USS Hartford, a sloop-of-war steamer, was the first ship of the United States Navy named for Hartford, the capital of Connecticut. Hartford served in several prominent campaigns in the American Civil War as the flagship of David G. Farragut, most notably the Battle of Mobile Bay in 1864. She survived until 1956, when she sank awaiting restoration at Norfolk, Virginia.

Hartford was launched on 22 November 1858 at the Boston Navy Yard; sponsored by Miss Carrie Downes, Miss Lizzie Stringham, and Lieutenant G. J. H. Preble; and commissioned on 27 May 1859, Captain Charles Lowndes in command. After shakedown out of Boston, the new screw sloop of war, carrying Flag Officer Cornelius K. Stribling, the newly appointed commander of the East India Squadron, sailed for the Cape of Good Hope and the Far East. Upon reaching the Orient, Hartford relieved Mississippi as flagship. In November, she embarked the American Minister to China, John Elliott Ward, at Hong Kong and carried him to Canton, Manila, Swatow, Shanghai, and other Far Eastern ports to settle American claims and to arrange for favorable consideration of the Nation's interests.

With the outbreak of the American Civil War, Hartford was ordered home. She departed the Sunda Strait with Dacotah on 30 August 1861 and arrived Philadelphia on 2 December to be fitted out for wartime service. She departed the Delaware Capes on 28 January as flagship of Flag Officer David G. Farragut, the commander of the newly created West Gulf Blockading Squadron. (See also: Confederate blockade mail.)

An even larger purpose than the important blockade of the South's Gulf Coast lay behind Farragut's assignment. Late in 1861, the Union high command decided to capture New Orleans, the South's richest and most populous city, to begin a drive of sea-based power up the Mississippi River to meet the Union Army which was to drive down the Mississippi valley behind a spearhead of armored gunboats. "Other operations," Secretary of the Navy Gideon Welles warned Farragut, "must not be allowed to interfere with the great object in view—the certain capture of the city of New Orleans."

Hartford arrived 20 February at Ship Island, Mississippi, midway between Mobile Bay and the mouths of the Mississippi. Several Union ships and a few Army units were already in the vicinity when the squadron's flagship dropped anchor at the advanced staging area for the attack on New Orleans. In ensuing weeks a mighty fleet assembled for the campaign. In mid-March Commander David Dixon Porter's flotilla of mortar schooners arrived towed by steam gunboats.

The next task was to get Farragut's ships across the bar, a constantly shifting mud bank at the mouth of each pass entering the Mississippi. Farragut managed to get all of his ships but Colorado across the bar and into the river where Forts St. Philip and Jackson challenged further advance. A line of hulks connected by strong barrier chains, six ships of the Confederate Navy—including ironclad Manassas and unfinished but potentially deadly ironclad Louisiana, two ships of the Louisiana Navy, a group of converted river steamers called the Confederate River Defense Fleet, and a number of fire rafts also stood between Farragut and the great Southern metropolis.

On 16 April, the Union ships moved up the river to a position below the forts, and David Dixon Porter's gunboats first exchanged fire with the Southern guns. Two days later his mortar schooners opened a heavy barrage which continued for six days. On the 21st, the squadron's Fleet Captain, Henry H. Bell, led a daring expedition up river and, despite a tremendous fire on him, cut the chain across the river. In the early hours of 24 April, a red lantern on Hartford's mizzen peak signaled the fleet to get underway and steam through the breach in the obstructions. As the ships closed the forts their broadsides answered a fire from the Confederate guns. Porter's mortar schooners and gunboats remained at their stations below the southern fortifications covering the movement with rapid fire.

Hartford dodged a run by ironclad ram Manassas; then, while attempting to avoid a fireraft, grounded in the swift current near Fort St. Philip. When the burning barge was shoved alongside the flagship, only Farragut's leadership and the training of the crew saved Hartford from being destroyed by flames which at one point engulfed a large portion of the ship. Meanwhile, the sloop's gunners never slackened the pace at which they fired into the forts. As her firefighters snuffed out the flames, the flagship backed free of the bank.