Batatalion Commander Calès was finally sent to combat in October 1806 and fought during the campaigns of Prussia (1806) and Poland (1807). He did not however participate neither to the famous battle of Jena, nor to that of Auerstedt (both conducted in parallel on 14 October 1806, and where the Prussian army was literally swept by the French troops), because the Division Leval, which included his 4th regiment, could not arrive on time at Jena. He distinguished himself however at the "fight of Bergfried" (3 February 1807), a prelude to the battle of Eylau: