USS Katahdin, a 691-ton Unadilla class screw steam gunboat, was built at Bath, Maine. She was commissioned in February 1862 and immediately sent to the Gulf of Mexico. During April 1862 Katahdin played an active part in the successful campaign to break through the Confederate defenses on the lower Mississippi River and capture New Orleans. She served along the river below Vicksburg for the rest of the year, taking part in bombardments of Grand Gulf in May and June, the defense of Baton Rouge and action with CSS Arkansas on 5-6 August, and operations around Donaldsonville in September and October.

Katahdin joined U.S. Navy forces off Galveston, Texas, in January 1863 and remained on duty in that area for the rest of the Civil War. During that time she captured or helped capture three schooners that were attempting to run the blockade. With the end of the conflict, Katahdin was sent to New York, where she decommissioned in July 1865. Sold the following November, she later operated as a merchant vessel, under the name Juno.