In 1854, after years of experimentation with various forms of steam propulsion, the United States Navy committed itself to the development of capital ships driven by screw propellers. That year congressional appropriations to build a new class of steam frigates marked the transitional point in American naval propulsion from steam-driven paddlewheels to modern propellers.

These ships, later to be identified as the Merrimack class of frigates, consisted of five ships — the Merrimack, Colorado, Roanoke, Wabash, and Minnesota. The Merrimack, the first of the class launched, was built at the Boston Navy Yard and completed in 1855. At that time, the Merrimack was considered perhaps the most modern naval vessel afloat. Heavily armed, she carried 40 cannon in her batteries ranging in caliber from 8- to 10-inch guns. In compliance with naval standards of the time, though the new frigate was a steamship, she was also a fully rigged sailing vessel. It was expected that sail would be the primary means of propelling the ship, and that her steam engines would simply provide auxiliary power. Her steam plant consisted of two horizontal stroke engines fueled by four boilers that generated 972 horsepower at the cost of 2,800 pounds of coal per hour. Measuring 275 feet in length and 38 feet in the beam, the wooden vessel presented an impressive silhouette.

For all her promise as the most modern of warships, the Merrimack proved somewhat disappointing. During her initial trials along the East Coast, mechanical failures cropped up that plagued her throughout her career. In 1855, on her fourth day out on a cruise from Norfolk to Havana, the Merrimack broke her propeller. Returning from Havana to Key West, she lost her rudder and had to be towed into Key West. She was then towed back to Boston for repairs. Other defects were also noted by her crew: her tendency to roll heavily in the sea, and the tendency of her boilers to overheat when under pressure. Furthermore, her deep draft of 23 feet prevented her from entering most harbors of the American coast.

Once again ready for sea in 1857, the Merrimack was sent on a European cruise. In large part this mission was designed to impress the Old World powers with the new technology of the United States Navy. The Merrimack was well received in Europe. The British noted the heavy guns carried by the American frigate as well as her smaller size and greater maneuverability compared to British ships of the line. In fact the British were well enough impressed with the Merrimack that the Admiralty ordered ships of similar size and design to be constructed. However, the British did note a major deficiency in the Merrimack — her lack of speed. The Merrimack averaged only 8 knots when under both steam and sail — a speed that would not allow her to elude a larger, more powerful enemy.

Following her European tour, the Merrimack was dispatched to the Pacific, where she remained until 1860, when continuing engine problems forced her to be recalled to the Gosport Navy Yard for repairs. In Gosport, after an inspection of her worn and faulty power plant, the Merrimack's engines were condemned, and the ship was put into ordinary for major refitting and repair. The Merrimack was still at Gosport in 1861 when the shipyard fell into the hands of the Confederacy in April.

On April 20, 1861, in order to prevent valuable supplies and property from falling into the hands of the Confederacy, Union forces burned most of Gosport's repair facilities. The Merrimack, still in a state of disrepair, was also set afire by Union sailors. The ship burned quickly to the waterline, and then her hull sank into the mud of the Elizabeth River.