On 15 September, Iosco towed the USS General Burnside, which had been stuck on a reef, and was then sent to join the North Atlantic Blockading Squadron.

While operating off Wilmington, North Carolina, on 21 November, Iosco captured the blockade runner CSS Sybil.

During December 1864 and January 1865, she participated in the assaults on Fort Fisher, which ultimately closed Wilmington as a Confederate port.

During the first assault, Iosco engaged the batteries at Mound Fort, and hit the Confederate flag flying over the fortification, knocking it down.

USS Iosco was decommissioned in July 1865 and in February 1868 was converted into a coal hulk for service at the New York Navy Yard.