Prior to the battle, the previous naval commander Yi Sun-sin, had been removed from his post. The less experienced Won Gyun was promoted in Yi's place. Won Gyun set sail for Busan on 17 August with the entire fleet, some 200 ships.

The Korean fleet arrived near Busan on 20 August in 1597. As the day was about to end, they met a force of 500 to 1,000 Japanese ships arrayed against them. Won Gyun ordered a general attack on the enemy armada, but the Japanese fell back, letting the Koreans pursue. After a few back and forth exchanges, with one chasing the other, one retreating, the Japanese turned around one last time, destroying 30 ships and scattering the Korean fleet. His ships were overwhelmed by arquebus fire and the traditional Japanese boarding attacks, which largely resulted in the destruction of his entire fleet. Bae Seol shifted 12 ships to an inlet farther down the strait and managed to escape.