The Imjin War and the rise of the Manchus were events of monumental importance in East Asian history. First of all, these were of immense continental scale. Toyotomi Hideyoshi’s (1536-1598) invasion of Korea, sometimes referred to as the First Korean War or the Great East Asian War, escalated into a six-year regional war in which the three East Asian countries, Japan, Korea, and China, fought either as allies or as enemies, each state directed by its head, with a commitment of large forces fighting on sea and land using firearms. In fact, this conflict involving more than 500,000 combatants over a course of six years was by far the largest war known to the world in the sixteenth century; in East Asian memory, it remained unequaled in scale until the Second World War. The Manchu incursion into Korea, which Hong Taiji (1592-1643) led with an army of 100,000, ended swiftly when the Korean court surrendered after a forty-nine-day siege of Namhan Fort, to which the Joseon [Chosŏn] court had fled. This was but one in a succession of victories that the Manchus achieved in the course of establishing their empire, which culminated with the conquest of Ming China (1368-1644) in 1644.
Both the Imjin War and the Manchu conquest brought fundamental domestic and regional impacts resulting in regime changes in Japan and China, respectively. Hideyoshi had brought all the domains of the Japanese archipelago under his control after a century and a half of fragmentation and “lawlessness.” After his death in 1598, which was in part responsible for the swift withdrawal of the Japanese troops from Korea, his successor was defeated by Tokugawa Ieyasu (1542-1616), who established the Tokugawa Shogunate (1603-1868) that presided over a peaceful and unified Japan until the Meiji Restoration of 1868. In China the Ming dynasty, an ethnic Han dynasty, was replaced by the Manchu Qing dynasty (1644-1911).
The Imjin War and the rise of the Manchu empire implied much more than the rise and fall of ruling houses; they also signaled realignments of power in East Asia and augured a new mapping, both conceptual and territorial, of the region. Hideyoshi invaded Korea as a first step toward constructing a great Asian empire that would include China and beyond. Though the Japanese Army never went beyond Korea, and Japan withdrew from Korea having accomplished none of its stated aims, the invasion announced the emergence of a new force and a new world vision manifest in Hideyoshi’s grandiose dream, short-lived though it was. The Manchu conquest of China, on the other hand, can be seen as the culmination of millennia of rivalry between “China” and a “barbarian” other, especially those whom the Chinese categorized as “northern” peoples, against whom the Great Wall had been repeatedly constructed through history. Their relation can be seen as an endless oscillation of aggression, retreat, conquest, and assimilation. That is, Chinese history is punctuated by periods of disunion during which some portion of China proper was occupied by some northern people or peoples, many of whom seem to have been assimilated into the Chinese cultural and ethnic community upon China’s reunification. The Mongol occupation of China appears to have diverged from the usual pattern. Yuan China (1271-1368) was one of four khanates with which Mongols ruled over half the world; after their hundred-year occupation ended, many left for their homeland. For the Manchus, the conquest of China was the fulfillment of a long-cherished dream, and by the time the Qing ended in 1911, very few Manchus seem to have reclaimed their ancestral ethnic origins. If the Qing conquest can be seen as the successful establishment of a multiethnic empire, the repercussions of this “barbarian” domination of China, the cultural heartland, reverberated through the region.
Historically, the later(17~mid 19th century) Korean army consisted of three main sectors; musket gunners or Po-su (literally means ‘gunner’), cavalries or Gi-byeong (literally means ‘cavalry’), and lastly artillery or Po-byeong ( literally means ‘artillery’). After two Manchu invasions of Joseon dynasty, the king and military generals needed a strong-new modeled army to fight back the Manchus and eventually, to disassemble united Manchurian tribes. Although the Manchurian Qing dynasty unified China and Korea remained their tributary state, this led to a series of military reforms in Korea. The old-fashioned melee spears and shield bearers, which they considered as great anti-cav unit, were absorbed into new Korean-styled tercio formations. The melee troops were placed in the front and flanks to protect the gunners, spears and gunners, which are the main bulk of the formation, were placed in the middle, and archers were placed in the rear to shoot down the enemy cavalries while the muskets are reloading. Following is the main doctrine of later-Joseon dynasty army. When the enemy formation approaches to engage in close combat, the artillery would harass the enemy formation and force them to either rout or break the formation and charge forward. The frontline of melee troops would absorb the impact of the charge, then the gunners and spears would shoot and thrust their weapons at enemies. When the enemies are finally repelled and are routing, the cavalries would charge forward and pursuit them. But the lack of professional melee infantries, obsolete artillery piece, corrupt government bureaucrats and many other reasons made the Korean army very weak, which led to Japanese occupation.
Joseon Korea also followed Confucian ideals and had a caste system. The population was divided into the yangban (scholarly aristocrats), sangmin (commoners) and cheonmin (lower class and slaves). The yangban held most of the wealth and took on government and military posts. The sangmin were labourers and were subject to conscription.
The Koreans had a long tradition of archery and made use of powerful composite reflex bows. A majority of the population practiced archery, especially the yangban and the sangmin who were aspiring to gain status. But a long period of peace degraded the military’s efficiency and it was considered as a mere rabble when the Japanese invaded in 1592. The best troops were the Northern Cavalry (horse archers) which defended the borders against the Jurchen. Much of the cavalry arm was destroyed by the Japanese during the battles of Chungju and Imjin River. The Sogo system was introduced in 1593 so that the Koreans could build a new professional standing army.
The Korean army was organized into battalions of mixed ranged and melee weapons. The most prominent missile weapon was the gakgung (composite reflex bow). Prior to the invasion, the Koreans did not bother adopting firearms because of the accuracy and speed of their bows. But bows proved to be inadequate against Japanese armour and tactics. They soon learned that the matchlock, though individually slow and inaccurate, could be quite devastating when fired en masse.
The Sogo reform recognised the importance of firearms. In close combat, the Joseon used a variety of polearms in the form of spears and tridents. These are classified as Heavy Weapon in the game.
Like the Chinese, the Koreans possessed several forms of artillery including the famous Hwacha rocket arrow launcher. Artillery was an important factor that contributed to the success of the Korean navy.
Korean soldiers were largely unarmoured except for the heavy mounted troops and generals, who wore brigandine armour.
During the Imjin War, resistance fighters called the uibyeong (righteous army) performed guerrilla raids and provided support during battles. They wielded various ranged and close combat weaponry and were sometimes thought to be better than the regular Joseon troops. Buddhist monks called the sungbyeong also joined the fight against the Japanese and gained a reputation for ferocity and bravery on the battlefield.