USS Mackinaw, an 1173-ton Sassacus class side-wheel "double-ender" steam gunboat built at the New York Navy Yard, was commissioned in April 1864. For much of that year, she served on the James River, Virginia, taking part in engagements at Dutch Gap in August. In early December, while on blockade duty, Mackinaw captured a sailing blockade runner. Later in that month, and in January 1865, she took part in ultimately successful assaults on Fort Fisher, North Carolina. In February, the gunboat operated on the Cape Fear River, N.C.
Decommissioned in May 1865, as the war came to an end, Mackinaw returned to active service in January 1866. She spent more than a year with the North Atlantic Squadron and in the West Indies, but was decommissioned again in May and sold in October of 1867.
