When Yoritomo left Awa, moved up the Boso Peninsula, and reached Sumidagawa River with the Chiba clan, Hirotsune met them with a large army of 20,000 horse soldiers.
頼朝が安房を発し、房総半島を北上し、千葉氏らを加えて隅田川に達したとき、広常は2万騎の大軍を率いて参じた。