The great victory of Chi Lang - Xuong Giang (Lang Son - Bac Giang) and the Dong Quan oath -taking ceremony (Hanoi) were huge historic events 570 years ago (1427-1997). Two most important characters related to these events were the national heroes Le Loi and Nguyen Trai who were the head of the peasant revolution in Lam Son (Thanh Hoa) in the 15^th century against invaders from the North.