Kim's military campaign engaged the Jurchen clans such as the Odoli, Maolian and Udige capturing several castles, taking control of Hamgyong and continued pushing north expanding Korean territory to the Songhua River.

He also strengthened the administrative system to enable the government to determine exact population numbers and to mobilize troops effectively but caused Yi Si-ae's Rebellion.

The Qing forces purposely avoided battle with General Im Gyeong Eop, a prominent Joseon army commander who was guarding the Uiju Fortress at the time.

When a band of Dutch sailors, including Hendrick Hamel, drifted on Jeju Island, Hyojong ordered them to build muskets for the army, making it the first time to use firearms since the Imjin War.

After Hyojong died, Hyeonjong rose to the throne and continued his father's military expansion and reconstruction of the nation, devastated by the Seven-Year War and two Manchu invasions.

At its height, the rebellion controlled most of the area north of the Cheongcheon River, including the fortified town of Jeongju, to withstand invasions from Manchuria (part of the Qing Empire).

Some Korean officers being able, and others being men who had not devoted much time to the study of war, preferred archery, writing, practicing their calligraphy, and reading Confucian classics.

It allowed the higher military officers, the Jibyeonsa Jaesang (지변사재상; 知邊司宰相), to participate in the process of establishing security maneuvers to meticulously keep a keen eye on the issues of the border.

But, local officers could not individually respond to a foreign invasion outside their jurisdiction until a higher ranking general, appointed by the king's court, arrived with a newly mobilized army.

The Sogo Armies performed disastrously during the Manchu Invasions due to the county magistrates' poor management and outright corruption, who packed them with the old, weak, and infirm soldiers.

During Heonjong's reign, he reduced them to a corvée labor force, and their garrison commanders operated in the realms of public safety and pacification as thief-catching and tiger killing.

The Restriction Guard, also known as Geumgun in Korean, were a select group of highly trained soldiers who served as the personal bodyguards of the Joseon Dynasty's royal family.

The Restriction Guard played an important role in maintaining order and stability within the kingdom, and they were known for their loyalty to the royal family and their willingness to sacrifice their lives in defense of the throne.

The Geumguncheong was an important institution in the Joseon Dynasty, as the Restriction Guard played a critical role in maintaining the stability of the kingdom and protecting the royal family.

The unit was composed of soldiers who were selected from the common people rather than the aristocratic class, and it was intended to serve as a standing army that could be deployed quickly to defend the kingdom in times of crisis.

The soldiers in the Jangyongyeong Guard underwent rigorous training in martial arts, archery, and other combat skills, and they were equipped with modern firearms, such as muskets and rifles.

The spearmen were initially composed of highly skilled soldiers, but by the time of the establishment of the "Gyeongguk Daejeon" (경국대전), they were transformed into labor troops, including those employed in construction work.

[38] The armored soldiers (Gapsa (갑사)) are the palace guards and men-at-arms, the elite warriors of the central army who were a highly respected and privileged military unit.

[40] At the end of the period of chaos after the collapse of the Yuan Dynasty, Joseon was mainly focused on dealing with the looting of the Jurchen people and Japanese pirates in the north.

[41] The Five Guards was an important part of the social and political structure of the Joseon Dynasty, and it played a key role in maintaining public order and stability in the capital city of Hanyang, and its surrounding areas.

The Owi system was established in the 15th century during the reign of King Sejong, and it remained in place until after the Imjin War when the Joseon Army underwent significant reforms.

Each division consists of four brigades, each with about 2,000 gapsa constituting the core force among them and the Five Commands administers them through the General Headquarters (Owido), recruiting people from all provinces and the capital.

They were also responsible for protecting the royal palace, respond to emergencies such as fires and natural disasters, and serve as a reserve force for the main army and were called upon to participate in military campaigns when necessary.

It was also around this time that the military scholar Han Gyo (한교) wrote the martial arts manual Muyejebo, based on the book Jixiao Xinshu by the famous Chinese General Qi Jiguang.

[50] The establishment process of the Martial Arts Department is detailed in King Sunjo of Joseon's work called Pure Study Records (순제고).

The standard polearm used in the army was the jangchang (장창; 長槍), a four-meter spear wielded by infantry, and cavalry, for thrusting and drawing while moving forward and backward.

The infantry, but mostly cavalry, used the pyeongon, a 1.5 metres (4 ft 11 in)-long flail made from hardwood stick, painted red, acting as the handle for a chain attached to a shaft with iron nails.

[76] The se-chongtong, was a miniature gun held by its cheolheumja (철흠자, iron tong-handle), which allows a quick change of barrel for the next shot, and fires chase-jeon (차세전, a contemporary type of standardized arrow) with a maximum fatal range of 200 footsteps (≈250 meters).

Initially, Joseon considered the gun a failure due to its short effective range, but the chongtong quickly saw use after fielding to the frontier provinces starting in June 1437.

The Joseon Army began to adopt firearms during the late 16th century after Korean soldiers fought the Japanese and encountered the Portuguese and Dutch traders who had brought matchlock muskets to the region.