They had to put aside their differences during the French invasion of Russia, when Morand's division formed part of Davout's renumbered I Corps. Crossing the Niemen on 24 June 1812, he fought at Smolensk and had his jaw smashed by a shell splinter at the Battle of Borodino. He continued to lead his division in the retreat from Moscow, being one of the last formations to leave the city. Fighting at Vyazma and Krasnoi, by the time he reached the Niemen he had just 300 left of the original 10,000 men under his command.