In 1796, Klenau commanded the advance guard of Peter Quasdanovich's right column in northern Italy. As the column descended from the Alps at the city of Brescia, reconnaissance found the local French garrison unprepared. At midnight, Klenau led two squadrons of the 8th Hussar Regiment "Wurmser" (named for its Colonel-Proprietor Dagobert von Wurmser), a battalion of the 37th Infantry Regiment "De Vins", and one company of the Mahony Jäger. With their approach masked by fog and darkness, the small force surprised the Brescia garrison on the morning of 30 July, capturing not only the 600–700 French soldiers stationed there, but also three officials of the French Directory: Jean Lannes, Joachim Murat, and François Étienne de Kellermann. However, within two days, Klenau's force had to face Napoleon Bonaparte and 12,000 Frenchmen; his small advance guard was quickly pushed out of Brescia on 1 August. At the subsequent Battle of Lonato of 2–3 August 1796, the French forced Quasdanovich's column to withdraw into the mountains. This isolated Quasdanovich's force from Wurmser's main army by Lake Garda, and freed the French to concentrate on the main force at Castiglione delle Stiviere, further south; Bonaparte's victory at the Battle of Castiglione forced Wurmser across the Mincio River, and allowed the French to return to the siege of Mantua.