In 1796, he served under Napoleon Bonaparte in the Italian campaign and was promoted to général de division allegedly so as to avoid Napoleon having to concede the post to Bernadotte, who was at this time a political rival to Napoleon. Brune was noted as having been particularly incompetent; one anecdote has him attempting to march three divisions down the same road, leading to confusion among the army of Italy. He was subsequently removed from command. Brune commanded the French army that occupied Switzerland in 1798 and established the Helvetic Republic. In the following year, he was in command of the French troops in defence of Amsterdam against the Anglo-Russian invasion of Holland under the Duke of York, in which he was completely successful – the Anglo-Russian forces were defeated in the Battle of Castricum, and compelled, after a harsh retreat, to re-embark. He rendered further good service in Vendée and in the Italian Peninsula from 1799 to 1801, winning the 1800 Battle of Pozzolo.
In 1796, he served under Napoleon Bonaparte in the Italian campaign and was promoted to général de division allegedly so as to avoid Napoleon having to concede the post to Bernadotte, who was at this time a political rival to Napoleon. Brune was noted as having been particularly incompetent; one anecdote has him attempting to march three divisions down the same road, leading to confusion among the army of Italy. He was subsequently removed from command. Brune commanded the French army that occupied Switzerland in 1798 and established the Helvetic Republic In the following year, he was in command of the French troops in defence of Amsterdam against the Anglo-Russian invasion of Holland under the Duke of York, in which he was completely successful – the Anglo-Russian forces were defeated in the Battle of Castricum, and compelled, after a harsh retreat, to re-embark. He rendered further good service in Vendée and in the Italian Peninsula from 1799 to 1801, winning the 1800 Battle of Pozzolo.