USS Mahaska, a 1070-ton Sebago class "double-ender" steam gunboat built at the Portsmouth Navy Yard, Kittery, Maine, was commissioned in May 1862. During 1862 and into 1863, she was active in support of Federal operations against the Confederates along the Virginia rivers and Chesapeake Bay. Sent to join the blockade off Charleston, South Carolina, Mahaska participated in attacks on that port's defending fortifications during August 1863. In February-August 1864 she served along the east coast of Florida, taking part in expeditions against Jacksonville and Saint Marks.

Overhauled at Boston, Massachusetts, in the last part of 1864, Mahaska was active off Florida to the end of the Civil War and continued to operate in Southern waters for another three years. She was placed out of commission in September 1868 and was sold in November of that year. Thereafter, she was briefly employed as the merchant vessel Jeannette.