Before the Revolution he went to Paris to study law, and here he became a political journalist, a Jacobin and a friend of Danton. He was appointed in 1793 to a superior command in the army direct from civil life, and as a general of brigade he took part in the fighting of the 13th Vendémiaire. In 1796 he fought under Bonaparte in Italy, and was promoted general of division for good service in the field.
In 1798 he commanded the French army which occupied Switzerland, and in the following year he was in command of the French troops in the Netherlands. His defence of Amsterdam against the Anglo-Russian expedition under the duke of York was completely successful; the invaders were defeated, and compelled, after a miserable retreat, to re-embark. He rendered further good service in Vendée and in Italy, and was made a marshal by Napoleon on the assumption by the latter of the imperial title in 1804.
In 1807 Brune held a command in North Germany, but he was not afterwards employed during the First Empire. It is said that he was accused of venality, and on that account disgraced, but of this there is no proof. He was recalled to active service during the Hundred Days, and as commander of the army of the Var he defended the south of France against the Austrians. He was murdered by royalists during the White Terror at Avignon.
See Notice historique sur la vie politique et militaire du marechal Brune (Paris, 1821), and Vermeil de Conchard, L'Assassinat du marechal Brune (Paris, 1887).