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Korean Military Evolution and Tactics in the 16th and 17th century

When we look back at the Korean military back in the 16th and 17th centuries, we are often given general information about it and on its actions during wars that occurred throughout this time period. From the Imjin War to the later Qing invasions decades later, we are shown the Korean military in a manner that makes one think of them as weak, ill-prepared and not very effective as a fighting force. Chosŏn’s military failures during the first Japanese invasions of Korea during the Imjin War or the Qing invasions of Korea in 1636 are often used as examples of the ineffectiveness of the Korean military. Take for example, what the Chosŏn military official named Shi-eon Lee, said about the soldiers in the Korean army, “The Korean soldiers cower before the enemy and flee for their lives even before they have engaged the enemy. As for the commanders, they seldom leave their positions because they fear that they may be executed for deserting,” (The Annals of the Chosŏn Dynasty). Now, as many may know, the Japanese invasions of Korea were devastating, hundreds of thousands lost their lives, and the Korean military was truly unprepared for the invasion by the Japanese. However, it is not true that the Korean military remained this way after the initial invasion. It is here that I would like to introduce my topic and the purpose of this essay. I will discuss the Korean military during the sixteenth and seventeenth centuries. I will focus on how the Korean military adapted to new modes of war, which new technologies they were introduced to, how they adapted tactics and how effective and important these changes were for the military.

To start things off, I wanted to mention something rather important about Chosŏn’s military at the start of the Imjin War which explains why they were rather ineffective in stopping a Japanese invasion. Prior to the Imjin War, Chosŏn did not rely on a professional standing army. This doesn’t mean that Chosŏn had no troops at all or that the country was completely undefended when under attack, but it did mean that the majority of Korea’s soldiers were ill-trained conscripts who would not fare very well against a hardened army like that of the Japanese and their superior weaponry, in particular the arquebus, or musket, an early kind of firearm. This weapon was vital not only to the Japanese in their invasion of Korea but also for the Koreans who were defending their land during the Imjin War and many years to follow, due to its usefulness and capabilities in combat. According to Kang Hyeok, “The Japanese troops swept through Korean defenses with their capable musketeers and captured the capital within three weeks.” (Kang, 138) These musketeers were therefore very effective weapons in capable hands.

So, how did Chosŏn respond to the lessons learned from the Imjin War? One important lesson learned was that Korea needed a professional standing army in case something like this happened again; a conscript army raised quickly to defend the country in times of war was no longer viable. In 1593, a year after the outbreak of the Imjin War, King Sŏnjo issued a series of emergency decrees to institute the Military Training Agency (MTA, Hullyŏng togam ), a new institution designed specifically to train musketeers. The first professional standing army established in Chosŏn, it employed salaried soldiers that “benefited from government surtax.” (Kang, 140) What made this army stand out even more, beyond its usage of these new weapons, muskets, for the majority of its troops, was how recruits and soldiers made up it’s ranks. As Kang describes it, “men from all walks of life were recruited for new musketeer divisions, starting with 500 in 1593 and increasing to 2000 by the end of the war. 4000 by 1616 and 6350 by 1658.” (Kang, 140) Seeing how the musket was a rather simple weapon to master, it was much easier to train an army of men to use these firearms than it would be to train them in more traditional weapons such as swords, spears, and bows.

Why was the musket so important for the Korean army, its “modernization?” What changes in tactics did these weapons introduce? For starters, musket warfare was not something native to Korea. It was of foreign origin and required Chosŏn soldiers to learn new skills to suit the needs of it’s military. Under Yu Sŏngnyong who was Chief State Councilor of Chosŏn during the Imjin War, Korea quickly adapted to the global trends of firearms warfare and started a process of military reform which saw Chosŏn center its army around firearms and professional soldiers. As firearms became the core or the Korean military, soldiers bearing firearms began filling up more and more ranks of the army. In 1594, Only a year after the Imjin War began, musketeers made up 54% of the Military Training Agency and quickly replaced more traditional units such as bows and cavalry.  By 1682, musketeers made up 80% of Chosŏn’s military force and completely replaced all archers, and by 1708, there were as many as 4000 musketeers within the army’s ranks. In regard to tactics with firearms, Chosŏn largely “forged their own methods of firearms tactics based on the Chinese General Qi Jiguang’s “Three-Unit-Technique” a mutually supportive infantry regime featuring three distinct types of infantry: The musketeer (p’osu), the archer (sasu) and the swordsman/spearman (salsu; literally meaning the “Killing Unit”).” (Kang, 141) Qi’s military manuals were “Fine Tuned” by Korean officers and in the Korean version of Qi’s manuals, the musketeers played a more central role. “As laid out in the Orientation to the Military Arts, Korean musketeers fought at the forefront of the battle and served as the tactical axis around which other units revolved to provide protection.” (Kang, 142)

As many people may already be aware, muskets while being very powerful, fired very slowly with many of the best muskets from later periods in time only being able to fire about 4 to 5 rounds per minute.  With this in mind, we know why musketeers had to work in tandem with other military units as they were vulnerable after firing their guns and having to reload. While muskets did eventually phase out archers and swordsmen/spearmen, for some time, these units were required for the musket to be used to their full effect as they safeguarded musketeers from enemy encroachment. Like their counterparts in Europe, Koreans used Linear formations which featured “layers of soldiers advancing and receding in flexible ways, allowing musketeers to fire and other units to provide cover at appropriate times.” (Kang, 142) Special drills were conducted in regard to specific conditions that may have surfaced on the battlefield, say for example a cavalry charge. In this situation the soldiers needed to divide into sequential lines and wait for their turn to fire, in the meantime tamping their barrels, pouring in the necessary gunpowder and while attempting to light a match. Stressful situations such as those on the battlefield demanded strict discipline from soldiers and turned them into “a synchronized unit that could keep together in time.” (Kang, 142) As time passed and the Korean military continued to evolve, tactics in turn continued to change as well. For example, in 1636 the scholar Chŏng On devised a new formation called the “Three Layer Formation” in which musketeers and archers would shoot in volleys. “By 1649 more elaborate descriptions were made in military manuals along with diagrams and the like.” (Kang, 143)

From these examples and information recorded since the introduction of firearms in the Chosŏn army we are able to see how much of a role, firearms (or muskets to be exact), had in the evolution of Korea’s military. From a weapon that caused havoc in the hands of the Japanese and which was feared by King Sŏnjo during the Imjin War, it became a cornerstone of the Chosŏn army in less than two centuries. I found it fascinating how quickly the Korean army not only formed as a professional force, but also adapted the tactics and technology from their neighbors, in some cases improving them to better suit their needs. I feel like this should be a reminder that Chosŏn’s military was not as obsolete or weak as many people may have believed it to be during the Imjin War or the Qing Invasions of the early 1600’s. The Korean military, just like any other military force, learned from their mistakes, improved on what they lacked and adapted to the changing times just as the army of any other nation would do in tandem. The Chosŏn army may not have been as well recognized as those of Toyotomi Hideyoshi or of the Ming Chinese, but they existed, adapted and improved when it was necessary.



Omar Sanchez (Japanese, UCLA '22), “Korean Military Evolution and Tactics in the 16th and 17th century,” UCLA Korean History and Culture Digital Museum, accessed July 18, 2024,