Chartered by the Navy in September 1858, she served as USS Memphis during the Paraguay expedition of late 1858 and early 1859.

During the first part of the Civil War Mystic served in the Union blockade of the Confederacy's Atlantic Ocean Coast.

She assisted in the capture or destruction of four blockade runners off the coast of North Carolina in June–September 1862, among them the steamers Emma and Sunbeam.

In May 1863 she supported the Union Army during an expedition up the York River and in September of that year seized a sailing vessel off Yorktown, Virginia.

This article incorporates text from the public domain Dictionary of American Naval Fighting Ships.