The Ming army headed by the accountant Yang Hao and admiral Ma Gui attacked the nearly complete Ulsan Japanese Castle in early February 1598 (the First Battle of Ulsan) against the Japanese army, which was expanding its domain and building winter quarters, and when Kiyomasa KATO struggled against the Ming army the Japanese army based in the west formed reinforcements for Ulsan and defeated the Ming army.
占領地を広げて冬営のために布陣していた日本軍に対し、12月末から経理楊鎬・提督麻貴率いる明軍が完成間近の蔚山倭城へ攻勢をかけ（第一次蔚山城の戦い）、加藤清正が苦戦すると西部に布陣していた日本軍は蔚山救援軍を編成して明軍を撃破した。