Location: Tennessee
Date: June 7, 1862
Campaign: Confederate Heartland Offensive
In late Spring 1862, the Confederacy split its forces in Tennessee into several small commands in an attempt to complicate Federal operations. The Union had to redistribute its forces to counter the Confederate command structure changes. Maj. Gen. Ormsby Mitchel received orders to go to Huntsville, Alabama, with his division to repair railroads in the area. Soon, he occupied more than 100 miles along the Nashville & Chattanooga and Memphis & Charleston railroads. In May, Mitchel and his men sparred with Maj. Gen. Edmund Kirby Smith's men. After Mitchel received command of all Federal troops between Nashville and Huntsville, on May 29, he ordered Brig. Gen. James Negley with a small division to lead an expedition to capture Chattanooga. This force arrived before Chattanooga on June 7. Negley ordered the 79th Pennsylvania Volunteers out to reconnoiter. It found the Confederates entrenched on the opposite side of the river along the banks and atop Cameron Hill. Negley brought up two artillery batteries to open fire on the Rebel troops and the town and sent infantry to the river bank to act as sharpshooters. The Union bombardment of Chattanooga continued throughout the 7th and until noon on the 8th. The Confederates replied, but it was uncoordinated since the undisciplined gunners were allowed to do as they wished. On June 10, Smith, who had arrived on the 8th, reported that Negley had withdrawn and the Confederate loss was minor. This attack on Chattanooga was a warning that Union troops could mount assaults when they wanted.
Location: Tennessee
Date: August 21, 1863
Campaign: Chickamauga Campaign
On August 16, 1863, Maj. Gen. William S. Rosecrans, commander of the Army of the Cumberland, launched a campaign to take Chattanooga. Col. John T. Wilder's brigade of the Union 4th Division, XIV Army Corps marched to a location northeast of Chattanooga where the Confederates could see them, reinforcing Gen. Braxton Bragg's expectations of a Union attack on the town from that direction. On August 21, Wilder reached the Tennessee River opposite Chattanooga and ordered the 18th Indiana Light Artillery to begin shelling the town. The shells caught many soldiers and civilians in town in church observing a day of prayer and fasting. The bombardment sank two steamers docked at the landing and created a great deal of consternation amongst the Confederates. Continued periodically over the next two weeks, the shelling helped keep Bragg's attention to the northeast while the bulk of Rosecrans's army crossed the Tennessee River well west and south of Chattanooga. When Bragg learned on September 8 that the Union army was in force southwest of the city, he abandoned Chattanooga.
Location: Tennessee
Date: November 23, 1863
Campaign: Chattanooga-Ringgold Campaign
From the last days of September through October 1863, Gen. Braxton Bragg's army laid siege to the Union army under Maj. Gen. William Rosecrans at Chattanooga, cutting off its supplies. On October 17, Maj. Gen. Ulysses S. Grant received command of the Western armies; he moved to reinforce Chattanooga and replaced Rosecrans with Maj. Gen. George Thomas. A new supply line was soon established. Maj. Gen. William T. Sherman arrived with his four divisions in mid-November, and the Federals began offensive operations. On November 23-24, Union forces struck out and captured Orchard Knob and Lookout Mountain. On November 25, Union soldiers assaulted and carried the seemingly impregnable Confederate position on Missionary Ridge. One of the Confederacy's two major armies was routed. The Federals held Chattanooga, the "Gateway to the Lower South," which became the supply and logistics base for Sherman's 1864 Atlanta Campaign.