It was not until the spring of 1865 that Gen. Ulysses S. Grant made troops available to Maj. Gen. E. R. S. Canby to commence the Mobile Campaign. Their strategy was to attack Mobile from the eastern shore of Mobile Bay, defusing the protective forts of Spanish Fort and Blakely, 4 miles north, on the east side of the Tensaw River. The next steps toward Mobile were to knock down the marshland batteries of Fort Huger and Fort Tracy, then move across the Tensaw and Mobile Rivers into the city. Maj. Gen. William T. Sherman suggested this easterly route in a letter to Maj. Gen. E.R.S. Canby.
On its western side Mobile was surrounded by 3 lines of fortifications mounting 300 heavy artillery pieces. Water approaches to Mobile were defended by a series of underwater obstructions and island and shore batteries on the east. It was said to be the most heavily fortified city in the Confederacy.
After the disastrous defeat of the Lt. Gen. John B. Hood's Army of Tennessee in the fall of 1864, a remnant of that army was sent to strengthen the Mobile defenses increasing its garrison to almost 10,000 troops. Commanding the Confederate District of the Gulf from Mobile was Maj. Gen. Dabney H. Maury.
On March 17-18, Maj. Gen. E.R.S. Canby's troops of the XVI and XII Corps moved down the east and west shores of Mobile Bay driving Confederates into their defenses at Spanish Fort, opposite the bay from Mobile, and Fort Blakely, northeast of Mobile on the east bank of the Appalachee River. The movement of the XVI Corps down the western bay shore was a diversion. After 2 days, they doubled back and joined XVI Corps troops pressing Fort Blakely and Spanish Fort. Soon, 13,000 Union troops arrived from Pensacola, Florida and by April 1, the Federals had invested Spanish Fort and were within 700 yards of the wall.
After the fall of Spanish Fort, Canby was allowed to turn his force of 45,000 men on Fort Blakely and beseige its garrison of about 4,000 men, commanded by Brig. Gen. St. John R. Liddell.
Liddell's men had been under seige for 6 days when Union sappers' assault trench lines reached a point within 500 yards of the Confederate defenses. The remaining ground to Fort Blakely's walls was covered with obstructions and torpedoes detonated by trip wires. Sniping had been relentless since the seige's beginning.
Canby’s movement against Mobile was a 2-pronged attack. One column was to advance from the lower part of Mobile Bay to invest Spanish Fort. The second column was to progress from Pensacola and center their efforts on Fort Blakely.
Union troops of the first column were assembled by Canby at Dauphin Island to the west and to Mobile Point on the east of the entrance to Mobile Bay. These forces moved in a 32,000-man column from Fort Gaines by steamboats and over land from Fort Morgan to Fish River in lower Baldwin County.
On March 20, the second column of 13,000 Union soldiers, commanded by Brig. Gen. Frederick Steele, moved out from Pensacola on March 20 with instructions to take Fort Blakely from the rear. It moved northward, deceptively, to appear as if heading towards Montgomery Alabama. At the railroad track at Pollard, Alabama, 50 miles north of Pensacola, it turned west towards the Tensaw River and then moved south to invest Fort Blakely.
On April 1, a Union cavalry brigade from the Pensacola column overran an outpost of Confederate infantry at Fort Blakeley in the afternoon.
On April 2, heavy skirmishing commenced as the Union infantry and light artillery moved into position opposite the Blakely fortifications.
Fort Blakely was a formidable entrenchment built of 9 connected earthen artillery redoubts mounting 41 artillery pieces. It was protected by several iron clad vessels of the Confederate Navy.
On April 9, Canby decided to try a general assault at 6:00 P.M. At the appointed hour, 16,000 Union troops leaped from trenches and rushed the Confederates; 37 Union field pieces and 57 seige guns opened on the ground ahead of the charging troops. The Union troops attacked simultaneously the 3 miles of Fort Blakely's breastworks. Liddell's men poured out a heavy small-arms fire but were crushed by artillery and a force of numbers. Assaulting Federals routed Fort Blakely's garrison within an hour. Some Confederates dispersed into nearby woods; others ran for the river landing, where they were trapped. From Fort Blakely, some 3,400 soldiers were taken as prisoners of war to Ship Island. The fall of Fort Blakely signaled to Maury in Mobile to begin evacuation of the remaining Confederate troops in the city.
On April 12, Mobile's mayor, R.H. Slough, surrendered the city to Canby's subordinate, Maj. Gen. Gordon Granger. Mobile was declared an open city and the remaining Confederate garrison retreated with the intention of joining the remains of the Army of Tennessee, then in North Carolina. The surrender of the Army of Tennessee to Sherman on April 26 prevented that option and surrender of the Mobile garrison took place on May 5 in Citronelle, Alabama.
This small force out of Mobile was the last Confederate army to surrender east of the Mississippi River. The surrender of the Confederate forces in Texas took place later in June of 1865. Harper’s Weekly of May 27, reporting on the Battle of Fort Blakely stated, “Probably the last charge of this war, it was as gallant as any on record.”
The fighting at Fort Blakely was the last infantry combat, combined-force battle of the war. Gen. Robert E. Lee's Confederates were surrendered the day the fort fell. African-American forces played a major role in the successful Union assault.
It has long been accepted by the news media and general public that the Civil War ended on April 9, 1865, with the surrender of Gen. Robert E. Lee’s Army of Northern Virginia to Grant.
The Battle of Blakely was the last major battle of the Civil War occurring 6 hours after Lee surrendered at Appomattox.