In 1805, Klein's division was part of the newly created VIII. Corps, under command of Édouard Mortier; the role of the Corps was to patrol and secure the northern shore of the Danube river, limiting the Austro-Russian activity. Napoleon incorrectly assumed that the Russians and the Austrians would make a stand near St. Pölten, northwest of Vienna. Klein's entire regiment of dragoons patrolled the northern Danube shore, while the rest of his division, the last in the extended line of march, was more than a day behind Maxime Gazan's lead division. Klein's division did not take part in the Battle of Dürenstein, although his dragoons were with Mortier and Gazan immediately prior to the engagement.