Jeongyu War: Battle of Chilcheollyang: A Japanese fleet of 500 ships destroys Joseon commander Wŏn Kyun's fleet of 200 ships at Chilcheollyang.

The Imjin War was a series of two Japanese invasions of Korea: an initial invasion in 1592 also individually called the "Imjin War", a brief truce in 1596, and a second invasion in 1597 called the Chŏngyu War. The conflict ended in 1598 with the withdrawal of Japanese forces from the Korean Peninsula after a military stalemate in Korea's southern provinces.

The naval Battle of Chilcheollyang took place on the night of 28 August 1597. It resulted in the destruction of nearly the entire Korean fleet.

Joseon, officially Great Joseon, was a dynastic kingdom of Korea that existed for 505 years. It was founded by Taejo of Joseon in July 1392 and replaced by the Korean Empire in October 1897. The kingdom was founded after the overthrow of Goryeo in what is today the city of Kaesong. Early on, Korea was retitled and the capital was moved to modern-day Seoul. The kingdom's northernmost borders were expanded to the natural boundaries at the rivers of Amnok and Tuman through the subjugation of the Jurchens.

Wŏn Kyun was a Korean general and admiral during the Joseon period. He is best known for his campaigns against the Japanese during Hideyoshi's invasions of Korea. Wŏn was a member of Wonju Wŏn clan, which was well known for its members' military accomplishments. He was born in 1540 near Pyeongtaek and demonstrated his skill as warrior at a young age. He was qualified as a military officer and was first assigned to the northern border to defend against the Jurchens, who frequently raided Korean villages. Wŏn led many successful campaigns with Yi Il and Yi Sun-sin against the Jurchens. After considerable accomplishments on the northern frontier, he was promoted to admiral in 1592 and sent to the southern coast of Gyeongsang Province to command the province's Western Fleet, along with Yi Sun-sin, who became admiral before Wŏn and took command of Jeolla Province's Eastern Fleet. At the time, Wŏn and Yi were cavalry leaders who had no experience with naval warfare.