During the end of the 16th century, Korea was invaded twice by Japan, first in 1592 and again in 1597. Japan failed both times due to Admiral Yi Sun-sin, Korea's revered naval genius, who lead the Korean Navy using advanced metal clad ships called turtle ships. Because the ships were armed with cannons, Admiral Yi's navy was able to demolish the Japanese invading fleets, destroying hundreds of ships in Japan's second invasion. During the 17th century, Korea was invaded again, this time by Manchurians, who would later take over China as the Qing Dynasty. In 1637, King Injo was forced to surrender to the Qing forces, and was ordered to send princesses as concubines to the Qing Prince Dorgon.