Exelmans was ordered to hold the right flank during the Battle of Ligny on 16 June. On the 17th, he accurately reported the position of 20,000 Prussians at Gembloux, but he was unable to interfere with their retreat, having only 3,000 cavalry. On that day, his corps was placed under the command of Marshal Emmanuel de Grouchy. On 18 and 19 June at the Battle of Wavre, Exelmans' corps played only a small role. During the fighting on the 19th, Strolz held the extreme left flank on the west bank of the Dyle River while Chastel watched the far right flank on the east bank. There was a clash at Namur on the 20th in which the 20th Dragoon Regiment of the II Cavalry Corps was engaged.