Shortly before the beginning of the War of Austrian Succession (1740–1748), the new king, Frederick, sent Moulin to Vienna explore the situation with Austria. Consequently, he was not with the troops at the outbreak of war, but returned to the Prussian army to take part in the Battle of Mollwitz on 10 April 1741. He was promoted to major general on 5 June, and on 25 June he became the proprietor of the Infantry Regiment Nr. 37, garrisoned in Breslau. The previous proprietor was Paul Heinrich Tilio de Camas. In 1742, Moulin covered the rear of the army during the Battle of Chotusitz and then became commander-in-chief of the fortress at Glogau. In gratitude for his services, he received the municipal office of Raden at Rinteln, in addition to that of Kolbatz, which he had held since 1731.