Those were unforgettable memories for doctor Nguyen Thai Long and his comrades from Regiment 567 - Regiment Phu Hoa - Khau Chia, about twelve days and nights of smoke and fire on Khau Chia pass, nearly a month of fighting on the Cao Bang front and for many years fought for every inch of land in Vi Xuyen, Ha Giang. Memories of the war years come back, reminding today's generations of the sacred war to protect the northern border of the Motherland since that spring of 1979.