Napoleon made him a peer of France, and gave him command of the I Corps, which formed part of the Army of the North. On 16 June 1815 during the first major engagements of Waterloo Campaign, due to conflicting orders his Corps spent the day on the Old Roman Road marching and counter marching between the battles of Quatre Bras and Ligny without engaging in either battle. He was not, however, held to account by Napoleon, and as the latter's practice in such matters was severe to the verge of injustice, it may be presumed that the failure was not due to d’Erlon. If the I Corps had engaged in either battle the outcome of the campaign might have been different.