Had McClellan received notice that the Valley army was approaching, a day’s delay would have given him a fine opportunity.  More than one course would have been open to him.  He might have constructed formidable intrenchments on the north bank of the Chickahominy and have brought over large reinforcements of men and guns; or he might have turned the tables by a bold advance on Richmond.  It was by no means inconceivable that if he detected Lee’s intention and was given time to prepare, he might permit the Confederates to cross the Chickahominy, amuse them there with a small force, and hurl the rest of his army on the works which covered the Southern capital.  It is true that his caution was extreme, and to a mind which was more occupied with counting the enemy’s strength than with watching for an opportunity, the possibility of assuming the offensive was not likely to occur.  But, timid as he might be when no enemy was in sight, McClellan was constitutionally brave; and when the chimeras raised by an over-active imagination proved to be substantial dangers, he was quite capable of daring resolution.  Time, therefore, was of the utmost importance to the Confederates.  It was essential that Porter should be overwhelmed before McClellan realised the danger; and if Jackson, in fixing a date for the attack which would put a heavy tax on the marching powers of his men, already strained to the utmost, ran some risks, from a strategical point of view those risks were fully justified.

In the second place, an operation such as that which Lee had devised is one of the most difficult manoeuvres which an army can be called upon to execute.  According to Moltke, to unite two forces on the battle-field, starting at some distance apart, at the right moment, is the most brilliant feat of generalship.  The slightest hesitation may ruin the combination.  Haste is even more to be dreaded.  There is always the danger that one wing may attack, or be attacked, while the other is still far distant, and either contingency may be fatal.  The Valley campaign furnishes more than one illustration.  In their pursuit of Jackson, Shields and Fremont failed to co-operate at Strasburg, at Cross Keys, and at Port Republic.  And greater generals than either Shields or Fremont have met with little better success in attempting the same manoeuvre.  At both Eylau and Bautzen Napoleon was deprived of decisive victory by his failure to ensure the co-operation of his widely separated columns.

Jackson and A.P.  Hill, on the morning of the 26th, were nearly fifteen miles apart.  Intercommunication at the outset was ensured by the brigade under Branch; but as the advance progressed, and the enemy was met with, it became more difficult.  The messengers riding from one force to the other were either stopped by the Federals, or were compelled to make long detours; and as they approached the enemy’s position, neither Hill nor Jackson was informed of the whereabouts of the other.