Two Things

Since the fall of Corinth in May of 1862, the control of the Tennessee River and destruction of General Bragg's army had been primary objectives of Buell's Army of the Ohio.  Buell's failure on both fronts had led to his dismissal and the subsequent reorganization of the Union's western armies.  In the fall of that year, The Army of the Cumberland was formed and tasked with these objectives, it's leadership handed to General William S. Rosecrans.  It was apparent at that time the the War Department's patience had been exhausted, and results were expected in short order.

Rosecrans assumed command in October of 1862 and challenged  Bragg near Murfresboro, Tennessee at the Battle of Stone's River that New Year's Eve and the first two days of 1863.  Despite having one of the highest casualty rates of all battles in this awful, bloody war, the results were militarily inconclusive. Rosecrans garnered support, however,  for having repelled two Confederate assaults and causing Bragg to withdraw to Tullahoma.

General Rosecrans' plan for securing middle Tennessee is nearing it's completion in August of 1863, after yet another reorganization and reinforcements that included the Seventeenth Kentucky Volunteer Infantry. The XIV Corps was separated from Rosecrans' Army of the Cumberland.  It's center wing, now designated as the XIV Corps, remained under General George H. Thomas,  it's right wing the XX Corps under Alexander McCook and it's left wing the XXI Corps under Thomas L. Crittenden.

Nashville has now been secured as well as the surrounding high ground, known as the Highland Rim.  It has been a long summer campaign which would be characterized as "advance and hold" in today's jargon.  In it's final contribution to the Tullahoma Campaign, Crittenden's XXI Corps, containing the Seventeenth Kentucky, was ordered to McMinnville, Warren County, Tennessee where it remained, performing various patrol assignments throughout the months of July and August..

McMinnville sits along the southeastern limit of the Highland Rim and the base of the Cumberland Plateau, strategically located about 35 miles south of Cookeville and 70 miles northwest of Chattanooga, Tennessee. These two months were a relatively quiet time for the Seventeenth.  Bragg had taken refuge in the vicinity of the small but critical city of Chattanooga, which had a pre-war population of about 1,500 citizens.  This population more than doubled throughout the summer as wounded Confederate soldiers were evacuated from Nashville hospitals.  

Transportation was the primary generator of Chattanooga's economy thanks to it's location on the eastern bank of the Tennessee River at  Moccasin Bend, where the Tennessee changes its southerly course and flows to the east across northern Georgia and Alabama.  It was also the northern terminus of the Western and Atlantic Railroad, thus being connected by rail to Atlanta and thence to Savannah, Georgia.  It was also in Chattanooga that the Western and Atlantic met the Memphis and Charleston Railroad, thereby connecting two of the South's busiest ports by rail to the Mississippi River.  With New Orleans secured, Chattanooga was vital to the Union's control of the expanse of Confederate States west of the Cumberlands.