 Lincoln , as well as many other leaders and citizens of the northern states , became increasingly impatient with McClellan 's slowness to attack the Confederate forces still massed near Washington . The Union defeat at the minor Battle of Ball 's Bluff near Leesburg in October added to the frustration and indirectly damaged McClellan . In December , the Congress formed a Joint Committee on the Conduct of the War , which became a thorn in the side of many generals throughout the war , accusing them of incompetence and , in some cases , treason . McClellan was called as the first witness on December 23 , but he contracted typhoid fever and could not attend . Instead , his subordinate officers testified , and their candid admissions that they had no knowledge of specific strategies for advancing against the Confederates raised many calls for McClellan 's dismissal . 
