She was commissioned in October 1806 under the command of Lieutenant George Le Blanc. She was ordered to carry dispatches to the squadron blockading Bordeaux. When she met up with Naiad on 13 August 1807, Le Blanc left Cassandra to take the dispatches to Naiad. Two sudden squalls rolled Cassandra over on her beam ends, capsizing her and causing her to sink stern first. Eleven men, and one woman and her child drowned.