Knobelsdorff, originally a cavalry officer, had received awards in the Silesian Wars and was commander of the infantry regiments "Brunswick-Bevern" and "von Schwarz". In 1776 he was made Inhaber of the infantry regiment "Stojentin", stationed in Stendal. During the War of the Bavarian Succession he distinguished himself as brigade commander in the army of Prince Henry. In the campaign against Holland in 1787, he led the division on the left wing. The army commander at that time was the Ferdinand, Duke of Brunswick. At the outbreak of war against France in 1792, he remained in Stendal, while his regiment joined the corps of the Duke of Brunswick. However, when the war situation worsened and the Duke fell ill and had to leave the coalition forces in March 1793; Knobelsdorff took over as supreme commander of the Prussian troops. In the summer of 1793 Knobelsdorff was promoted to General of the Infantry and received special praise by the king. A frequent guest of the later, the old general was promoted to Generalfeldmarschall in 1798 and still participated in maneuvers at Potsdam in 1799.