Origins — Burnside’s Command
During the American Civil War, there were two Union armies designated as the Army of the Ohio. The first traced its roots to the beginning of hostilities in Kentucky and western Virginia when the War Department was attempting to organize volunteer soldiers in the West. That army existed until October 24, 1862, when General Orders Number 168 created the Department of the Cumberland and designated all the forces within the new department, including the Army of the Ohio, as the 14th Corps.
The second Army of the Ohio came into existence in May 1863, after the War Department placed Major General Ambrose Burnside in charge of the Department of Ohio. Burnside arrived at department headquarters in Cincinnati, Ohio on March 23, 1863 and assumed command two days later. He quickly began concentrating his forces, which were spread across Kentucky. In early April, the army transferred two regiments from the 9th Corps to Burnside’s command. On April 27, 1863, the War Department issued orders, “that troops in Kentucky not belonging to the Ninth Army Corps be organized into the twenty-third army corps . . .” By May 22, 1863, Burnside had completed the consolidation and organization of his forces. He christened the combined 9th and 23rd Corps the Army of the Ohio.
East Tennessee Campaign
Burnside’s first campaign as commander of the Army of the Ohio was the liberation of Eastern Tennessee. On June 2, 1863, he left Cincinnati and proceeded to Lexington, Kentucky. From there, he planned to move against Confederate forces occupying Knoxville, Tennessee, simultaneous to Major-General William S. Rosecrans march on Chattanooga, Tennessee. Just one day later, Burnside delayed the East Tennessee Campaign when he received orders to send the 9th Corps to Mississippi to support Major General Ulysses S. Grant in his operations against Vicksburg.
While awaiting the return of the 9th Corps, Burnside’s troops conducted raids near Knoxville, destroying railroads and communications lines. In July 1863, they took part in the pursuit and capture of Confederate General John Hunt Morgan during his daring cavalry raid into Indiana and Ohio.
Occupation of Knoxville
In early August 1863, Burnside resumed his march on Knoxville from Lexington, planning to reunite with the 9th Corps along the way. The most direct route from Lexington to Knoxville passed through the Cumberland Gap. Because Major General Simon B. Buckner’s Confederate troops blocked his path, Burnside marched two divisions of his army over forty miles of rugged terrain around the Cumberland Gap toward Knoxville. Events occurring in the Chickamauga Campaign had forced Buckner to move most of his army to southern Tennessee, leaving only a token force to defend Knoxville. When Burnside’s cavalry reached Knoxville on September 2, they found it almost unopposed. On September 3, 1863, the citizens of Knoxville warmly received the Army of the Ohio as it occupied the city. Four days later, Burnside marched a brigade back to the Cumberland Gap, where Confederate Brigadier-General John Frazer surrendered on September 9.
Shortly after Burnside secured East Tennessee, Confederate General Braxton Bragg’s Army of Tennessee soundly defeated Major General William Rosecrans’ Army of the Cumberland at the Battle of Chickamauga (September 19–20). Bragg drove Rosecrans’ army out of northern Georgia, back to Chattanooga, Tennessee, and then besieged the city for two months. As the Union situation at Chattanooga worsened, Washington officials ordered Burnside to leave Knoxville and to march south to help lift the siege. Burnside moved toward Chattanooga, but skirmishes with Confederate cavalry along the way slowed his.
Aware of the threat that the Army of the Ohio posed to his investment of Chattanooga, Bragg dispatched General James Longstreet’s command north from Chattanooga to deal with Burnside. Bragg planned on Longstreet being able to drive Burnside away, to re-capture Knoxville, and to return south before Major General Ulysses S. Grant, who had replaced Rosecrans, could attempt a breakout from Chattanooga.
On November 4, 1863, Longstreet departed from Chattanooga by rail with a force of approximately 10,000 infantrymen, supported by 5,000 cavalry troopers. On November 16, he engaged the Army of the Ohio at the Battle of Campbell’s Station, driving the Federals back to their fortifications around Knoxville. With the Federals safely entrenched in Knoxville, Longstreet besieged the city while searching for a weakness in the Union defenses. On November 29, Longstreet ordered an unsuccessful surprise attack against Fort Sanders, northwest of Knoxville.
Before Longstreet could plan another assault, he received news of Bragg’s defeat at the Battle of Missionary Ridge (November 25, 1863). Longstreet lifted his siege of Knoxville and retreated toward Virginia in early December. The Army of the Ohio’s successful East Tennessee Campaign, coupled with the rebuff of Longstreet’s Knoxville Campaign, secured East Tennessee for the Union for the rest of the war.
Near the end of the Knoxville Campaign, Burnside returned to the Eastern Theater with the 9th Corps. On December 9, 1863, Major General John G. Foster replaced Burnside as commander of the Army of the Ohio, which then consisted entirely of the 23rd Corps. Foster commanded the army for only two months until he sustained severe injuries from the fall of his horse.
On February 9, 1864, Major General John M. Schofield assumed command of the Department of the Ohio and of the Army of the Ohio (General Orders, No. 18 (Army of the Ohio)). He commanded the Army of the Ohio throughout Major General William T. Sherman’s Atlanta Campaign (May 7–September 2, 1864).
When General John Bell Hood launched his Franklin-Nashville Campaign (September 18–December 27, 1864) after evacuating Atlanta, Sherman ordered the Army of the Ohio to pursue the desperate Confederate general. Under the overall command of Major General George H. Thomas, Schofield and his men engaged Hood’s army throughout November at the Battle of Columbia (November 24–29, 1864), the Battle of Spring Hill (November 29, 1864), and the Battle of Franklin (November 29, 1864). Schofield inflicted a major defeat upon the Rebels at Franklin before slipping off to join Thomas at Nashville. Two weeks later, the Army of the Ohio took part in the Union victory at the Battle of Nashville (December 15–16, 1864), which ended Hood’s offensive, took the Confederate Army of Tennessee out of the war, and as good as ended the last major campaign west of the Appalachian Mountains.
After the battle of Nashville, Major General Jacob D. Cox temporarily replaced Schofield as commander of the Army of the Ohio from September 14 until October 22, 1864. Schofield returned to command from October 22 until February 2, 1865, when General Grant assigned him to command the Department of North Carolina. When Schofield departed, Major General Jacob D. Cox again assumed command of the Army of the Ohio from February 2 until February 9, 1865.
The Army of the Ohio soon followed Schofield to North Carolina, and Major-General Alfred H. Terry’s 10th Corps joined the mix. Schofield resumed his command on February 9, and the Army of the Ohio served as the center of Sherman’s forces during the Carolinas Campaign (February–April 1865), and was present at Confederate General Joseph E. Johnston’s surrender at Bennett’s Place, near Durham, North Carolina, on April 26, 1865.
On January 17, 1865, the War Department issued General Orders, No. 5 announcing the merger of the Department of the Ohio with the Department of the Cumberland. Schofield turned over his command to Major General George H. Thomas, and the Army of the Ohio ceased to exist.