In the fifth month of 1183, a great Taira army of over a hundred thousand riders under Taira no Koremori camped on Mount Tonami, on the border of Kaga and Etchu, to strike Kiso Yoshinaka, who had raised an army in the Hokuriku region.
Yoshinaka had only some fifty thousand. In a straight fight he had no chance. He thought, "The Taira are many, so they will surely try to cross the mountains to open ground and push with force. Before that, I'll lure them into the mountains and drive them over the cliffs."
During the day, Yoshinaka deliberately started skirmishes to buy time, and set up white banners in rows to make the Minamoto look numerous. The Taira thought, "A great Minamoto army is waiting. Let us rest the horses at Kurikara Pass in the mountains," and camped at the pass.
When night came, Yoshinaka's forces circled behind the Taira and to either side, and raised a war cry all at once from every direction. The Taira soldiers panicked in the dark, looked for a way to escape, and tumbled like an avalanche into the valley of Kurikara.
When a father fell, his son fell too; when an elder brother fell, the younger followed. Men lay on horses and horses on men, and that deep valley was filled with over seventy thousand Taira riders. Spring water flowing from the rocks at the bottom became a river of blood. People called this valley "Hell Valley."
The later Genpei Seisuiki tells of the "fire-ox stratagem," in which Yoshinaka tied torches to the horns of hundreds of oxen and drove them into the Taira camp. Victorious at Kurikara Pass, Yoshinaka pressed on to the capital, and the Taira abandoned it and fled to the western provinces.