In a brilliant military move, Admiral Yi took the entire Korean Navy, 180 small and large ships into the Japanese homeport at Pusan harbor and attacked the main Japanese naval force of more than 500 ships that was still at anchor. Using fireboats and strategic maneuvering, he sank over half of the Japanese vessels. However, receiving no land support, Admiral Yi was forced to withdraw. With this battle, Admiral Yi completed what some naval historians have called the most important series of engagements in the history of the world.
During one patrol sweep, Admiral Yi's fleet spotted 26 Japanese ships on the horizon. He spread out his forces in a formation known as the fishnet and advanced. The fishnet or inverted V grouped the heaviest ships of the fleet at its vortex. As the enemy ships were forced inside the V, they were trapped and destroyed by Yi's heavy ships.
Korean control of the sea, under the command of Admiral Yi Sun-Sin, soon forced the Japanese invasion to a complete standstill. Although the Japanese ground commanders begged for supplies, neither supplies nor reinforcements could get past Admiral Yi Sun-Sin to reach the Japanese forces along the western coast of the peninsula. Because of this situation, the following months saw little military action.