On 31 December the regiment left Lebanon and marched through Columbia to the field of active operations, moving east to stop the ongoing Confederate invasion of eastern Kentucky.
On Monday, January, 20, the 10th and the 14th Ohio were the first troops into the hastily evacuated Confederate fortifications where they captured a dozen pieces of artillery and large amounts of arms and equipment.
[8][9] It accompanied an expedition up the Tennessee river on transports to Chickasaw, where the troops landed and penetrated the country to destroy a railroad bridge east of Corinth and near Iuka, which was successfully done.
It also crossed the river at Eastport, and marched with trains to Florence, AL. On Friday, July 25, two companies (A and H) were posted to guard Courtland bridge, and while there a large force of Confederate cavalry under Gen. Armstrong fell upon them and captured them.
Several captured letters from Confederate soldiers boasted that the Yankees would be given the slip (Maj. Gen William Rosecrans was impressed with Sheridan's foray and recommended him for promotion to brigadier general).
Armaments were a wide variety with many smoothbore muskets still in the use, morale was low, some units were unpaid for six months,[28] it had many incompetent officers, some cavalry were still unhorsed and unarmed, and mail delivery was poor.
[38] As a member of the Army of the Cumberland, the 10th would spend 1863 in Eastern Tennessee and Georgia as part of the U.S. plan to liberate the region and control the important rail hub of Chattanooga to greatly complicate the Confederacy's logistical support to their war effort.
[40] The Tullahoma campaign was marked by rapid movement by the Army of the Cumberland facilitated by its increased cavalry and added mounted infantry such as Wilder's Lightning Brigade despite heavy rains that muddied the roads.
As such, the XIV Corp advance was so slowed by the rains that the 10th and its brigade arrived at the gap on 25 June in the afternoon and were ordered through to Garrison's Creek ten miles to the south to turn the Rebel left flank.
This time, they were relieved in the line by Johnson's 2nd Division of McCook's XX Corps, and received direction from Brannan to withdraw west of La Fayette Road at the foot of Horseshoe Ridge to resupply.
Initially alerted, the 10th were kept below horseshoe ridge as Thomas chose the 92nd Illinois Mounted Infantry which had been detached from Wilder's Lightning Brigade in Reynolds'4th Division to act as a Corps quick reaction reserve.
[63] The column under command of MGEN Hood poured through and caught Federal troops out of position on the march north from McCook's XX Corps to reinforce Thomas.
[65] While the Army of the Cumberland's right was collapsing and reeling back along the roads toward Chattanooga, Brannan kept a cool head and faced his division southeast at the foot of Horseshoe Ridge.
While Sheffield continued west pursuing the broken Federals, Benning turned to face Croxton's brigade, and attacked north across the field to add to the weight of Robertson.
The remainder of the Army of the Cumberland had dissolved to the point that the only cohesive, intact unit remaining south of the 10th and the rest of Thomas' command was Wilder's which had seriously mauled the left flank of Longstreet's attack column due to the firepower.
Bragg was not able to mount the kind of pursuit due to his army's exhaustion, the fact that Longstreet's divisions had arrived by rail without wagons to transport their supplies, and the high loss of the artillery horses injured or killed during the battle.
[77] Due to this situation, all supplies for Chattanooga had to be hauled by the Anderson road, a circuitous route, north of the river, over mountainous country, increasing the distance to over sixty miles.
This loss in wagons, with the roads becoming almost impassable by reason of the heavy rains and the growing weakness of the animals, lessened daily the amount of supplies brought into the town, so that suddenly, the long term survival of the horses and mules was in serious doubt.
To supply an army some forty thousand strong, by wagon transportation over rough mountain roads a distance of sixty miles, Bragg thought was an impossibility, and that unless other lines were opened up, the city would be his at minimum cost.
[86] Even before the Union defeat, Maj. Gen. Ulysses S. Grant had been ordered to send his available force to assist Rosecrans, and it departed under his chief subordinate, Maj. Gen. William T. Sherman, from Vicksburg, Mississippi.
[101] Hooker, while his force passed through Lookout Valley on October 28, detached Geary's division at Wauhatchie Station, a stop on the Nashville and Chattanooga Railroad, to protect the line of communications to the southwest as well as the road west to Kelley's Ferry.
[106] Geary continued to hold fast, though running low on ammunition, and just as Bratton began to sense victory, he received a note to retreat since Howard's relief force was arriving in his rear.
When he asked permission from Davis to do so, Bragg suggested sending Longstreet and his corps of 15,000 troops and Wheeler's 5,000 cavalry to Knoxville to attack Burnside there and threaten Grant's left flank.
For his part, Burnside, confident in his ability to defend himself, suggested that he pull all his forces between Chattanooga and Knoxville back to his fortifications in the city to draw Longstreet further away from his railhead at Loudon[note 19] to make it more difficult for him to return to Bragg when Grant attacked.
The Army of the Cumberland would play a supporting role in the upcoming actions with Sherman's Vicksburg veterans delivering a hammer blow on Patrick Cleburne's division on Bragg's right at the northern end of Missionary Ridge.
[132] Bragg weakened his position further on November 22, ordering Cleburne to withdraw his and Buckner's divisions from the line and march to Chickamauga Station, for railroad transport to Knoxville, removing 11,000 more men from the defense of Chattanooga.
[133] On Monday, November 23, the 10th Kentucky saw columns of Cleburne's and Buckner's men marching away from Missionary Ridge and also heard claims from Confederate deserters that the entire army was going to retreat.
Grant was afraid that Bragg would escape his grasp and that a reinforced Longstreet would become a viable threat to Burnside and Unionist East Tennessee, so he decided to disrupt the movement.
Thomas sent Wood's3rd Division of Granger's IV Corps to advance in a reconnaissance in force, instructing him to avoid an engagement with the enemy and return to his fortifications when the strength of the Confederate line was revealed.
After receiving assurances from Sherman that he could proceed with three divisions, Grant decided to revive the previously rejected plan for an attack on Lookout Mountain and reassigned Osterhaus to Hooker's command.