The SS Great Britain was the second ship of the trio designed by the innovative and farsighted engineer I. K. Brunel; the other two were the Great Western and the Great Eastern.

On a number of counts, the Great Britain represents a milestone in the history of shipbuilding. She was by far the largest ship of her day, one-third again as long as the biggest ship of the line in the Royal Navy. She was the first seagoing ship to be built of iron.

Though Great Britain was not a commercial success on the Atlantic run for her builders, many of the ship's innovations were adopted in the years following her completion.

Originally conceived as a companion vessel for the Great Western—a wooden paddle steamer to be named City of New York—Brunel soon determined that great economies could be achieved, especially in the stowage of coal fuel, in a larger ship. After assessing the seakeeping qualities of the iron-hulled paddle steamer Rainbow in her service between England and Belgium, he changed the hull material to iron.

Finding no takers for the construction of their ship, the Great Western Steamship Company decided to build the vessel themselves, which entailed the construction of a drydock, known as the Great Western (later Wapping) Dock. The company also decided to build the engines for the enormous paddlewheels intended for the ship, at this stage known as Mammoth.

In 1840, during construction of the Great Britain, Brunel studied the screw propulsion system of the SS Archimedes and decided to adopt a single-screw propeller for his new ship. The change to a propeller also meant radical changes to the engines. The final design included four cylinders, each 88 inches in diameter. Operated at 18 revolutions per minute, the engine drove the propeller, to which it was connected via a drive chain, at 53 rpm. The propeller itself, of iron, was 15.5 feet in diameter and weighed more than 3 tons. All told, the engines and boilers weighed 520 tons, while 1,040 tons of iron were in the hull. The ship also carried six masts. All but one, the second from the bow, were fore-and-aft rigged. After all, sail was considered to be more reliable than steam.

The Great Britain's luxurious accommodations included 26 single and 113 double cabins and it had a cargo capacity of 1,000 tons. There were bunkers for 1,000 tons of coal. When the ship cleared Bristol's Floating Harbor, it was found that the locks were too narrow, and the company had to widen them.

Sea trials began on December 13, 1844, in which the Great Britain achieved a speed of 11 knots. After a six-month stay in London where she was visited by thousands of admirers, including Queen Victoria, in June she sailed to Liverpool and loaded cargo for New York. She sailed on July 26 under command of Great Western veteran James Hoskens and arrived on August 10 after a crossing of 14 days, 21 hours. Her return to Bristol took about the same time.

During her second voyage, most of the propeller blades fell off and a new four-bladed screw had to be fitted. The engines were also reconfigured by Maudslay Sons and Field, and produced 1,663 indicated horsepower, up from 686. Subsequent voyages were marred by technical problems of varying severity, but on her fifth voyage, outward bound from Liverpool with 180 passengers (a record for a North Atlantic steamship), she ran aground on a high tide on September 22, 1846, in Dundrum Bay south of Belfast Lough in Ireland. Although there was no loss of life, it was not until August 27, 1847, that the ship was freed, with the help of the steam frigate HMS Birkenhead. Unable to pay for the necessary work, the Great Western Steamship Company was forced to sell the ship.

It was three years before the ship was purchased by Gibbs, Bright & Company (who had underwritten construction). With a new three-blade screw driven by a two-cylinder engine with a simple gear drive, and the masts reduced to four (square-rigged on the middle two masts), the ship reentered service on the transatlantic run, transferring to the Australia trade after one voyage.

Leaving the Mersey on August 21, 1852, with 650 passengers, the Great Britain arrived in Melbourne on November 12, after a run of 82 days. She departed Australia in January with 260 passengers and £550,000 in gold dust.

Rerigged again, as a three-masted ship, the vessel was sold to the Liverpool & Australian Navigation Company, and sailed from Liverpool with more than 1,000 passengers. Except for service as a troop transport during the Crimean War (1855-56) and one voyage during the Indian Mutiny in 1857, the Great Britain remained in the Australian passenger trade until laid up in Birkenhead in February 1876.

Acquired the next year by Antony Gibbs, Sons and Company, for bulk trade between Britain and San Francisco as a sailing ship, the Great Britain was stripped of her engines and the hull was sheathed in wood. On her third voyage out, on February 25, 1886, she was forced back to Stanley, Falkland Islands, and condemned. After 47 years as a coal and wool storage ship, the Falkland Islands Company moved her from Stanley to nearby Sparrow Cove, where the ship was abandoned.

In 1967, after an appeal to save the ship was initiated by E. C. B. Corlett—a similar idea had been floated by the San Francisco Maritime Museum—the Great Britain Project Committee was formed to bring the ship back to Bristol for restoration to her original design. In a salvage exercise that would have impressed Brunel himself, on April 24, 1970, the ship was towed from Stanley aboard a pontoon barge, stopping first at Montevideo, and then on to Bristol where she eased into Wapping Dock on July 19, the anniversary of her launch.