Louis-Victor-Léon de Rochechouart entered the Russian army at the rank of sous-lieutenant and became aide de camp to the duke of Richelieu. He rose through the ranks, serving as a lieutenant in the imperial guard, then aide de camp de l'empereur Alexander I of Russia. From 1805 to 1812, he participated in the conquest of Bessarabia and Circassia, fought in Caucasia and Chechnya. When France invaded Russia in 1812, Rochechouart was mobilised in general Tormassov's army. He participated in the capture of Minsk, then at Berezina, where he witnessed the tragic crossing of the river by the French army. He summed up the Russian campaign thus: