Who won the Battle of Jangjin Lake?
Battle of Chosin Reservoir
Roy E. Appleman, the author of US Army official history "South to Naktong, North to Yalu", writes that both sides could claim victory: the PVA 9th Army ultimately held the battlefield, while X Corps held off the Chinese 9th Army in a series of battles that enabled it to withdraw most of its forces as an effective tactical unit. Allan R. Millett qualifies a Chinese "geographic victory" that ejected X Corps from North Korea with the fact that the Chinese failed to achieve the objective of destroying the 1st Marine Division, adding that the campaign gave the UN confidence that it could withstand the superior numbers of the Chinese forces. The official Chinese history, published by PLA Academy of Military Science, states that despite the heavy casualties, the PVA 9th Army had earned its victory by successfully protecting the eastern flank of Chinese forces in Korea, while inflicting over 10,000 casualties to the UN forces.
Naval warfare
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 turtle ship (Geobukseon). Turtle ships 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.