The Kobukson was not only impervious to almost any Japanese weapon, it was heavy and built for speed and could overtake anything afloat. The ship carried approximately forty 3-inch cannons that fired shot or steel headed darts, and had hundreds of small holes for firing arrows or throwing bombs. In comparison, the Japanese ships usually carried one cannon, many muskets, and no protective armor. The Kobukson was very effective in chasing down and sinking large numbers of Japanese troop and supply ships as well as successfully attacking numerous heavy Japanese battleships head on. It was the most highly developed warship of its time.
The Kobukson was constructed in a critical period in Korean history, one of the many times Korean and Japanese destinies converged.
First invasion in 1592 When Toyotomi Hideyoshi, the shogun of Japan, rose to power in 1590, he decided to control the internal feuding in Japan. Because Japan's largest threat was the other powerful war lords of Japan, he planned to tie up the financial resources of the lords with an invasion of China and thereby dilute their power. He requested that Korea aid him in his conquest. When it refused, he ordered two of his generals, Kato Kiyomasa (the Buddhist commander) and Konishi Yukinaga (the Christian commander), to attack Korea in April 1592.