USS Shepherd Knapp was a large (838-ton) ship with eight guns, purchased by the Union Navy during the beginning of the American Civil War.

Her commanding officer was Acting Volunteer Lieutenant Henry S. Eytinge, who was ordered on 1 November 1861 to cruise in the West Indies seeking to capture or destroy any "vessels of the rebels" he might encounter.

[2] The special object of his attention was the Confederate commerce raider, CSS Sumter, which had been preying on Union shipping since early summer.

[4] In November, Shepherd Knapp was back in New York and by early February 1863 she was heading to the West Indies seeking Confederate ships, especially CSS Alabama.

As a sailing ship it was unlikely that Shepherd Knapp could overhaul a steam-powered raider such as CSS Alabama, powered by two 300 hp engines.