Ordered to invade Manchuria, General Yi turned his army around instead
In 1388 General Yi Songgye led an army north to attack Ming-held Liaodong, a campaign he had opposed. At Wihwa Island on the Amnok River he halted, turned back and marched on his own capital. Four years later he ended the 474-year-old Goryeo dynasty and founded Joseon, which would rule Korea for five centuries.
Yi was born on 4 November 1335 in Ssangseong Prefecture, a frontier district of the Mongol Yuan empire, where his father, Yi Chach'un, was an ethnic Korean official in Yuan service. In 1356 the family switched allegiance to Goryeo and helped it seize the prefecture from its governor.
Goryeo, founded in 918, was by then badly weakened by war and Mongol domination, its royal line tangled by forced marriages into the Yuan imperial family, and even King U's parentage was questioned because his mother was known to be a slave. Japanese pirates and the Red Turbans raided repeatedly. Yi joined the army in 1360 and made his name defending the realm: he helped retake the capital Gaegyeong from the Red Turbans with 3,000 men, beat the invading general Naghachu in 1362, and later drove Mongol remnants off the peninsula and repelled pirate fleets. At court he led the faction favouring the rising Ming dynasty, against his rival Ch'oe Yong, who backed the Yuan.
When a Ming envoy demanded a large slice of Goryeo's northern territory in 1388, Ch'oe pushed for war. After the retreat from Wihwa Island, Yi's army entered the capital and defeated the loyalists, and Ch'oe was eliminated. Yi deposed King U but did not take the throne, installing U's eight-year-old son and then, after a failed restoration attempt, having both killed. A distant royal relative became a puppet king while Yi allied with reforming scholar-officials such as Chong Tojon and Cho Chun.
He finally took the crown himself in 1392. As king he favoured continuity: he created no new institutions and carried out no mass purges, leaving the same families and officials largely in charge, while restoring friendly ties with Japan and improving relations with Ming China. Strife among his sons pushed him to abdicate after just six years. He died on 27 June 1408, and centuries later the Korean Empire honoured him as Emperor Ko.
Source: Taejo of Joseon
