The Battle of Busan of 1592 (or more accurately, the Battle of Busanpo or Battle of Busan Bay) (釜山浦 海戰) was a naval bombardment of anchored Japanese ships at Busan. Yi Sun-sin managed to destroy over 100 Japanese ships and retreated with minimal casualties.
It was a naval engagement that took place on 01 September 1592 during the first phase of the Japanese invasions of Korea. It was a Korean surprise attack on the fleet of Toyotomi Hideyoshi stationed at Busan, and its main objective was to recapture Busan, which would thoroughly cutoff the supply line of the Japanese army. In this battle, officer Woon(ko) and six soldiers died, and the Japanese lost over 100 ships, but the control of Busan was maintained under the Japanese forces as well as the control of the sea from Japan to Busan. The occupation of Busan by the Japanese forces was kept until November 1597, when the retreat of the Japanese forces was finished due to the death of Hideyoshi.
After commander Yi Sun Shin’s fleet decisively defeated the Japanese in the Battle of Hansan on 08 July, the Japanese had to change their war strategy. Their strategy was to deliver more land forces and supplies by sea to the northern part of the Korean peninsula and then they would march into Ming China. With the failure of this strategy, Japanese troops in the northern provinces of Joseon Korea had to suffer from starvation and shortages of supplies. To invade China, they needed to secure war supply routes. The alternate plan was to advance troops and supplies by roads, but this route was blocked by the Uibyeong (“Righteous Army”). Many Korean civilians and Buddhist monks formed a voluntary army and attacked Japanese troops.
Formation of United Joseon fleet
After the Battle of Hansan Island, in which commander Yi Sun-sin’s navy won against the Japanese navy around mid-July, they remained silent for nearly a month. In mid-August Japanese Kato Yoshiaki’s army, Kimura’s army, and Okamoto’s army retreated from Hanyang, the later capital of the Joseon dynasty, to Gyeongsang Province. Around this time, most of the Japanese troops retreated to Gimhae to secure their munitions. In addition, following the Battle of Hansan Island, the Japanese navy retreated to Busan and focused on protecting and rebuilding their positions. Commander Yi sent spy ships to Busan port and found out there were about 470 warships there. Commander Yi believed that the Japanese were retreating to their country, so Gyeongsang Province Governor (慶尙右水營) Kim Soo requested that Commander Yi block their sea route. Therefore, Commander Yi with Commanders Won Gyun and Yi Eok Ki united their fleets, for a total of 166 vessels. On their way to Busan, Commander Yi defeated 24 Japanese ships at Seopyeongpo (西平浦), at the Battle of Dadaejin (多大浦), and at Jeolyoungdo (絶影島). The combined Joseon fleet defeated the Japanese navy repeatedly, largely as a result of their well-trained sailors and the Joseon ships’ medium- and long-range cannons.
Battle of Busanpo
Off the coast of Busan, the united Joseon fleet realised that the Japanese navy had readied their ships for battle and the Japanese army had stationed themselves around the shoreline. The united Joseon fleet assembled in the Jangsajin (長蛇陣), or “Long Snake” formation, with many ships advancing in a line, and attacked straight into the Japanese fleet. Overwhelmed by the Joseon fleet, the Japanese navy abandoned their ships and fled to the coast where their army was stationed. The Japanese army and navy joined their forces and attacked the Joseon fleet from the nearby hills in desperation. The Joseon fleet shot arrows from their ships to defend and restrict their attacks, and in the meantime concentrated their cannon fire on destroying Japanese vessels. The Korean ships fired on the Japanese fleet and burned them using fire arrows while the Japanese fired on them from above in their forts. Even with cannons captured at Busan, the Japanese did little damage to the Korean warships. By the time the day had ended, 128 Japanese ships had been destroyed. Yi Sunsin gave orders to withdraw, ending the battle.
In terms of size, the Joseon ships were one-third that of Japanese ships. Although commander Yi destroyed over 100 ships, he did not order his soldiers to pursue the Japanese on shore, probably because he recognised that close hand-to-hand combat skills of the Joseon were significantly weaker than those of the samurai. In addition, the Joseon soldiers were exhausted from long sea travel and battle, and would have been heavily outnumbered on land. Up to that point, Commander Yi had not fought with numbers of soldiers, but rather with ships and cannons. Yi reinforced disadvantages in number of soldiers with heavy use of firearms. The Japanese also had a well-trained cavalry, which was another aspect the Joseon army lacked. Instead of the Joseon fleet, Yi lost one of his cherished officers, by the name of Woon.
Yi Sun Shin originally intended to destroy all the remaining Japanese ships, however, he realised that doing so would effectively trap the Japanese soldiers on the Korean Peninsula, where they would travel inland and slaughter the natives. Therefore, Yi left a small number of Japanese ships unharmed and withdrew his navy to resupply. And just as Yi suspected, under the cover of darkness, the remaining Japanese soldiers boarded their remaining ships and retreated.
After this battle, the Joseon naval activity substantially subsided. Before then, there were 9 naval battles during 3 months since May 1592, which were led by Yi, but the next naval battle took place 6 months later in February 1593. The Japanese forces succeeded to protect their position in Busan bay as well as the supply line from Japan. Since the Japanese forces realised the importance of defence lines of Busan bay to secure the supply line, they tried to bring the west area of Busan under their control, where the Joseon navy came. This attempt led to the Battle of Jinju in October 1592, in which General Kim Si-min triumphed over 20,000 Japanese troops, and Battle of Jinju in June 1593, in which Japanese forces finally captured the castle in Jinju.