"Mirth" was laid down on 31 July 1943 at Lorain, Ohio, by the American Shipbuilding Company, launched on 24 December 1943, sponsored by Mrs. B. E. Gathercoal, and commissioned on 12 August 1944 with Lieutenant M. A. Rusteen, USNR, in command.After shakedown in the Chesapeake Bay, "Mirth", a unit of Mine Division 37, got underway on 29 November 1944 for brief duty with Naval Operating Base Bermuda.