Ieyasu belonged to the Tokugawa branch of the great Minamoto family, and the line of Shoguns which he founded thus became known as the Tokugawa Shoguns. This was the last line of Shoguns: it began with Ieyasu in 1603, when the title was conferred on him by the emperor; it ended in 1868, when the Shogunate was struck out of Japanese government.

Ieyasu had to go through the usual struggle before his power was established. There were always plenty of turbulent Daimyos ready to snatch some advantage for themselves upon a change of ruler, and these fierce lords banded against Ieyasu and strove to overthrow him.

The quarrel came to a head in 1600. Two vast armies stood face to face near the village of Sekigahara, to the east of Kyoto. The army of the banded chiefs was by far the greater, but it was composed of men from many provinces and led by many leaders. The other army was controlled by one man, and he a master of war. The combat was joined in the morning and raged all day long. Cannon were fired and matchlocks cracked, but the ancient weapons of sword and spear were the arms which decided the day, and the slaughter was tremendous. At evening the enemies of Ieyasu broke and fled, leaving him master of the field and master of Japan. This is one of the decisive battles in Japanese history. It ranks with the great sea-fight between Minamoto and Taira at Dan-no-ura; like that, it shaped the course of events for centuries.

For now that Ieyasu was firmly fixed in the seat of authority, he set on foot far-reaching measures which were to hold Japan in their grip for two hundred and fifty years. He had broken the power of the rebel Daimyos, and next he stripped many of them of a great part of their possessions and bestowed the land thus gained upon his own kinsmen and followers. In this way he made the Tokugawa family all-powerful in the State, and this formed the foundation of his strength. At the same time he acted in a peaceful and moderate way towards those who were willing to submit, and he took care not to offend the nation by overthrowing great and famous houses, whose roots were struck deeply into the soil. As regarded the Emperor, he paid him the deepest respect, and took care to obtain his consent to the assuming of the title of Shogun.

Up to the time of Ieyasu there had been only one capital in the country, the city of Kyoto. But the new Shogun now set up a capital of his own at Yedo, and henceforth, until recent times, there were two capitals as well as two rulers. The Emperor, or Mikado, and his Court dwelt at Kyoto; the Shogun, or Tycoon, and his Court dwelt at Yedo.

The rest of Ieyasu's life was spent as a law-maker rather than as a general. He devoted himself to labours which would uplift his people and improve his country. He was not a great scholar but he had a deep respect for letters. In the long ages of unending civil strife, learning had sunk to a low ebb. But now that the land was at peace, scholars and artists and poets began to appear, and Ieyasu became their patron. He had books printed, and he encouraged the Daimyos to open schools where the children of the Samurai could receive a good education as well as instruction in the use of arms. He lived until 1616, and left to his countrymen a code of laws or rules, written in one hundred chapters, and known as the Legacy of Ieyasu, a document which was held in great reverence after his death.