Battle of Hansan Island
The naval Battle of Hansan Island, also known as the Battle of Hansando, took place on July 8, 1592 near the Korean island of Hansan, and was one of the most important battles of the Imjin War. Korean admiral Yi Sun-sin destroyed at least 47 Japanese ships, capturing 12. Yi's success in this battle became a turning point in Hideyoshi's first campaign. This battle is also the first in Admiral Yi's 3rd Naval Campaign, and also is debated to be the third largest naval battle in world history, behind the Battle of Salamis and the Battle of Gravelines.
Prelude
Admiral Yi Sun Shin, along with the small fleet of seven ships of Admiral Won Gyun, had fought two campaigns across the southern coast of Korea. For the third campaign, Yi Eok-gi joined with Yi Sun-sin at Yeosu on August 10 before rendezvousing with Won Gyun at Noryang on August 12. In all, the Koreans sank over 60 Japanese ships. Admiral Yi and the combined Korean fleet did not lose any ships and suffered only 11 killed and 26 wounded up to this point.Given the importance that the Japanese navy had in supplying the army as it advanced along the Korean peninsula and prepared to invade China, Toyotomi Hideyoshi made it absolutely imperative to his commanders that the naval situation must be brought under control, the Korean fleets destroyed and the supply routes through the Yellow Sea secured. The Japanese commander, Wakizaka Yasuharu, was ordered to wait and combine his fleet with the forces of Katō Yoshiaki and Kuki Yoshitaka to seek out and destroy the Korean fleet. However, it would have taken some time for Katō and Kuki to assemble their ships, so Wakizaka went out alone with 73 ships. Wakizaka's fleet probably had the best warships fielded by the Japanese up to that point in the war. Out of the 73 ships, 36 were the large multi-decked atakebune, 24 the medium sized seki bune and 13 small kobaya scout ships.
In the meantime, Admiral Yi was planning a third campaign and worked with Admirals Won and Yi Eok Ki in combined operations and practiced arranging their fleets in a "crane's wing" battle formation. The formation was often used on land, but not normally used at sea. The combined fleets had a total of 54 panokseons and 2 or 3 turtle ships.
Battle
First phase
At Dangpo, Admiral Yi received intelligence from a local farmer that a large Japanese fleet was making its way west towards him and was anchored north of the Gyeonnaeryang Strait, a narrow channel between Geoje Island and the mainland.On August 14, the next morning, Admiral Yi sent out six panokseon battle ships through the channel to lure out Wakizaka's fleet. Wakizaka took the bait and his ships chased Yi's six panokseons through the channel and into the broad open sea in front of Hansan Island. Wakizaka saw Admiral Yi's fleet before him and pressed to engage the Koreans. At that time, Admiral Yi began to arrange the fleet in the crane wing formation.
Crane wing formation
In the two previous campaigns, the Koreans had either met the Japanese ships in a straight battle line or, if space was limited, with a circular or rolling method of attack, where their ships attacked in relays to sustain a continuous bombardment. Although these tactics were effective, considerable numbers of Japanese had escaped and swum ashore. The crane wing formation, also known as the hagikjin, was designed to not just sink ships, but to annihilate the enemy without losing a lot of men.The formation itself resembled a "U" shape, with the heaviest battleships in the center and lighter ships on the wings. There was a turtle ship at the end of each side, anchoring the flanks. Reserves were placed behind the central ships and would plug gaps as the formation expanded. Ships at the front of the formation would face broadsides to maximize the number of cannons that would be aimed at the enemy. Furthermore, the "U" shape itself would allow for interlocking fields of fire so that many Japanese ships would be enfiladed and hit from several angles. In this sense the Crane Wing formation shared similarities with the late-19th- and early-20th-century battleship tactic of 'Crossing the T'.
The Japanese tactic was to put their fastest ships in the vanguard to keep the Korean ships occupied, then move their larger ships rapidly to close in, grapple, and board the Korean ships. However, this tactic played right into Admiral Yi's plan, as the Japanese rowed deeper into the trap. The volume and range of Korean cannon fire prevented the Japanese from employing their favorite tactic and the two wings of the crane formation would envelop, surround and finally have the effect of "crowding in" the Japanese ships, making it difficult to maneuver or retreat and "packing" in the ships and present an easier target for Korean cannons.
Second phase
Wakizaka Yasuharu was a highly aggressive commander and one of the legendary "Seven Spears of Shizugatake," having gained fame in the battle that solidified Hideyoshi's claim to be Oda Nobunaga's successor. It is clear from his tactics in the Battle of Hansan Island that Wakizaka tried to get as close as possible to the Korean ships so he could have his men grapple and board them, which was a traditional Japanese naval tactic. Wakizaka not only followed the six decoy Korean ships through the Kyonnaeryang Strait with his entire fleet of 73 ships into the ambush, but pressed as quickly as possible into the center of the crane wing formation, oblivious to the fact that he was exposing his ships and his flanks to the Korean fleet's concentrated and longer-range firepower.The battle continued from the mid-morning to the late afternoon. Some boarding of Japanese ships by the Koreans did take place, but Admiral Yi only allowed it if the ship was already crippled and damaged. Wakisaka Yasuharu's Commanders Wakizaka Sabei and Watanabe Shichi'emon were killed. Commander Manabe Samanosuke committed seppuku aboard his burning, sinking ship. Wakizaka Yasuharu himself was hit by several arrows, but none penetrated his armor. After losing 59 ships, Wakizaka abandoned his flagship and boarded a faster, lighter ship. He managed to withdraw to Gimhae. In total, 14 Japanese ships were able to retreat from the immediate area of the battle. However, many of the surviving ships were damaged so badly that they had to be abandoned in some of the surrounding islands that dotted the southern Korean coast. Only a few ships ever made it back to the Japanese base at Pusan Harbor.
Aftermath
Admiral Yi's victory at Hansan Island effectively ended Hideyoshi's dreams of conquering Ming China, which was his original goal in invading Korea. The supply routes through the Yellow Sea had to be open in order for his troops to have enough supplies and reinforcements to invade China. Thus, Konishi Yukinaga, the commander of the contingent of troops in Pyongyang could not move further north due to lack of supplies, nor could more troops be sent to him because there was not enough food to feed them. It took five times the resources in food and men to move supplies via the land route over Korea's primitive roads. Furthermore, moving supplies overland left them vulnerable to attacks by regular Chinese and Korean forces as well as Korean irregular or guerrilla forces that were becoming increasingly active as the war progressed.After the battle of Hansan Island, Hideyoshi found it necessary to give a direct order to his naval commanders to cease all unnecessary naval operations and limit activity to the immediate area around Pusan Harbor. He told his commanders that he would come to Korea personally to lead the naval forces himself, but Hideyoshi was never able to carry through on this as his health was deteriorating rapidly.
The battle of Hansan Island was the most important battle of the Imjin War. It ensured that all the fighting would be in Korea, not China, and that Pyongyang would be the furthest northwestern advance of the Japanese armies. It can be argued that the battle was one of the most important in Korean history up to that point. While Hideyoshi was unlikely to be able to invade China and conquer a large part of it, the battle of Hansan Island checked his supply routes and hindered his movements in Korea. Hideyoshi's larger war plans, supported in much written documentation, was nearly identical to Imperial Japan's blueprint for conquest in the second half of the 20th century.