In 1703, Münchow changed to the Prussian infantry regiment of the Prince of Hesse. With his promotion to the second lieutenant in 1707, he entered the regiment Markgraf Albrecht. During the Spanish War of Succession, he fought in the Prussian contingent on the imperial side in the battles of Malplaquet and Ramillies. Appointed staff captain in 1710, he participated in the Great Northern War at the Siege Stralsund. In September 1715 he became a captain with field command, and became a major in October 1717. In 1724, he commanded the Regiment Kalckstein. In May 1735 King Frederick William I promoted Münchow to colonel.