Infantry was the largest branch and the backbone of the Nguyen army in the first half of the nineteenth century, yet under the reign of Minh Mang, it has so far been treated only incidentally within general studies of the army. Drawing directly on the Dai Nam thuc luc and the Minh Menh chinh yeu, cross-checked against the Kham dinh Dai Nam hoi dien su le, published Vermilion Records, and Vietnamese and foreign scholarship, and employing historical and logical methods together with quantitative, comparative, and source-critical analysis, this article reconstructs the Nguyen infantry between 1820 and 1840 along three dimensions: the institutional premises of force building; organisational structure, establishment, and troop strength; and the regimes of recruitment, rotation, and remuneration. The findings show that, through the reforms of 1826, 1829, and 1831-1832, the infantry was brought into a uniform doanh - ve - doi - thap - ngu establishment and a centralised chain of command; its registered strength at the end of the reign was roughly 120,000 men, about four-fifths of the total army as classified in the Hoi dien, although the number actually on duty was considerably lower because of the rotation system; recruitment, rotation, pay, uniforms, death benefits, and the discharge of disabled soldiers were all codified into standing regulations. The gap between the prescribed establishment and actual practice is identified as the basic limitation of this model.