From the Civil War Naval Encyclopedia.
In July 1861, George Hollins commanded the New Orleans Naval Station. In October of that year, he seized the Manassas, a privately owned merchant ship undergoing conversion into a privateer ironclad ram. He then ordered it and the other ships of his squadron to attack the Union squadron.
These blockading ships were under the command of Captain John Pope and located downriver from New Orleans at the Head of Passes. Hollins and his ships drove them away on October 12 in what became known as "Pope's Run."