USS Hetzel, a 301-ton (burden) side-wheel steam gunboat, was originally built at Baltimore, Maryland, in 1845 as a commercial vessel. She was acquired by the U.S. Coast Survey in 1849 and, after the beginning of the Civil War in 1861, was transferred to the Navy. Placed in commission in August 1861, Hetzel's first combat action took place in Hampton Roads, Virginia, on 2 December, when she took part in an engagement with CSS Patrick Henry. In February and March 1862 she participated in the campaign that captured Roanoke Island, Elizabeth City and New Bern, thus bringing much of the North Carolina Sounds area under Federal control.

Hetzel was active in that region for the rest of the Civil War. During November 1862 she supported operations against Plymouth, Hamilton, and Williamston, N.C., and on 13-14 March 1863 helped to defend Fort Anderson, near New Bern, against a Confederate attack. Her other activities included serving as Union Navy flagship in the Sounds area and sharing in the capture of several vessels that attempted to violate the blockade. Under repair from November 1864, Hetzel returned to the North Carolina Sounds in late May 1865, after the end of the conflict, and remained there until October of that year, when she was returned to the Coast Survey.