 When the War of the First Coalition broke out, he took command of the frigate "Résolue" and raided commerce in the Atlantic, in the Bay of Biscay, and the Channel, both alone and within the frigate division commanded by Zacharie Allemand.A resolute Republican, Nielly had his crew sign a manifesto supporting the Constitution of the French First Republic, and sent it to the National Convention.In November 1793, he was promoted to "contre-amiral".