One of the most heroic chapters in our nation's history is the liberation of the South and the reunification of the country in the 20th century. Miraculously, we can witness this through letters, handwritten and typewritten ones, from General Secretary Le Duan to commanders and leaders in the South. These letters conveyed top-secret orders, supreme directives, political viewpoints, theoretical discussions, and even combat tactics. They were also imbued with the camaraderie of comrades-in-arms, the solidarity of compatriots, and the heartfelt sentiments of a son of Vietnam. These letters were later compiled into the anthology “Thu vao Nam” (Letters to the South), bearing unique and exceptional value for future generations.