Late in the summer of 1862, all the principal Confederate armies undertook offensive operations. While the army of Gen. Robert E. Lee invaded Maryland, resulting in the Antietam Campaign, the commands of Maj. Gens. E. Kirby Smith and Braxton Bragg launched a 2-prong thrust into Kentucky. Confederate authorities hoped that these movements into Union territory would result in the recognition of their nation by European countries and would secure supplies and thousands of recruits from the 2 border states.
The Confederate advance into Kentucky began on August 14, when Smith's 10,000 troops departed from Knoxville, Tennessee. Bypassing the Union held Cumberland gap, Smith moved swiftly into the state. On the 30th, the Confederates defeated and captured most of an inexperienced 6,500-man Union garrison at Richmond. Two days later, Smith entered Lexington, then scattered his troops throughout the Lexington-frnkfort-Harrodsburg region with an apparent disregard for Bragg's movements.
Positioned at Chattanooga, Bragg started northward on August 28, 2 weeks after Smith. His 30,000-man Army of Mississippi moved on a parallel route 100 miles west of Smith, entering Kentucky by way of Tompkinsville and Glasgow. On September 17, a Union garrison at Munfordville surrendered to Bragg. A wwek later, the Confederates were located at Bardstown, where they remained until October 3. During this lull, Bragg conferred with Smith at Lexington and installed Richard Hawes as provisional Confederate governer of Kentucky, at Frankfort.
The precense of Confederates in Kentucky, threatening the Ohio River, caused alarm in Louisville and Cincinnati and drew Union Maj. Gen. Don Carlos Buell's Army of the Ohio out of Tennessee. Moving on Chattanooga, Buell reacted slowly at first to Smith's and Bragg's movements, but once their intention became evident, he raced northward to save Louisville. Having received 3 divisions from Maj. gen. Ulysses S. Grant, Buell's army numbered 50,000. On September 29, they reached Louisville, their advance uncontested by Bragg.
The Federals moved against the Confederates on October 1, in 4 parallel columns. The main Union thrust was directed toward Bardstown. Bragg, expecting Buell to move on Frankfort, sent a division to reinforce Smith and concentrated his remaining divisions at Perryville. On the 7th, the vanguard of the Union army struck Bragg's force, now reduced to 16,000. At dawn the next day, a btigade of Brig. Gen. Philip H. Sheridan's division attacked, opening the Battle of Perryville, the only major emgagement of the campaign. A battle of attacks and counterattacks by both sides, Perryville resulted in 4,200 Union and 3,400 Confederate casualties. The Federals eventually held firm and Buell planned an all-out ayyack for the 9th, but Bragg withdrew during the night.
Smith's and Bragg's commands finally united at London, Kentucky. With his men outnumbered, short of supplies, and burdened with sick and wounded, Bragg decided to abandone the campaign. The Confederates, with their hopes of victory and of thousands of volunteers unfullfilled, retreated through Cumberland Gap. Buell pursued timidly, and the final Confederate units reentered Tennessee on the 26th. Kentucky was secured for the remainder of the war. Neither Bragg nor Smith had performed particularly well. Because of his lame pursuit, Buell was relieved of command.