Yi Sun-sin
In Korea, the greater range of Korean cannons, along with the brilliant naval strategies of the Korean admiral Yi Sun-sin, were the main factors in the ultimate Japanese defeat. Yi Sun-sin is credited for improving the Geobukseon (turtle ship), which were used mostly to spearhead attacks. They were best used in tight areas and around islands rather than the open sea. Yi Sun-sin effectively cut off the possible Japanese supply line that would have run through the Yellow Sea to China, and severely weakened the Japanese strength and fighting morale in several heated engagements (many regard the critical Japanese defeat to be the Battle of Hansan Island). The Japanese faced diminishing hopes of further supplies due to repeated losses in naval battles in the hands of Yi Sun-sin. As the Japanese army was about to return to Japan, Yi Sun-sin decisively defeated a Japanese navy at the Battle of Noryang.