After Iuka, Grant established his headquarters at Jackson, Tennessee, a central location to communicate with his commands at Corinth and Memphis. Rosecrans returned to Corinth. Maj. Gen. Edward Ord, whose three divisions of Grant's Army of the Tennessee had been accidentally unengaged at Iuka, move to Bolivar, Tennessee, northwest of Corinth, to join with Maj. Gen. Stephen A. Hurlbut. Thus, Grant's forces in the immediate vicinity consisted of 12,000 men at Bolivar, Rosecrans's 23,000 at Corinth, Maj. Gen. William T. Sherman's 7,000 at Memphis, and another 6,000 as a general reserve at Jackson.
Price's army marched to Ripley where it joined Van Dorn on September 28. Van Dorn was senior officer and took command of the combined force, numbering about 22,000 men. They marched to Pocahontas, Tennessee, on October 1, on the Memphis and Charleston Railroad. From this point they had a number of opportunities for further moves and Grant was uncertain about their intentions. When they bivouacked on October 2 at Chewalla, Grant became certain that Corinth was the target. The Confederates hoped to seize Corinth from an unexpected direction, isolating Rosecrans from reinforcements, and then sweep into Middle Tennessee. Grant sent word to Rosecrans to be prepared for an attack, at the same time directing Hurlbut to keep an eye on the enemy and strike him on the flank if a favorable opportunity offered. But Rosecrans was already prepared.
Along the north and east sides of Corinth, about two miles from the town, was a line of entrenchments, extending from the Chewalla Road on the northwest to the Mobile and Ohio Railroad on the south, that had been constructed by Confederate General P.G.T. Beauregard's army before they evacuated the town in May. These lines were too extensive for Rosecrans's 23,000 men to defend, so with the approval of Grant, Rosecrans modified the lines to emphasize the defense of the town and the ammunition magazines near the junction of the two railroads. The inner line of redoubts, closer to the town, called the Halleck Line, were much more substantial. A number of formidable named batteries, guns positioned in strong earthwork defenses, were part of the inner line: Batteries Robinett, Williams, Phillips, Tannrath, and Lothrop, in the area known as College Hill. They were connected by breastworks, and during the last four days of September these works had been strengthened and the trees in the vicinity of the centrally placed Battery Robinett had been felled to form an abatis. Rosecrans's plan was to absorb the expected Confederate advance with a skirmish line at the old Confederate entrenchments and to then meet the bulk of the Confederate attack with his main force along the Halleck Line, about a mile from the center of town. His final stand would be made around the batteries on College Hill. His men were provided with three days' rations and 100 rounds of ammunition. Van Dorn was not aware of the strength of his opponent, who had prudently called in two reinforcing divisions from the Army of the Tennessee, and the difficulty of assaulting these prepared positions.
On October 3, three of Rosecrans's divisions advanced into the old Confederate rifle pits north and northwest of town: McKean on the left, Davies in the center, and Hamilton on the right. Stanley's division was held in reserve south of town. Van Dorn began his assault at 10 a.m. with Lovell's division attacking McArthur's brigade (McKean's division, on the Union left) from three sides. Van Dorn's plan was a double envelopment, in which Lovell would open the fight, in the hope that Rosecrans would weaken his right to reinforce McKean, at which time Price would make the main assault against the Federal right and enter the works. Lovell made a determined attack on Oliver and as soon as he became engaged Maury opened the fight with Davies's left. McArthur quickly moved four regiments to Oliver's support and at the same time Davies advanced his line to the entrenchments. These movements left a gap between Davies and McKean, through which the Confederates forced their way about 1:30 p.m., and the whole Union line fell back to within half a mile of the redoubts, leaving two pieces of artillery in the hands of the Confederates.
During this part of the action Gen. Hackleman was killed and Gen. Oglesby (the future governor of Illinois) seriously wounded, shot through the lungs. About 3 p.m. Hamilton was ordered to change front and attack the Confederates on the left flank, but through a misunderstanding of the order and the unmasking of a force on Buford's front, so much time was lost that it was sunset before the division was in position for the movement, and it had to be abandoned. Van Dorn in his report says: "One hour more of daylight and victory would have soothed our grief for the loss of the gallant dead who sleep on that lost but not dishonored field." But one hour more of daylight would have hurled Hamilton's as-yet unengaged brigades on the Confederate's left and rear, which would in all probability have driven Van Dorn from the field and made the second day's battle unnecessary.
So far the advantage had been with the Confederates. Rosecrans had been driven back at all points, and night found his entire army except pickets inside the redoubts. Both sides had been exhausted from the fighting. The weather had been hot (high of 94° F) and water was scarce, causing many men to nearly faint from their exertions. During the night the Confederates slept within 600 yards of the Union works, and Van Dorn readjusted his lines for the attack the next day. He abandoned his sophisticated plans for double envelopments. Historian Shelby Foote wrote, "His blood was up; it was Rosecrans he was after, and he was after him in the harshest, most straightforward way imaginable. Today he would depend not on deception to complete the destruction begun the day before, but on the rapid point-blank fire of his guns and the naked valor of his infantry."
On October 4, At 4:30 a.m. the Confederates opened up on the Union inner line of entrenchments with a six-gun battery, which kept up its bombardment until after sunrise. When the guns fell silent, the Federal troops prepared themselves to resist an attack. But the attack was slow in coming. Van Dorn had directed Hébert to begin the engagement at daylight and the artillery fire was merely preliminary to enable Hébert to get into position for the assault.
At 7 a.m., Hébert sent word to Van Dorn that he was too ill to lead his division, and Brig. Gen. Martin E. Green was ordered to assume command and advance at once. Nearly two hours more elapsed before Green moved to the attack, with four brigades in echelon, until he occupied a position in the woods north of town. There he formed in line, facing south, and made a charge on Battery Powell with the brigades of Gates and McLain (replacing Martin), while the brigades of Moore (replacing Green) and Colbert attacked Hamilton's line. The assault on the battery was successful, capturing the guns and scattering the troops from Illinois and Iowa. Hamilton repulsed the attack on his position and then sent a portion of his command to the assistance of Davies, who rallied his men, drove the Confederates out of the battery, and recaptured the guns. Maury had been engaged sometime before this. As soon as he heard the firing on his left, he knew that Davies and Hamilton would be kept too busy to interfere with his movements, and gave the order for his division to move straight toward the town. His right encountered a stubborn resistance at about 11 a.m. from Battery Robinett, a three-gun redan protected by a five-foot ditch, where fierce hand-to-hand combat ensued, and he was forced to retire with heavy losses from arguably the hottest action of the two-day battle. Col. William P. Rogers of the 2nd Texas, a Mexican-American War comrade of President Jefferson Davis, was among those killed in the charge. Lawrence Sullivan Ross was mistakenly reported killed with Rogers.
Phifer's brigade on the left met with better success, driving back Davies's left flank and entering the town. But their triumph was short-lived, as part of Sullivan's brigade, held as a reserve on Hamilton's left, charged on the Confederates, who were thrown into confusion in the narrow streets, and as they fell back came within range of batteries on both flanks of the Union army, the cross-fire utterly routing them. Cabell's brigade of Maury's division was sent to reinforce the troops that had captured Battery Powell, but before they arrived, Davies and Hamilton had recaptured it and as Cabell advanced against it he was met by a murderous fire that caused his men to retreat.
Meanwhile Lovell had been skirmishing with the Union left in the vicinity of Battery Phillips, in preparation for a general advance. Before his arrangements were complete he was ordered to send a brigade to Maury's assistance, and soon afterward received orders to place his command so as to cover the retreat of the army. At 4 p.m., reinforcements from Grant under the command of Brig. Gen. James B. McPherson arrived from Jackson. But the battle of Corinth had effectively been over since 1 p.m. and the Confederates were in full retreat.
Rosecrans's army lost 355 killed, 1,841 wounded, and 324 missing at Corinth; Van Dorn's losses were 473 killed, 1,997 wounded, and 1,763 captured or missing.
Rosecrans's performance immediately after the battle was lackluster. Grant had given him specific orders to pursue Van Dorn without delay, but he did not begin his march until the morning of October 5, explaining that his troops needed rest and the thicketed country made progress difficult by day and impossible by night. At 1 p.m. on October 4, when pursuit would have been most effective, Rosecrans rode along his line to deny in person a rumor that he had been slain. At Battery Robinett he dismounted, bared his head, and told his soldiers, "I stand in the presence of brave men, and I take my hat off to you."
Grant wrote disgustedly, "Two or three hours of pursuit on the day of the battle without anything except what the men carried on their persons, would have been worth more than any pursuit commenced the next day could have possibly been." Rosecrans returned to Corinth to find that he was a hero in the Northern press. He was soon ordered to Cincinnati, where he was given command of the Army of the Ohio (to be renamed the Army of the Cumberland), replacing Don Carlos Buell, who had similarly failed to pursue retreating Confederates from the Battle of Perryville.
Although his army had been badly mauled, Van Dorn escaped completely, evading Union troops sent by Grant later on October 5 at the Battle of Hatchie's Bridge, and marching to Holly Springs, Mississippi. He attributed his defeat to the failure of Hébert to open the second-day engagement on time, but nevertheless he was replaced by Maj. Gen. John C. Pemberton immediately after the battle. There were widespread outcries of indignation throughout the South over the senseless casualties at Corinth. Van Dorn requested a court of inquiry to answer charges that he had been drunk on duty at Corinth and that he had neglected his wounded on the retreat. The court cleared him of all blame by unanimous decision.
Van Dorn's combined Confederate Army of Tennessee was organized as follows:
Price's Corps, also known as the Army of the West, with two divisions commanded by Brig. Gen. Louis Hébert (brigades of Brig. Gen. Martin E. Green and Colonels Elijah Gates, W. Bruce Colbert, and John D. Martin) and Brig. Gen. Dabney H. Maury (brigades of Brig. Gens. John C. Moore and William L. Cabell, and Col. Charles W. Phifer).
The 1st Division of the District of the Mississippi, commanded by Maj. Gen. Mansfield Lovell, with the brigades of Brig. Gens. Albert Rust, John B. Villepigue, John S. Boland, and a cavalry brigade commanded by Col. William H. Jackson, and Major St. L. Dupiere's Louisiana Zouave battalion.
Rosecrans's Army of the Mississippi was organized as follows:
Division of Brig. Gen. David S. Stanley included the brigades of Cols. John W. Fuller and Joseph A. Mower.
Division of Brig. Gen. Charles S. Hamilton included the brigades of Brig. Gens. Napoleon B. Buford and Jeremiah C. Sullivan.
Cavalry division of Col. John K. Mizner included the brigades of Cols. Edward Hatch and Albert L. Lee.
A division on loan from the Army of the Tennessee, commanded by Brig. Gen. Thomas A. Davies, included the brigades of Brig. Gens. Pleasant A. Hackleman and Richard J. Oglesby, and Col. Silas D. Baldwin.
A second division on loan, commanded by Brig. Gen. Thomas J. McKean, included the brigades of Brig. Gen. John McArthur and Cols. John M. Oliver and Marcellus M. Crocker.