Assigned to the North Atlantic Blockading Squadron, on 25 July Hero was renamed Moccasin.

She acted as guard boat off Fort Delaware until 13 August when Moccasin joined tug Aster and Yantic in pursuit of blockade‑runner CSS Tallahassee.

On 13 March 1865 Moccasin was ordered to St. Inigoes, Maryland, for duty with the Potomac Flotilla under Commander Foxhall A. Parker, Jr. Lee surrendered to Grant at Appomattox 9 April, but the news was slow in spreading.

On 30 July Wyandank took Moccasin in tow for Norfolk, Virginia where the tug debarked patients from the Washington, DC, naval hospital.

Upon return to Washington, Moccasin was decommissioned 12 August and sold 18 September 1865 to the Treasury Department for use as a revenue cutter.