From 12 November 1819 to 24 April 1820, "Constellation" served as flagship of Commodore Charles Morris on the Brazil Station, protecting American commerce against privateers and supporting the negotiation of trade agreements with South American nations. On 25 July 1820, it sailed for the first time to Pacific waters and arrived in Valparaíso, Chile under Charles G. Ridgeley in January 14, 1821. He was then relieved by Commodore Charles Stewart in April 1822. It remained thus employed for two years, protecting American shipping off the coast of Peru, an area where disquiet erupted into revolt against Spain.