 Initially, McClellan was somewhat successful against General Joseph E. Johnston, but the emergence of General Robert E. Lee to command the Army of Northern Virginia turned the subsequent Seven Days Battles into a partial Union defeat.However, historians note that Lee's victory was in many ways pyrrhic as he failed to destroy the Army of the Potomac and suffered a bloody repulse at Malvern Hill.General McClellan and President Abraham Lincoln developed a mutual distrust, and McClellan was privately derisive of his commander-in-chief.