This book is a historical analysis of Major General Joseph J. Reynolds and his division during the Battle of Chickamauga. Chickamauga was the division's first major engagement. Arriving at the battlefield the first day, amidst a fierce Confederate offensive, the division was separated into brigades and regiments. The various units were piecemealed into battle, operating independently of their division commander's control. Division experiences included a desperate charge and the crushing route of an entire brigade. On the second day, the division withstood an initial Confederate onslaught in which the Union line was cut in half. After an attack south of the division's position, the division was forced back, and eventually ordered to withdraw. The day ended with another charge, attacking a threat to the retreating Union army. The division's performance varied during the two-day battle, its reputation neither enhanced or scorned. General Reynolds did not distinguish himself at Chickamauga. Although not a subject of official inquiry, he was never again to command troops in the Civil War. This study analyzes Reynolds and his division at the Battle of Chickamauga and draws conclusions as to the proximate causes of the performance. These causes include division disposition, division control, and a focus on Reynolds' leadership and decisions.