When General Kim informed the king of Admiral Yi Sun Sin's refusal to go, Admiral Yi's enemies at court insisted on his replacement by Won Kyun and his arrest. As a result, in 1597 Admiral Yi Sun-Sin was relieved of command, placed under arrest, taken to Seoul in chains, beaten, and tortured. The king wanted to have Admiral Yi killed but the admiral's supporters at court convinced the king to spare him due to his past service record. Spared the death penalty, Admiral Yi was demoted to the rank of common foot soldier. Yi Sun-Sin responded to this humiliation as a most obedient subject, going quietly about his work as if his rank and orders were totally appropriate.
With Admiral Yi stripped of any influence, when negotiations broke down in 1596, Hideyoshi again ordered his army to attack Korea. The invasion came in the first month of 1597 with a Japanese force of 140,000 men transported to Korea in thousands of ships. Had Admiral Yi been in command of the Korean Navy at that time, the Japanese would most likely never have landed on any shore again. Instead, the Japanese fleet landed safely at Sosang Harbor.
The spy Yosira continued to urge General Kim to send the Korean Navy to intercept a fleet of Japanese ships. When ordered to do so, Won Kyun gathered his 80 ships together and reluctantly set sail. This fleet was hardly recognizable as Yi Sun-Sin's former one. Won Kyun had eliminated all of the rules and regulations set up by Yi when he took command as well as purging the ranks of all who had been close to Admiral Yi. His inept maneuvers almost destroyed the entire Korean fleet and alienated all his men. Consequently, this battle ended in a complete defeat for the Korean Navy, while Yi Sun-Sin was being detained as a foot soldier.