The Republic of Korea Navy was founded on November 11, 1945 as Marine Defense Group after Korea was liberated from the Empire of Japan. The ROK Navy is the oldest service within the ROK Armed Forces. In 2015, the South Korean navy celebrated its 70th anniversary. Since the Korean War, the ROK Navy had concentrated its efforts on building naval forces against the North Korean navy, which has littoral naval capabilities. As South Korea's economy grew, the ROK Navy was able to locally build larger and better equipped fleets to deter aggression, to protect the sea lines of communication, and to support the nation's foreign policy. As part of its mission, the ROK Navy has engaged in several peacekeeping operations since the turn of the 21st century. The ROK Navy aims to become a blue-water navy in the 2020s. Origins Korea has a long history of naval activities. In the late 4th century during the Three Kingdoms Period, Goguryeo defeated Baekjae by operating amphibious forces of 40,000 men. In 732, the Balhae navy "attacked the Shandong peninsula and destroyed the biggest seaport of the Tang Empire in the east – Dengzhou." In the 9th century, Commissioner Chang Bo-go of the Unified Silla established a maritime base called Cheonghaejin in an island to foster trading with China and Japan, and to eradicate pirates. In 1380, the naval forces of the Goryeo Dynasty defeated 500 vessels of invading Japanese pirates by deploying shipboard guns, devised by Choi Moosun, which is claimed to be the first use of shipboard guns in the naval history. In 1389 and 1419, the Korean naval force invaded Tsushima Island to suppress the Japanese pirate. In the early years of the Joseon Dynasty, the naval forces once reached its peak of 50,000 personnel due to the pirate issue. During the Japanese invasions of Korea (the Imjin War) in the 16th century, the Korean naval force commanded by Admiral Yi Sunshin, who later became the head of the Navy (Commander-in-Chief, Three-Provincial Fleet), cut off the invaders' naval life line and defeated the Japanese fleet reversing the war in favor of Joseon. Comparing Yi Sunshin to Lord Nelson, Admiral George Alexander Ballard of the Royal Navy commented: "It is always difficult for Englishmen to admit that Nelson ever had an equal in his profession, but if any man is entitled to be so regarded, it should be this great naval