Although Yi Dynasty Korea had been beaten by the Japanese army, the Korean navy headed by Yi Sun-sin attacked, twice in May and June, actively fleet of ships that had been moving along the coast among troops at the rear of the Japanese army that had been expanding the area under its control based at Busan, and the Japanese fleet of ships that had not prepared for the damages suffered.
日本軍に大きく後れを取った李氏朝鮮であったが、釜山を基点として支配領域を広げていた日本軍後方部隊のうち、海岸移動を行っていた船団に対して李舜臣率いる朝鮮水軍が4月と5月の二回の出撃で積極的に攻撃を加え、備えのない日本船団は被害を受けた。