Azuma Kagami: On the 20th day of the 10th month, Yoritomo reached Kashima in Suruga, and Taira no Koremori, Tadanori, and Tomonori camped on the west…
On the 20th day of the 10th month, Yoritomo reached Kashima in Suruga, and Taira no Koremori, Tadanori, and Tomonori camped on the west bank of the Fuji River. In the middle of the night Takeda Nobuyoshi tried to attack the rear of the Taira camp in secret, but the waterfowl on the Fuji marsh rose all at once, and the beating of their wings sounded like an army, startling the Taira. Tadakiyo, saying that all the eastern forces had gone over to Yoritomo, hurried back before dawn.
陣于富士河西岸。
Location: 吾妻鏡 卷1 治承四年10月20日条 (zh_吾妻鏡_卷001.wiki 292행)
Taira no Koremori's army advanced to the Fuji River but, startled at night by the sound of waterfowl, men and horses trampled one another and fled back west.
進軍于富士河。
Location: part_01 L125
Fujigawa: the Taira western army, startled at night by the sound of waterfowl taking flight, collapsed and fled.
鵝鴨驚起。西軍大駭潰走。
Location: 卷之二 L156