This paper examines how the Buddhist Vietnam became Confucian-dominated since 1400, when the Buddhist Tran dynasty was succeeded by the Le dynasty. Through a series of Mongol invasion in between 1250s and 1280s, the civilian-led military, which was the main resistance force, started spreading its political power and Confucian influence over the country. In the 1380s, Ho Quy Ly's political ambition to be the successor to the throne led him to emphasize early Confucianism, further leading the Vietnamese society away from Buddhism. The next turning point came in 1407 when the Ming Dynasty invaded Vietnam and started enforcing its 20-years of neo-Confucian assimilation policy to transform the Vietnamese culture, although the policy did not have a substantial effect on the country. In 1428, Le Loi took power in the Eastern Capital and renamed the country as Dai Viet. This event meant more than a simple change of dynasties. It meant the country had officially become Confucian. When Le Thai-to was succeeded by young Thai-tong and Nhan-tong, conflicts between the older officials from the Thanh-hoa group and the younger Tongking delta scholars hindered consistent promotion of Confucianism as the ruling ideology. It was Le Thanh-tong who later consolidated the Confucian culture in Vietnam. Following the Confucian teaching, he emphasized loyalty and strengthened his imperial power.