Sacheon brought the turtle ship into combat

The Japanese squadron at Sacheon sat beneath positions from which massed arquebus fire could punish a direct harbor attack. Yi personally reconnoitered the area, sent panokseon forward as a lure, and concealed the turtle ship until the Japanese followed the apparent retreat into open water. The Korean force then reversed course and attacked with cannon and fire arrows; the covered turtle ship could drive through the enemy without offering an easy boarding target. Yi suffered a minor arm wound, but the Japanese warships were destroyed and the action validated further turtle-ship construction.