McClellan, thanks to the bad work of the Confederate staff at the battle of Seven Pines, had now succeeded in securing the passages across the Chickahominy.  But for the present he had given up all idea of an immediate advance.  Two of his army corps had suffered severely, both in men and in moral; the roads were practically impassable for artillery; the bridges over the Chickahominy had been much injured by the floods; and it was imperative to re-establish the communications.  Such is his own explanation of his inactivity; but his official correspondence with the Secretary of War leaves no doubt that his hope of being reinforced by McDowell was a still more potent reason.  During the first three weeks in June he received repeated assurances from Mr. Stanton that large bodies of troops were on their way to join him, and it was for these that he was waiting.  This expectant attitude, due to McDowell’s non-arrival, entailed on him a serious disadvantage.  If he transferred his whole army to the right bank of the Chickahominy, his line of supply, the railway to West Point, would be exposed; and, secondly, when McDowell approached from Fredericksburg, it would be possible for Leo to drive that general back before the Army of the Potomac could give him direct support, or in any case to cut off all communication with him.  McClellan was consequently compelled to retain his right wing north of the river; and indeed in so doing he was only obeying his instructions.  On May 18 Stanton had telegraphed:  “You are instructed to co-operate so as to establish this communication [with McDowell], by extending your right wing north of Richmond.”

The Federal army, then, whilst awaiting the promised reinforcements, was divided into two parts by a stream which another storm might render impassable.  It will thus be seen that Jackson’s operations not only deprived McClellan of the immediate aid of 40,000 men and 100 guns, but placed him in a most embarrassing situation.  “The faulty location of the Union army,” says General Porter, commanding the Fifth Federal Army Corps, “was from the first realised by General McClellan, and became daily an increasing cause of care and anxiety; not the least disturbing element of which was the impossibility of quickly reinforcing his right wing or promptly withdrawing it to the south bank."* (Battles and Leaders volume 2 page 324.)

Seeing that the Confederates were no more than 60,000 strong, while the invading army mustered 100,000, it would seem that the knot should have been cut by an immediate attack on the Richmond lines.  But McClellan, who had been United States Commissioner in the Crimea, knew something of the strength of earthworks; and moreover, although the comparatively feeble numbers developed by the Confederates at Seven Pines should have enlightened him, he still believed that his enemy’s army was far larger than his own.  So, notwithstanding his danger, he preferred to postpone his advance till Jackson’s defeat should set M’Dowell free.