The naval Battle of Chilcheollyang took place before dawn on August 28, 1597 during the Imjin War in Chilcheollyang, which is a narrow strait near Geoje island.
The Battle of Chilcheollyang resulted in the destruction of the Korean navy and a huge loss of life.
When King Seonjo heard of the battle, he quickly pardoned Admiral Yi (who had spent some time as a common foot soldier under General Gwon Yul), and put him back as the commander of the now small and weak Korean fleet.
His battles, well documented in his diary and reports, bear careful study by modern naval historians, and his courage and patriotism are still models for modern Koreans of all persuasions, who find in him a powerful symbol of national resistance against foreign powers, particularly the Japanese.
Turtle Ships were first used in the Battle of Sacheon (1592) and were used in nearly every single battle until the devastating Battle of Chilchonryang, when every Turtle Ship was sunk; they did not re-appear in battle until the Battle of Noryang, which was the last naval battle of the war.
It was the kind of battle Admiral Yi had always won at, which was careful coordination of enemy movements and strategic moves, but Won Gyun allowed the Japanese to gain the upper hand and board the Korean ships and fight hand to hand combat, which was their primary strategy.