George B. McClellan

George Brinton McClellan (December 3 1826 –  October 29 1885) was a  major general during the American Civil War. He organized the famous Army of the Potomac and served briefly (November 1861 to March 1862) as the general-in-chief of the Union Army. Early in the war, McClellan played an important role in raising a well-trained and organized army for the Union. However, although McClellan was meticulous in his planning and preparations, these attributes may have hampered his ability to challenge aggressive opponents in a fast-moving battlefield environment. He chronically overestimated the strength of enemy units and was reluctant to apply principles of mass, frequently leaving large portions of his army unengaged at decisive points.
See more at Wikipedia.org...