 By the time of the Pennsylvania invasion, Lee had fixed the organizational defects that plagued the army during its early campaigns and the straggling problems of the Maryland Campaign did not repeat themselves.After taking over command in mid-1862, Lee began preparing to lead the Army of Northern Virginia for the first time.However, his aggressiveness to attack the Union led to the loss of many troops especially at the Battle of Antietam, which ended up being a turning point in the war for the Union.