USS Guard was a fourth-class ship-rigged sailing vessel, armed with four 8-inch (203 mm) Dahlgren guns and one 21-pdr howitzer, acquired by the Union Navy during the American Civil War. She was placed into service as a storeship and assigned to support the ships blockading the ports of the Confederate States of America. Post-war she was recommissioned several times for various tasks including supporting the American fleet stationed in Europe with supplies and participating in the Darien expedition.