In the War of the Third Coalition, Beaumont led the 3rd Dragoon Division, which included 18 squadrons in the 5th, 8th, 9th, 12th, and 16th Dragoon Regiments, and a horse artillery battery. His brigadiers were Charles Joseph Boyé and Nicolas-Joseph Scalfort. Under the overall leadership of Marshal Joachim Murat, he led his 2,400 troopers into action at the Battle of Wertingen on 8 October 1805. The French cavalry, including Beaumont's division, Louis Klein's 1st Dragoon Division, Anne-François-Charles Trelliard's Light Cavalry Brigade, and Étienne Marie Antoine Champion de Nansouty's 1st Cuirassier Division, marched from Rain early that morning. Moving south along the Lech River to Nordendorf, they turned west and appeared before Franz Xavier Auffenburg's 5,400 Austrians at Wertingen.