USS Britannia was a steamer captured by the Union Navy during the American Civil War. She was used by the Union Navy as a gunboat and patrol vessel in support of the Union Navy blockade of Confederate waterways. In 1862, Barclay, Curle & Co. Ltd., Glasgow, shipbuilders launched the iron-hulled, side-wheel paddle steamer Britannia. She was first registered to the Leith, Hull & Hamburg company of Leith, Scotland. In January 1863, she was acquired by Leach, Harrison & Forward of Liverpool to run through the Union Navy's blockade of the Confederate coast during the American Civil War.