By the summer of 1864, Mobile, Alabama was one of only two major Confederate ports still open (the other being Wilmington, North Carolina), making the city a vital lifeline for supplies from the outside world. While the Union Navy had established a blockade at the port, Mobile Bay’s formidable defenses prevented the navy from closing the net too tightly, and rebel smugglers continued to slip in and out.
The bay had two main channels of entry defended by three forts, the largest being Fort Morgan – a 45-gun, star-shaped fortification protecting the largest channel. To supplement these defenses, the Confederates had filled parts of the channel with torpedoes (which today would be called sea mines), and assembled a small flotilla of one ironclad, the C.S.S. Tennessee, and three gunboats. The fleet was commanded by veteran seaman Adm. Franklin Buchanan – who had earned his place in history commanding C.S.S. Virginia on the first day of the Battle of Hampton Roads. Tasked with closing the port was David G. Farragut, who had become the United States’ first admiral after his capture of New Orleans two years previous. Farragut assembled a fleet consisting of four ironclad monitors and more than a dozen wooden ships. At 7:00 a.m. on August 5, 1864, the Federals rushed into the harbor.
Farragut split his fleet into two columns – the ironclads sailing nearest Fort Morgan, and the wooden ships on the far side. Farragut ordered the larger wooden ships lashed side by side to a smaller ship so that the bigger vessels could serve as a shield, and so the ships would be able to tow each other if one became crippled. Farragut personally observed much of the battle while lashed to the rigging on his flagship U.S.S. Hartford.
Initially, the ships began sailing through the narrow width of the channel that had not been mined – passing under the guns of the fort. But as the columns maneuvered, the ships found themselves drifting into the edge of the minefield. The ironclad U.S.S. Tecumseh struck a torpedo, and sank almost instantly, and cautious Union captains began stopping their ships while still within range of Fort Morgan. At this juncture, Farragut is said to have ordered Hartford forward with the famous line "Damn the torpedoes! Full speed ahead!" (although more reliable accounts suggest a slight variation to this quote).
Although they faced bombardment from the fort and the Confederate ships, Farragut’s flagship made it through the minefield in one piece, with the rest of the fleet following his path. Once into the expansive bay, the fleet could easily move out of range of Fort Morgan’s guns, leaving only the Confederate ships to contend with. The Federals quickly captured or drove away the Rebel gunboats, but despite the overwhelming odds the Tennessee, Buchanan’s flag ship, raced out to meet the Northerners head on.
Buchanan was soon surrounded by the Union ironclads as he steered for the Hartford, but the Tennessee’s armored plating protected her as she was repeatedly rammed and pounded with shot. However, the ship’s weak engine – a product of the Confederacy’s limited industrial capacity – made her too slow to outmaneuver her adversaries, and prevented her from successfully ramming any of the Union ships – although she came close, sliding alongside Hartford as the two crews fired at near point-blank range.
Eventually, however, the Rebels’ slow engine, bad gunpowder, and numerical disadvantage took their toll. Buchanan was injured and the ship’s rudder chains were cut – preventing her from steering, and allowing the Federals to move away from her guns and continue pummeling the Tennessee in relative safety. Three hours after the fighting had started, C.S.S. Tennessee surrendered, leaving the harbor in Union control, and closing the port to Southern blockade runners. The city of Mobile itself was too well defended to capture, but several weeks of joint Army-Navy operations managed to capture Fort Morgan and the other forts protecting the harbor. All told, the Union suffered over 300 casualties in the fighting compared to less than 50 for the Confederates, although by the time the forts surrendered, 1,500 Southerners had been captured.