These facts undoubtedly created a disparity between the two contending armies, which had not existed during the earlier part of the war. The immigrants and the purchased substitutes who joined the Federal armies after the campaigns of 1862 were over, were not morally the equals of the native or long naturalized Americans who had fought so heroically around Richmond, at the second battle of Manassas, at Sharpsburg, and at Shiloh. For this as well as for the other reasons indicated, the North had need of larger numbers than the South, in order to carry the war to success. The Confederates now held a smaller section of the Mississippi than before, but they held that more strongly. A general of capacity, after Shiloh, might easily have wrested its possession from them, as General Grant has pointed out. Under a general incapacity, nothing was done to that end and the Confederates, thus favored by Federal neglect, had so far fortified their strongholds that the dislodgment which would have been easy in the spring could now be accomplished only by one of the severest, bloodiest and most perilous campaigns of the war. Thus all that had been gained above or below, towards the reconquest of the Mississippi, had gone for next to naught. For the possession of its mouth on the one hand, and the control of its upper reaches on the other, meant nothing so long as the Confederates held Vicksburg and Port Hudson, thus obstructing a river whose sole value was as a highway. In Virginia the Southern arms had been successful in an extraordinary degree. McClellan's splendid army of 120,000 men had been broken and beaten back from the very gates of Richmond, and sent hurriedly northward to defend the National capital itself against threatened capture. Pope, at the head of an army quite equal to any that the Confederates could muster, had been outmaneuvered, outfought and overthrown at Manassas, and hurled back upon the defenses of Washington as a needed refuge. Lee had invaded Maryland, his cavalry amusing themselves by unopposed marches into Pennsylvania. Finally Burnside's attempt at Fredericksburg with an army overwhelming in its numbers, had resulted in fearfully bloody failure.