 At the New York Navy Yard, "De Soto" was fitted out for naval service, including the installation of a battery consisting of one 30-pounder Parrott rifle and eight 32-pound guns.She was then commissioned as USS "De Soto", with Commander William M. Walker placed in command.The steamer put to sea on 19 November with ordnance stores for Fort Pickens, Florida, and vessels in the Gulf of Mexico, arriving off Southwest Pass, Mississippi River, after 11 December.