The Battle of Stones River was part of a grand Union offensive
One of the most remarkable facts about the battle of Stones River is that it was part of a grand Union offensive. Following the Battle of Perryville on October 8, 1862, in Kentucky, Confederate general Braxton Bragg's Force of Mississippi withdrew to Harrodsburg, Kentucky, where it was joined on October 10 by Maj. Gen. Edmund Kirby Smith's 10,000-man army. Despite having 38,000 veteran soldiers in his newly merged force, Bragg made no attempt to retake the initiative. The Union commander at Perryville, Maj. Gen. Don Carlos Buell exhibited a similar lack of aggression by choosing not to attack Bragg.
Maj. Gen. William S. Rosecrans, who had recently won the engagements of Iuka and Corinth, took the position of Buell on the Union side after President Abraham Lincoln grew impatient with him for his inaction. Washington told Rosecrans that if he did not move firmly against Bragg and seize eastern Tennessee, he too would be dismissed. Rosecrans marched his XIV Corps (which was shortly after dubbed the Army of the Cumberland) to Nashville, Tennessee. Rosecrans, however, took enough time to reorganize, train, and restock his army's forces, especially his cavalry. He didn't start marching after Bragg until the 26th of December.
Abraham Lincoln and General-in-Chief Henry Halleck made the decision to pressure the Confederacy on all fronts in the latter months of 1862. They thought the simultaneous assaults of Ambrose E. Burnside in Virginia, William T. Rosecrans in Tennessee, and Ulysses S. Grant in Mississippi would prevent the Confederates from shifting reinforcements to counter them. While Grant's campaign against Vicksburg faltered and Burnside met with tragedy at Fredericksburg, Rosecrans lamented a shortage of supplies and did not proceed until December 26. Rosecrans' grand strategy worked despite tactical setbacks in the east and west, as Confederate commander Braxton Bragg, in charge of the army in Tennessee, dispatched around one-sixth of his infantry to reinforce Vicksburg on December 16.
