August 5, 1862
Brig. Gen. Thomas Williams, USA
Maj. Gen. John C. Breckinridge, CSA
The Union had a fortified brigade; Breckinridge attacked with a two weak divisions.
Union casualties were a bit under 400, Confederate losses almost 500.
Knowing the Union river garrisons were generally weak, Earl Van Dorn, Confederate commander at Vicksburg, decided to retake Baton Rouge. He knew he couldn't hold it against another gunboat-backed attack, but he would capture the garrison and encourage Louisianans to support the Confederate cause. He sent Breckinridge with a division (and command authority for the expedition) to regain the town. Also scheduled to participate was the pride of the Confederate Navy, the ironclad Arkansas.
Breckinridge's men went south by rail, but with hardly any equipment or supplies beyond their rifles. Short of shoes, food, and artillery, the division was joined by David Ruggles' small infantry division at Camp Moore, east of the city. They had to wait for the Arkansas, and while they waited the underfed men turned sickly, losing about half their strength. Yet the Union garrison was equally diseased, and poorly fortified because they simply didn't really expect a major attack.
Breckinridge moved up in two stages: to the Comite River (10 miles east of town) on August 4, then over the night of August 4-5 into position to attack at dawn. But overnight sentries fired at each other, and the Confederates lost the element of surprise.
At first they drove back each Union unit they encountered, but gradually the attack became disorganized. Brigade commanders were killed or wounded, and with smoke and fog over the battlefield rumors spread ' several times units pulled back because someone heard an order to withdraw. Also, artillery fire from gunboats on both flanks supported the defense and slowed the advance. Still, the Union center was close to collapse ' and then it did break. Only the flanking fire from the gunboats and the determined stand of the 6th Michigan saved the day. The Confederates were exhausted from their night march and the long hours of combat; hungry from days of short rations; thirsty from biting cartridges. Breckinridge pulled back to refresh and reorganize his men, and also to allow the Arkansas to sweep aside the Union gunboats.
But she never arrived: her engines had failed and she couldn't steer; when she plowed into the bank for the last time her crew, exhausted from several days of fixing breakdowns on the 200-mile voyage down river, set her afire. When Breckinridge got the news that she would never arrive he knew he had to break off the attack: he had only a dozen guns, far too few to punch through.
Afterwards the Federal forces used 'contrabands', escaped slaves, to bury the dead and prepare extensive fortifications on a short, strong line. They were not about to be caught unprepared again and have to fight such a near-run battle.