What this song renders
The Battle of Awazu is one of the better-attested engagements of the early Kamakura period. Yoshinaka, alienated from the imperial court and abandoned by most of his army, was caught at Awazu by his cousin Yoritomo’s forces under Minamoto no Noriyori and Yoshitsune. He had perhaps a few dozen riders left. The Heike, the Genpei Jōsuiki, and the Azuma Kagami all describe the day, with varying detail.
The Heike alone tells us that Tomoe was there. In its account, after the head of Uchida is taken, Yoshinaka turns to her and orders her to flee, saying it would be a lasting shame for him to die with a woman beside him. She protests, then obeys, and rides east. After this point in the narrative the Heike does not follow her.
Yoshinaka was killed shortly after. His horse stumbled into the half-frozen mud of a flooded ricefield; he was shot through the head by Miura Ishida no Tamehisa. Imai Kanehira, his milk-brother, killed himself moments later. The Kiso branch of the Minamoto ended at Awazu.
Yoshinaka’s death and the location of Awazu are well-documented across multiple sources. Tomoe’s presence and the order to flee are Heike-only. The chronological precision of the song — the cavalry gone, the horse in the shallows, the rider east — tracks the Heike’s sequence.