When Vice-Admiral Farragut left the West Gulf squadron in the autumn of 1864, the command devolved on Commodore James S. Palmer, senior officer on the station. That officer continued operations until the arrival of Admiral Farragut’s successor, Acting-Rear-Admiral Thatcher. The resumption of offensive operations against the city of Mobile, under the direction of Major-General Canby, was not determined upon until early in January, when Acting-Rear-Admiral Thatcher was ordered to proceed immediately to New Orleans, in order to cooperate with the military commander.

The force placed under Acting-Rear-Admiral Thatcher was increased by light-draught iron-clads detached from the Mississippi squadron for service in Mobile Bay. A joint movement by land and water was arranged and carried into execution. Indications that the rebels were about to evacuate the city led to a naval reconnoissance in force, to ascertain the facts, on the 11th of March, with five monitors, in as close proximity as the shallow water and obstructions would permit. This movement drew from the insurgents such a fire as to place beyond doubt that those defences were still intact.

The principal defence of Mobile was Spanish Fort, an irregular bastioned work of very ancient structure, connected with fortifications five miles in length commencing at D’Olive’s creek, and running to Minetta bay. Beyond Spanish Fort, to the left, on the opposite shore of Minetta bay, is Fort Alexis, mounting heavy guns. Forts Huger, Bradley, Tracy, Battery Gladden, Spanish River battery, Blakely, and other rebel defences frowned defiantly on the Federal army from the land side.

From September, 1864, to March, 1865, important movements of the armies of the Nation in distant States deterred the Government from sending a sufficient military force for the reduction of Mobile, which was garrisoned during that time by about fifteen thousand troops under General Maury.

After the breaking up of Hood’s army by Thomas, and the successful march of Sherman through South Carolina, the corps of A. J. Smith and General Steele were sent to reinforce General Canby, and steps were taken to insure the capture of Mobile. An army of forty thousand men soon invested the city on the land side, while the powerful fleet closed up the waters, and prepared for the perilous attack.

The Sixteenth corps, Major-General A. J. Smith commanding, moved from Fort Gaines by water to Fisher’s river; the Thirteenth corps, under Major-General Gordon Granger, moved from Fort Morgan and joined the Sixteenth corps on Fisher’s river.

The troops were landed on the 21st of March on the left bank of Fisher’s river, about seventeen miles from its junction with the bay, and advanced as rapidly as the condition of the road would permit, while the naval vessels shelled the woods and kept open communication by signals with General Canby for cooperation.

On the 27th of March, an assault on Spanish Fort was made by General Canby’s troops, and simultaneously a portion of the fleet crossed Blakely river bar, an extremely dangerous undertaking, owing to shallow water, and the number of torpedoes with which that portion of the bay was filled. The rebels doubtless believed that the naval vessels were not able to cross the bar of Blakely river; and even if successful in crossing, that it was in their power to destroy the fleet by their marsh batteries and the innumerable torpedoes with which the river was filled. They did succeed in sinking two of the monitors, the Milwaukee and the Osage, and four wooden gunboats at the entrance of Blakely river, by these submarine implements of destruction, although the river had been thoroughly dragged, and many torpedoes were removed before the vessels went over the bar.

By the 3rd of April, Spanish Fort and Fort Alexis had been completely invested by the troops, and during the night of the 8th and morning of the 9th they were, after a short but severe bombardment, captured, and with them from sixteen hundred to two thousand men, with sixteen heavy guns. With the key to Mobile thus secured, the other works of importance, Batteries Tracy and Huger, were within easy reach, and on the evening of the 11th they were evacuated.

At two o’clock on the morning of April 9th, General Canby’s troops entered the intrenchments. General Canby’s report, the next morning, said:

“Spanish Fort and its dependencies were captured last night. We have twenty-five officers, and five hundred and twenty-eight enlisted men prisoners, and have taken five mortars, and twenty-five guns. The major part of the garrison escaped by water. Blakely is already invested and will be assaulted to-day.”

On the 12th, the troops were convoyed to the west side of the city for the purpose of an attack, and the fleet gained a suitable position for performing its share of this work, but it was soon ascertained that the city was at the mercy of the Union arms, all the remaining defences having been abandoned. A formal surrender was, therefore, demanded by General Granger, and Acting-Rear-Admiral Thatcher, which was complied with, and possession was taken of the city. The works which environed Mobile were of immense strength and extent. Nearly four hundred guns were captured, some of them new and of the heaviest calibre.

The rebel army, on evacuating the city, retreated up the Tombigbee. Preparations to follow and capture them were far advanced, when, on the 4th of May, propositions were received from Commander Farrand, commanding the rebel naval forces in the waters of Alabama, to surrender all the vessels, officers, men, and property yet afloat and under blockade on the Tombigbee. The basis of the terms of surrender, being the same as those of General Lee, were accepted. On the 10th of May the formal surrender took place, and the insurgent navy ceased to be an organization. Four vessels were surrendered, and one hundred and twelve officers, two hundred and eighty-five men and twenty-four marines were paroled and permitted to return to their homes.

Sabine Pass and Galveston, the only remaining rebel fortified points on the Gulf coast, soon capitulated.