This book will discuss the transformation and creation of the staff of the Army of the Cumberland under the tenure of Major General William S. Rosecrans. The study will suggest that the staff transformation under MG Rosecrans created one of the first truly modern staffs. This book will serve as a case study, illustrating how one commander used his vision of the future to overcome obstacles present in his theater of operations. Additionally, the study will show that after the removal of William S. Rosecrans as Commander of the Army of the Cumberland, the staff infrastructure he envisioned later enabled Sherman to successfully conduct his famous Atlanta Campaign and the subsequent March to the Sea.