The Confederate Army of Mississippi (almost 45,000) attacked two separate Union Armies (Tennessee and Ohio) that totaled over 65,000.

Losses were very heavy, over 13,000 Union and 10,000 Confederate.

As a result of the fall of Forts Henry and Donelson, Albert Sidney Johnston, the regional commander, was forced to fall back, giving up Kentucky and much of West and Middle Tennessee. He chose Corinth, Mississippi, a major transportation center, as the staging area for an offensive against Grant’s Army of the Tennessee before Buell’s Army of the Ohio could join it. (Part of Johnston’s choice was necessity: with the Union controlling the Tennessee River, he could only mass on one side or the other, he couldn’t shift back and forth.) Johnston pulled his own men out of central Kentucky, and joined Polk’s and Beauregard’s men from western Tennessee with Bragg’s men from Pensacola, Florida.

Johnston’s withdrawal from central Tennessee was a surprise, although a pleasant one, to the Union forces, and it took Grant, with about 40,000 men, some time to mount a southern offensive. He envisioned operating chasing the Confederate armies, realizing that if he defeated the rebel armies, cities would fall later. However, his theater commander, Henry Halleck, thought more in terms of geographical objectives. Their confusion delayed the operation along the Tennessee River. It did mean that Buell’s army (around 50,000) were ordered west, to join Grant’s troops.

Grant’s army was camped (unfortified) at Pittsburg Landing, only 22 miles by road from Corinth. He didn’t have protective detachments out, nor did he have cavalry to screen his position. (He did know the Confederates were massing a force larger than his. Since many of his men were green, most of his energy was directed to drilling them. They were scattered by divisions (some division commanders separated their brigades) through the partly wooded ground. The whole area was sparsely settled, with patches of heavy woods and cleared fields up to 80 acres. There were also a number of creeks and roads splitting the ground into bits and pieces.

Johnston originally planned to move on April 1, but his concentration was slow and it took time to build one army out of four. He was delayed two days and he was tempted to wait longer for Earl Van Dorn to bring 20,000 more men from Arkansas. (Van Dorn was delayed by high water; if Johnston had waited for him to arrive, Grant and Buell would have united as well.) Even that was not the end of the delays in a green army, and having only two roads to march on. They were 9 hours late arriving, 4 PM instead of 7 AM, and had to postpone the attack until the April 6th since there wasn’t enough daylight left on the 5th. There were signs of the impending attack, but the Northern forces ignored them all. Grant telegraphed “I have scarcely the faintest idea of an attack (general one) being made upon us, but will be prepared should such a thing take place.”

Johnston organized his roughly 45,000-man attack in three lines, Hardee’s Corps leading, Bragg’s in the middle, and Polk’s small Corps (with Breckenridge’s division) as the third line. (This had the problem that nobody had their own troops to call forward as a reserve.) At 6 AM the gray line started forward, but got tangled in the woods, so the first and second lines merged and reduced Johnston’s reserve to just the third line. The advance hit the gap between Prentiss’ and Sherman’s divisions and broke through. As early as 7.30 Johnston threw in his third line, Polk to support the left and Breckinridge to the right. Union reinforcements were thrown in, McClernand’s and Hurlbut’s divisions, but at the same time Prentiss’ division collapsed. From his whole division Prentiss rallied about a regiment-worth of men. But he rallied them in a strong position, a battle line at the sunken road later known as the “Hornets Nest.” Badly co-ordinated Confederate attacks one after another were repulsed. Johnston himself led one of the attacks, and was wounded. (He didn’t think it was serious, but he bled to death about 2.30 and Beauregard took command.)

Through the morning and early afternoon the Confederates pressed the Union flanks, using their numerical superiority over Grant’s single Army. Sometimes resistance was fierce, sometimes weak, but the flanks finally gave way, and about 3 PM Bragg led his men in a flank attack which crumpled Hurlbut’s line. Some of his men were cut off when Hardee linked with Bragg; after fierce fighting about 2,200 men finally surrendered.

The prospects for the Union were grim. Thousands of green soldiers had left the ranks individually, or whole units dissolved during withdrawals. They skulked back to the river, finding shelter under the overhanging banks from the risks of battle. But if the Confederates got to the top of the bluffs, the mob of men – hardly soldiers any longer – would have to surrender. Instead, Col. Joseph Webster built an artillery line, 40 to 50 guns, a bare half-mile from the river. Behind the thin line Hurlbut rallied about 4,000 men. Bragg tried to mount an attack, but the Southern forces were exhausted and scattered. Orders got confused and of two brigades available, only Chalmers’ attacked and was bloodily repulsed. It was too late in the day for another attack; Grant’s army had survived.

The night passed with the Confederates in old Union camps, units and men tangled and mixed. Meanwhile Buell’s men were arriving; a division had arrived late on the 6th (suffering only three casualties) and Grant was trying to reorganize his men. By daylight on the 7th the situation was reversed. Union forces outnumbered the Confederates; Johnston’s gamble on fighting the two armies separately had failed.

Grant and Buell had no combined plan, neither took charge (Grant was senior) but their numbers were far superior. Their fresh troops (Buell’s plus Lew Wallace’s division of Grant’s that had been separate from the main army) alone outnumbered the Confederates, and the Southern forces were exhausted and scattered. It was obvious that they could attack with every chance of success.

The Union advance started early, and contact was made about 5:20 AM. Beauregard at first counterattacked – he didn’t know that Buell’s men had arrived. The Union regained the initiative and Southern counterattacks could halt the advance, but never break the Union line. Gradually the Confederates were driven back, but it was not until early afternoon that Beauregard ordered a retreat. Breckinridge commanded a 4,000 man rearguard, with Forrest “between him and the enemy”; there was no pursuit, and the rearguard only pulled back about two miles. Even on the 8th, a Union advance by two divisions was tentative, and stopped when Forrest charged the 4th Illinois Cavalry at Fallen Timbers. The casualties were very heavy, about 13,000 Union losses and 10,000 Confederate. This was the bloodiest battle of the war so far, and caused Grant real problems with state politicians, who complained that he got their constituents killed.

Grant had beaten the Confederates once again. Further bad news was the surrender of Island No. 10 on the Mississippi on the 7th, with 7,000 prisoners and – more important – opening the Mississippi as far as Memphis. The Confederates continued to fall back until launching their mid-August offensive.

Content provided by:
eHistory Staff

Selected sources:
American Battlefield Protection Program, Heritage Preservation Services, National Park Service.