Adam Badeau, Military history of Ulysses S. Grant from April 1861 to April 1865. Volume 2

All necessary preparations for carrying these directions into operation may be commenced at once. The reserves of the Ninth corps should be massed as much as possible. Whilst I would not now order an unconditional attack on the enemy's line by them, they should be ready, and should make the attack, if the enemy weakens his line in their front, without waiting for orders. In case they carry the line, then the whole of the Ninth corps could follow up so as to join or co-operate with the balance of the army. To prepare for this, the Ninth corps will have rations issued to them the same as to the balance of the army. General Weitzel will keep vigilant watch upon his front, and if found at all practicable to break through at any point, he will do so. A success north of the James should be followed up with great promptness. An attack will not be feasible unless it is found that the enemy has detached largely. In that case, it may be regarded as evident that the enemy are relying upon their local reserves, principally, for the defence of Richmond. Preparations may be made for abandoning all the line north of the James, except enclosed works; only to be abandoned, however, after a break is made in the lines of the enemy.

By these instructions, a large part of the armies operating against Richmond is left behind. The enemy, knowing this, may, as an only chance, strip their lines to the merest skeleton, in the hope of advantage not being taken of it, whilst they hurl everything against the moving column, and return. It cannot be impressed too strongly upon commanders of troops left in the trenches, not to allow this to occur without taking advantage of it. The very fact of the enemy coming out to attack, if he does so, might be regarded as conclusive evidence of such a weakening of his lines. I would have it particularly enjoined upon corps commanders, that in case of an attack from the enemy, those not attacked are not to wait for orders from the commanding officer of the army to which they belong, but that they will move promptly, and notify the commander of their action. I wish, also, to enjoin the same action on the part of division commanders, when other parts of their corps are engaged. In like manner, I would urge the importance of following up a repulse of the enemy.