Late Goryeo Military Reforms

Timeline

1. c. 1388–1389Southeastern coast of the Korean Peninsula · Korean PeninsulaIn the late 14th century, wokou frequently raided Goryeo's southeastern coast; the court was forced to strengthen the navy and coastal garrisons, and the military faction grew in power through military merit, loosening the military-political structure.
2. 1388Wihwa Island · North Pyongan ProvinceLi Chenggui (Yi Sŏng-gye) was ordered to lead a northern expedition into Liaodong but turned his forces back at Wihwa Island, refusing to cross the river to attack Ming; this became the key turning point in the military faction's seizure of power, shifting frontier strategy from a pro-Yuan northern expedition to pragmatic self-defense.
3. 1392Kaesŏng · GoryeoIn 1392, Yi Sŏng-gye deposed the last Goryeo king and established himself as ruler, changed the state name to Joseon, moved the capital to Hanyang, and began reorganizing the army and rebuilding the military-administrative system along Ming lines, marking the institutional culmination of the late Goryeo military reforms.
4. 1393–1400Hanyang · Joseon dynastyAfter the Joseon dynasty was founded, it submitted to the Ming dynasty, adjusted northern frontier defenses and garrisons along the Yalu River line, disciplined the military faction, and introduced Ming firearms and wei-so-style garrison defense concepts, completing the late 14th-century military transformation.