On March 26, in the Satsuma army with the reduced besieging army, KIRINO adopted an advice from the Kumamoto-tai troop and dammed up the Tsuboi-gawa River and Iseri-gawa River with stony embankments to flow the land surrounding the castle.
長囲軍が減少した薩軍は、桐野が熊本隊の建策を入れて、3月26日、石塘堰止を実行し、坪井川・井芹川の水を城の周囲に引き込んだ。