Yi Sun-sin and Won Gyun arrived near Okpo on 16 June and a scouting vessel alerted them to the presence of Japanese ships anchored there.
Yi Sun-sin's fleet approached Okpo on 17 June. They formed battle positions with the heavy warships in the center and light vessels to the left and right. When they entered the harbor they found more than 50 transport ships, mostly unmanned, and the Japanese looting in the village. The Japanese didn't notice them until it was too late due to smoke around Okpo and panicked. Some fled into the hills whiles others tried to flee aboard their ships, but those that did were surrounded and hemmed into the port. The Japanese tried to fight back with their firearms but did little damage to the battleships. Yi Sun-sin proceeded to bombard them until they abandoned ship. In total 26 transports were destroyed during the bombardment. The Koreans suffered three injuries, and two of them were from friendly fire. When a group of Yi Sun-sin's men seized a Japanese ship, Won Gyun's ships fired on them, mistaking them for enemies.
After the battle Yi Sun-sin immediately received news of five other Japanese ships within their vicinity and gave chase. The Japanese fled to Happo harbor and abandoned their ships.
The next day they received news of another 13 Japanese ships nearby and found them at Jeokjinpo. The Japanese fled inland while their ships were looted and then burned.
When they received news of the fall of Hanseong, Yi Sun-sin and Won Gyun parted ways and returned to their home ports. Yi Sun-sin arrived back at Yeosu on 18 June.
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