RMS Britannia was an ocean liner of the British and North American Royal Mail Steam Packet Company, later known as Cunard Steamship Company. She was launched on 5 February 1840, at the yard of Robert Duncan & Company in Greenock, Scotland. The ship and her sisters, Acadia, Caledonia, and Columbia, were the first ocean liners built by the company.
Britannia was a large ship for the period, 207 feet (63 m) long and 34 feet (10.3 m) across the beam, with three masts. She had paddle wheels and her two-cylinder side-lever engine (from Robert Napier) had a power output of about 740 indicated horsepower. She was relatively fast for the time: her usual speed was about 8.5 knots (16 km/h), but she could do better if the winds and currents were favourable. She had a tonnage, or carrying capacity, of 1,154 tons (by the Builder's Old Measurement). She was capable of carrying 115 passengers with a crew of 82. On her maiden voyage, starting on 4 July 1840, she made Halifax, Nova Scotia, from Liverpool, England, in 12 days and 10 hours, continuing on to Boston, Massachusetts. The Britannia transported numerous types of cargo alongside its passengers. The cargo included 600 tons of coal; mail due across the Atlantic; livestock for food and milk; and cats to control the rat population. There were 115 first class passengers, with 89 crew members on board.
She was joined by her sister ship Acadia in August 1840, by Caledonia in October 1840 and by Columbia in January 1841. All four ships could carry 115 passengers and 225 tons of cargo. The dining saloon was a long deck-house placed on the upper deck and there was also a 'ladies only' saloon. The fare to Halifax was 35 guineas (2,964 GPB in 2015) which included wines and spirits as well as food.
In March 1849 she was sold by Cunard to the revolutionary German Empire Navy and was renamed SMS Barbarossa. She had nine guns fitted, and was the flagship of the Reichsflotte under Karl Rudolf Brommy in the Battle of Heligoland. In June 1852 she was transferred to the Prussian Navy and used as a barracks ship at Danzig. In May 1880 she was decommissioned from the Prussian Navy and in July 1880 she was sunk as a target ship.