The vessel was constructed in Leith, Scotland, originally laid down as the civilian yacht Agawa for William L. Harkness and launched on 20 September 1906.

The United States Navy leased the vessel from Harkness in 1917 for World War I service in the section patrol.

She departed Newport on 1 November 1917 with her squadron, and escorted and towed submarine chasers to European waters before arriving at Gibraltar on 29 December 1917.

After Cythera served as a civilian vessel for more than two decades, the U.S. Navy reacquired her from Harkness's widow Edith on 31 December 1941 for World War II service.

On 2 May 1942, while escorting the Soviet tanker SS Ashkhabad, she was torpedoed and sunk by the German submarine U-402 in the Atlantic Ocean off the coast of North Carolina.