On July 12, having appointed his brother Masazumi as a magistrate and established the checkpoint at Echigawa, Omi, Mitsunari prevented the saikoku daimyo (feudal lords in countries west of the Kinki district) such as Katsushige NABESHIMA and Shigekatsu MAEDA from going on an expedition to Aizu under Ieyasu's command, and forcibly moved them over to his side (the western army).
7月12日、兄・正澄を奉行として近江愛知川に関所を設置し、家康に従って会津征伐に向かう後発の西国大名、鍋島勝茂や前田茂勝らの東下を阻止し、強引に自陣営（西軍）に与させた。