On 12 February 1793, Klenau received his promotion to lieutenant colonel in a Lancer regiment, and joined the Austrian force in the Rhineland, serving under General of Cavalry Count Dagobert Sigmund von Wurmser. He was captured later in the spring near the town of Offenbach, but was freed unexpectedly by two Austrian Hussars from the 17th Regiment "Archduke Alexander Leopold", who came upon him and his captors. At the first Battle of Wissembourg, Klenau commanded a brigade in Friedrich, Baron von Hotze's 3rd Column on 13 October 1793, during which the Habsburg force stormed the earthen ramparts held by the French.