Nobunaga was a Daimyo, but not one of the highest rank. His property was small, but he was not slow in enlarging it at the expense of his neighbours. His retainers formed a body of well-drilled troops, he himself was a skilful general, and, above all, he had Hideyoshi as his right-hand man. Hideyoshi was at first a simple soldier in the service of his lord, but his talents for war were of so high an order that he soon rose to the position of second in command. In this place he was of immense service to Nobunaga. He was so full of cunning ideas, so clever in handling troops, so swift to devise plans which would throw the enemy into confusion, that it was said that the coming of Hideyoshi to the aid of an army was as good as adding ten thousand men to its ranks.

The power of Nobunaga grew rapidly, and at last there came to him an opportunity which he gladly seized. The Ashikaga Shoguns were ruling very badly, and one of them was murdered; a younger brother of the murdered man asked Nobunaga to help him to become Shogun, and Nobunaga leapt at the alliance.

He marched to the capital with a large army and placed his candidate in the office of Shogun. The Shogun induced the emperor to confer on Nobunaga the title of Vice-Shogun, and Nobunaga, with the aid of Hideyoshi, busied himself in restoring the capital to order.

Nobunaga now marched against some great lords who had not submitted to the authority of the new Shogun, and in this campaign he was assisted by Hideyoshi and by Ieyasu, a man belonging to a branch of the great Minamoto clan, and destined himself to become the founder of a great line of Shoguns. Nobunaga overthrew this group of his enemies, but was soon called upon to combat fresh foes who were marching on the capital and were backed up by powerful allies. These allies were the Buddhist monks of a great monastery which stood a few miles from Kyoto. The Buddhist priests and monks were often not only a religious but also a political and military force. They bore arms and were famous as fighting men: a large monastery could put a strong body of troops in the field.

The monastery near Kyoto was of immense size, a small city in itself. It contained three thousand buildings, and its army of warrior monks had been in the habit of taking liberties with the government of the capital a few miles away. The Buddhists chafed under the strict rule of Nobunaga and gladly gave aid to his enemies, furnishing them with shelter and supplies as they moved upon Kyoto. But Nobunaga hemmed in his foes so cleverly that they were glad to beg for peace and to retire to their own provinces. Then Nobunaga turned upon the monastery and took a terrible revenge. He burned it to the ground, slew great numbers of the monks, and drove the rest into exile. This was in 1571: from henceforth there was no love lost between Nobunaga and the Buddhist monks.

Nobunaga now began to show much favour to the Christians. He had not the smallest idea of becoming a Christian himself, but he thought the Christian faith would form a good balance to the Buddhist, and so strengthen his power. He built Christian churches, and the faith rose to great prosperity under his patronage. In 1573 he deposed the last of the Ashikaga Shoguns and took the authority of a Shogun into his own hands; now he ruled Japan in the name of the emperor, and ruled wisely and well.

But the powerful Daimyo of Chosu refused to own the authority of Nobunaga. In 1578 the ruler sent Hideyoshi to subdue the district, and for five years Hideyoshi waged war and conquered five provinces for his master. The final step of the long campaign was the capture of a great and powerful castle. Hideyoshi arrived before it, and the garrison laughed at him in defiance. The fortress was surrounded by lakes, and an attack by a large body of troops was impossible. But the besieged did not know Hideyoshi. He made no assault at all. Just below the castle a river carried off the water of the lakes. Hideyoshi ordered his troops to build a huge dam across the river and drown his enemies out. The dam was built and the water began to creep up the castle walls: Hideyoshi calmly waited for the fortress to surrender.

While this was going on, Nobunaga was marching with fresh troops to the aid of his famous general. He sent his army straight to the besieged castle, but he himself went by a less direct route, and called at the capital on his way. In Kyoto he stayed for a few days in the temple of Honnoji, intending to follow his troops. Now among the generals of Nobunaga there was one named Akechi, and Akechi bore a deep grudge against his chief. It arose from Nobunaga's fondness for rough jokes. One day there had been a great feast in his palace and Nobunaga became over-merry; he seized Akechi, took the general's head under his arm and rattled upon the head with his fan, as if playing a drum. This upsetting of his dignity gave mortal offence to Akechi, and he never forgave Nobunaga. Suddenly on their march to the castle he ordered his troops to turn aside and make for the capital. His captains asked him in surprise what this meant, and he replied grimly, "My enemy is in the Honnoji." Then he gained their aid by promising great rewards, and they marched with him against Nobunaga and the few guards who formed the ruler's escort.

Nobunaga was aroused by the attack on the temple. He looked out of a window, knew the traitors, and knew also that they sought his life. He made the best fight he could, but soon saw that the contest was hopeless. So he prepared to take his own life, for a Japanese gentleman must not suffer the dishonour of death at the hands of an enemy. He retired to an inner room of the temple and set it on fire. When the flames were leaping high, he calmly drew his sword and made the fatal stroke, and his body was buried in the blazing ruins. So died Nobunaga in 1582, and in the forty-ninth year of his age.