The Second Battle of Fort Fisher was a successful assault by the Union Army, Navy and Marine Corps against Fort Fisher, south of Wilmington, North Carolina, near the end of the American Civil War in January 1865. Sometimes referred to as the "Gibraltar of the South" and the last major coastal stronghold of the Confederacy, Fort Fisher had tremendous strategic value during the war, providing a port for blockade runners supplying the Army of Northern Virginia.

Alfred Terry had previously commanded troops during the Second Battle of Charleston Harbor and understood the importance of coordinating with the Union Navy. He and Admiral Porter made well laid out plans for the joint attack. Terry would send one division of United States Colored Troops under Charles J. Paine to hold off Hoke's division on the peninsula. Terry's other division under Adelbert Ames, supported by an independent brigade under Colonel Joseph Carter Abbott, would move down the peninsula and attack the fort from the land face, striking the landward wall on the river side of the peninsula. Porter organized a landing force of 2,000 sailors and marines to land and attack the fort's sea face, on the seaward end of the same wall.

On January 13, Terry landed his troops in between Hoke and Fort Fisher. Hoke was unwilling to risk opening the route to Wilmington and remained unengaged while the entire Union force landed safely ashore. The next day Terry moved south towards the fort to reconnoiter the fort and decided that an infantry assault would succeed.

On January 15, Porter's gunboats opened fire on the sea face of the fort and by noon they succeeded in silencing all but four guns. During this bombardment Hoke sent about 1,000 troops from his line to Fort Fisher, however only about 400 were able to land and make it into the defense while the others were forced to turn back. Around this time the landing party of 1,600 sailors and 400 marines, led by Lieutenant Commander Kidder Breese, landed and moved against the point where the fort's land and sea faces met, a feature known as the Northeast Bastion. The Union Army's original plan was for the naval force, armed with revolvers and cutlasses, to attack in three waves with the marines providing covering fire, but instead, the assault went forward in a single unorganized mass. General Whiting personally led the defense and routed the assault, with heavy casualties in the naval force.

The attack, however, drew Confederate attention away from the river gate, where Ames prepared to launch his attack. At 2:00 p.m. he sent forward his first brigade, under the command of Brevet Brigadier Newton Martin Curtis, as Ames waited with the brigades of Colonels Galusha Pennypacker and Louis Bell. An advance guard from Curtis's brigade used axes to cut through the palisades and abatis. Curtis's brigade took heavy casualties as it overran the outer works and stormed the first traverse. At this point Ames ordered Pennypacker's brigade forward, which he accompanied into the fort. As Ames marched forward, Confederate snipers zeroed in on his party, and cut down a number of his aides from around him. Pennypacker's men fought their way through the riverside gate, and Ames ordered a portion of his men to fortify a position within the interior of the fort. Meanwhile, the Confederates turned the cannons in Battery Buchanan at the southern tip of the peninsula and fired on the northern wall as it fell into Union hands. Ames observed that Curtis's lead units had become stalled at the fourth traverse, and he ordered forward Bell's brigade, but Bell was killed by sharpshooters before ever reaching the fort.[18] Seeing the Union attackers crowd into the breach and interior, Whiting took the opportunity to personally lead a counterattack. Charging into the Union soldiers, Whiting received multiple demands to surrender, and when he refused he was shot down, severely wounded.

Porter's gunboats helped maintain the Federal momentum. His gunners' aim proved to be deadly accurate and began clearing out the defenders as the Union troops approached the sea wall. Curtis's troops gained the heavily contested fourth traverse. Lamb began gathering up every last soldier in the fort, including sick and wounded from the hospital, for a last-ditch counterattack. Just as he was about to order a charge, he fell severely wounded and was brought next to Whiting in the fort's hospital. Ames made a suggestion for the Union troops to entrench in their current positions. Upon hearing this notion, a frenzied Curtis grabbed a spade and threw it over Confederate trenches and shouted, "Dig Johnnies, for I'm coming for you." About an hour into the battle, Curtis fell wounded while going back to confer with Ames. Pennypacker also fell wounded before the battle ended.

The grueling battle lasted for hours, long after dark, as shells plunged in from the sea and Ames struggled with a division that became increasingly disorganized as his regimental leaders and all of his brigade commanders fell dead or wounded. Terry sent forward Abbott's brigade to reinforce the attack, then joined Ames in the interior of the fortress. Meanwhile, in Fort Fisher's hospital, Lamb turned over command to Major James Reilly, and Whiting sent one last plea to General Bragg to send reinforcements. Still believing the situation in Fort Fisher was under control and tired of Whiting's demands, Bragg instead dispatched General Alfred H. Colquitt to relieve Whiting and assume command at Fort Fisher. At 9:30 p.m. Colquitt landed at the southern base of the fort just as Lamb, Whiting and the Confederate wounded were being evacuated to Battery Buchanan.

At this point, the Confederate hold on Fort Fisher was untenable. The seaward batteries had been silenced, almost all of the north wall had been captured, and Ames had fortified a bastion within the interior. Terry, however, had concluded to finish the battle that night. Ames, ordered to maintain the offensive, organized a flanking maneuver, sending some of his men to advance outside the land wall, and come up behind the Confederate defenders of the last traverse. Within a few minutes the Confederate defeat was unmistakable. Colquitt and his staff rushed back to their rowboats just moments before Abbott's men seized the wharf. Major Reilly held up a white flag and walked into the Union lines to announce the fort would surrender. Just before 10:00 p.m. Terry rode to Battery Buchanan to receive the official surrender of the fort from Whiting.

The loss of Fort Fisher compromised the safety and usefulness of Wilmington, the Confederacy's last remaining sea port. The South was now cut off from global trade. Many of the military supplies which the Army of Northern Virginia depended upon came through Wilmington; there were no remaining seaports near Virginia that the Confederates could use practically. Potential European recognition of the Confederacy was likely already impossible, but now became entirely unrealistic; the fall of Fort Fisher was "the final nail in the Confederate coffin."[24] A month later, a Union army under General John M. Schofield would move up the Cape Fear River and capture Wilmington.

On January 16, Union celebrations were dampened when the fort's magazine exploded, killing and wounding 200 Union soldiers and Confederate prisoners who were sleeping on the roof of the magazine chamber or nearby. U.S. Navy Ensign Alfred Stow Leighton died in the explosion while in charge of a squad trying to recover bodies from the fort parapet. Although several Union soldiers initially thought Confederate prisoners were responsible, an investigation opened by Terry concluded that unknown Union soldiers (possibly drunken Marines) had entered the magazine with torches and ignited the powder.