, which is why Nobunaga spent the next three years grinding them down instead.

January 25, 1573 · 3,000 total casualties

The one clean defeat any of the eventual unifiers suffered in a major pitched battle, and Ieyasu kept a portrait of his own humiliated, terrified face painted afterward, reportedly to remind himself never to be so reckless again. Shingen's death from illness a few months later, on the march, removed the one man capable of beating Nobunaga's alliance outright — Ieyasu's survival here was closer to accident than victory.

June 28, 1575 · 12,000 total casualties

Usually cited as the battle that ended the supremacy of the mounted samurai in Japanese warfare, arrived at independently and at almost exactly the same moment Europe was learning the identical lesson at Nieuwpoort and would relearn it again at places like Rocroi. It broke the Takeda clan's military capacity for good — Katsuyori's forces never recovered, and Takeda territory fell to Nobunaga's alliance within seven years.

March – November 1584 · 9,000 total casualties

The one campaign of the unification in which Ieyasu stands, briefly, on the losing side of the ledger — resisting the very centralisation he would complete sixteen years later. Hideyoshi, unable to win outright, made peace instead: Nobukatsu was brought to terms directly and Ieyasu, deprived of his ally's pretext, submitted formally without ever having been decisively beaten in the field. It is the clearest sign in the whole war that political settlement, not battlefield annihilation, was how Hideyoshi actually built his hegemony.

October 21, 1600 · 32,000 total casualties

Routinely ranked as the most important battle in Japanese history — 'the battle that determined the realm.' It replaced the Toyotomi settlement with Tokugawa supremacy in a single day and set up the shogunate Ieyasu formally founded three years later. Mitsunari's cause was, on paper, the legitimist one — defending the young Hideyori's inheritance against a subordinate's ambition — which is why the site frames the 'unifiers' label here as tracking whoever ends up governing Japan next, not moral legitimacy.

November 1614 – January 1615 · 20,000 total casualties

A siege decided by engineering fraud rather than battle. The negotiated truce specified filling in the outer moat; Tokugawa work crews filled in the inner moats as well while Toyotomi negotiators were occupied elsewhere, stripping the castle of the defences that had made the winter assaults so costly. It left Osaka Castle essentially indefensible for the campaign that followed within months.

June 3, 1615 · 100,000 total casualties

The end of the Toyotomi line and, with it, the last serious military resistance to Tokugawa authority. It closes the unification cycle exactly where it began — with the destruction of an entire clan and the killing of its heirs, the method Nobunaga and Hideyoshi had themselves used on the Azai, the Takeda, and the Hōjō, now turned by Ieyasu on Hideyoshi's own son. What followed was two hundred and fifty years without a major civil war, purchased by finishing the Sengoku period's logic all the way to its end.