 Carl Sandburg wrote , " McClellan was the man of the hour , pointed to by events , and chosen by an overwhelming weight of public and private opinion . " On July 26 , the day he reached the capital , McClellan was appointed commander of the Military Division of the Potomac , the main Union force responsible for the defense of Washington . On August 20 , several military units in Virginia were consolidated into his department and he immediately formed the Army of the Potomac , with himself as its first commander . He reveled in his newly acquired power and influence : 
