structural:scholar_edition, information:classification
Military career

Yi Sŏng-gye started his career as a military officer in 1360, and would eventually rise up the ranks. In October 1361, he killed Pak Ŭi, who rebelled against the government. In the same year, when the Red Turbans had invaded and seized Gaegyeong (present-day Kaesŏng), he helped recapture the capital city with 3,000 men. In 1362, General Naghachu invaded Goryeo and Yi Sŏng-gye defeated him after being appointed as commander.

General Yi had gained prestige during the late 1370s and early 1380s by pushing Mongol remains off the peninsula and also by repelling the well-organized Japanese pirates in a series of successful engagements. In the wake of the rise of the Ming dynasty under Zhu Yuanzhang (the Hongwu Emperor), the royal court in Goryeo split into two competing factions: the camp led by General Yi (supporting the Ming) and the one led by General Choe (supporting the Yuan).

When a Ming messenger came to Goryeo in 1388 to demand the return of a significant portion of Goryeo's northern territory, Ch'oe Yŏng seized the opportunity and played upon the prevailing anti-Ming atmosphere to argue for the invasion of the Liaodong Peninsula (Goryeo claimed to be the successor of the ancient Korean kingdom of Goguryeo; as such, restoring Manchuria as part of Korean territory was a tenet of its foreign policy throughout its history).

A staunchly opposed Yi Sŏng-gye was chosen to lead the invasion; however, at Wihwa Island on the Amnok River, he made a momentous decision known as the Wihwado Retreat (위화도 회군; 威化島 回軍; lit. 'Turning back the army from Wihwa Island'), which would alter the course of Korean history. Aware of the support he enjoyed from both high-ranking officials and the general populace, he decided to revolt and return to Gaegyeong to secure control of the government.