Col. Morgan, in Murfreesboro with the Army of Tennessee, had learned that the Federals had established strong garrisons at Gallatin, Castalian Springs, and Hartsville, the countryside he was so fond of. At Hartsville with a force of 2,400 men consisting of the 106th and 108th Ohio Infantry, 104th Illinois Infantry, 13th Indiana Artillery, 2nd Indiana Cavalry and a portion of the 11th Kentucky Cavalry was the Federal 39th Brigade with Col. Absalom B. Moore of the 104th Infantry in command. Morgan felt that he could slip through, hit the Yanks quickly and destroy the Hartsville garrison, as his scouts reported the Federal numbers to be about 1,500. As his men were resting at Baird's Mill, Morgan went to Murfreesboro to urge General Braxton Bragg to sanction an attack. After careful consideration helped by Morgan's persistence, Bragg accepted his proposal to cross the Cumberland and hit Hartsville.
After being allowed to select two regiments of Infantry containing some 700 men from Col. Roger W. Hanson's "Kentucky Brigade", he chose the 2nd and 9th Kentucky commanded by his uncle, Col. Thomas H. Hunt, as well as Cobb's Battery. His own men consisted of the 7th, 8th, and 11th Kentucky cavalry, as well as a group of local men commanded by Hartsvillian Col. James D. Bennett, the 9th Tennessee Cavalry. The cavalry was commanded by his brother-in-law Col. Basil W. Duke, including two of Morgan's Kentucky Batteries, Stoner's and Corbett's. Morgan's forces totaled 2,100.
Morgan and his men left Baird's Mill at 10:00 a.m. on December 6, 1862. With the officers only knowing their destination, many rumors began to fly amongst the enlisted men. After arriving in Lebanon around 2:00 p.m. and marching in sleet and snow for eight miles, his men stopped to rest and eat. As they left Lebanon they were told of their destination, Hartsville. Jubilation went throughout the ranks as they continued their long march towards Hartsville, 17 miles away. Arriving at the Cumberland River at 10:00 p.m., they began their crossing of the cold, dark water. Taking longer than expected to cross the swollen Cumberland, Col. Morgan, the Infantry, Artillery, and a small part of the Cavalry crossed at Puryears Bend. Col. Basil W. Duke with the majority of the Cavalry crossed a few miles further down river. Hurrying to meet Morgan at their planned rendezvous point, Duke left a large portion of his men on the south side of the river. With daylight breaking and surprise element almost gone, the Colonel set out without the rest of the Cavalry units, who were still crossing the river. Col. James D. Bennett and his 9th Tennessee Cavalry were sent into town to cut off any escape the Federals might take. Because of the complicated river crossing, Morgan's force was now reduced to 1,300. As they approached the Federal camp, the first Union pickets were captured, but their backups fired shots at the fast-wheeling Confederates and prevented their surprise attack. The cry was heard, "The Rebels are Coming!" Soon it became apparent by the many campfires that the Union numbers were much greater than at first anticipated. Col. Duke exclaimed to Morgan, "You have more work cut out for you than you bargained for!" Morgan answered, "Yes, and you gentlemen must whip and catch these fellows, and cross the river in two hours and a half, or we'll have six thousand more on our backs." Doing just that, Morgan's men, in one hour and fifteen minutes, out-maneuvered and out-fought the enemy; thus, totally defeating a much larger force than their own. Federal losses were 58 killed, 204 wounded, and 1834 captured; total casualties were 2,096. Southern losses were 21 killed, 104 wounded, and 14 missing for a total of 139. Having to hurry to re-cross the Cumberland (for the second time in less than nine hours), Col. Morgan did what most thought could not be done. He successfully transported his men and prisoners back across the chilly water before the Federal reinforcements at Castalian Springs could arrive.
In Nashville, a telegram arrived from the General-In-Chief in Washington D.C. "The President (Abraham Lincoln) directs that you immediately report why an isolated brigade was at Hartsville, and by whose command; and also by whose fault it was to be surprised and captured." Not receiving an appropriate answer, the General-In-Chief fired back, "The most important of the President's inquiries has not been answered. What officer or officers are chargeable with the surprise at Hartsville and deserve punishment?"
Arriving back in Murfreesboro with their captured wagons, arms and much-needed supplies, Morgan and his men were received and honored by the many local citizens along the route as they returned triumphantly as heroes. The victory was a much-needed boost to the morale of the Confederates. Morgan was highly praised by all for this most brilliant achievement and the Confederate Congress congratulated him. Confederate President Jefferson Davis arrived two days later and promoted Morgan to the rank of Brigadier General as the President was presented the captured Federal Infantry colors. General Bragg complimented the entire command and ordered that the name "Hartsville" be inscribed on the banners of all regiments participating.