Union troops placed Corinth under siege, bringing on the Siege of Corinth. While Barrett's battery was present in Corinth during the siege, it did not see fighting. The Confederates eventually abandoned the town during the night of May 29/30. On July 21, Barrett's battery received reinforcements when men from a defunct Louisiana artillery unit known as the Orleans Guard Battery joined the Missourians. After being assigned to the brigade of Colonel Samuel Powell, the strengthened battery participated in the Confederate Heartland Offensive. That campaign was an operation led by Confederate General Braxton Bragg, who had forces in Union-held Kentucky along with Major General Kirby Smith. Control of Kentucky was believed to be vital to the course of the war, as if Kentucky joined the Confederacy, Missouri and Maryland were thought to be likely to do so as well. In early October, elements from both Bragg's army and a Union army commanded by Major General Don Carlos Buell gathered near Perryville, Kentucky, and the Battle of Perryville was fought on October 8.