The colonel led a retreat back to prepared defensive lines near the Penitentiary, under the protection of the Union warships. The Confederate troops began coming under fire from the gunboats. The Confederate ram "Arkansas" arrived not long after but her engines failed just four miles above the city. Her commander ordered her set afire to prevent her capture. Without any prospect of naval support, Breckenridge was unable to attack the Union positions and withdrew. Union troops evacuated the city a week later, concerned for the safety of New Orleans, but returned that autumn. Confederates occupied Port Hudson, which they held for almost another year.