On April 3, the Satsuma army raided the detached 3rd brigade under the cover of fog in the early morning, but the brigade drove back the Satsuma army after a five-hour fierce battle, chased it across the Midori-kawa River, attacked the back side and the flank of the Satsuma army, and seized Kosa after further advancement.
3日、早朝の霧に乗じた薩軍の急襲を別働第3旅団は激闘5時間の末、これを退け、追撃して緑川を越えて薩軍の側背を衝き、進んで甲佐を占領した。