Telegram From General Halleck

To General G. B. Mcclellan., Washington, D. C., October 6, 1862.

MAJOR-GENERAL McCLELLAN:

I am instructed to telegraph you as follows: The President directs that you cross the Potomac and give battle to the enemy, or drive him south. Your army must move now, while the roads are good. If you cross the river between the enemy and Washington, and cover the latter by your operation, you can be reinforced by thirty thousand men. If you move up the valley of the Shenandoah, not more than twelve or fifteen thousand can be sent you. The President advises the interior line between Washington and the enemy, but does not order it. He is very desirous that your army move as soon as possible. You will immediately report what line you adopt, and when you intend to cross the river; also to what point the reinforcements are to be sent. It is necessary that the plan of your operations be positively determined on, before orders are given for building bridges and repairing railroads. I am directed to add that the Secretary of War and the General-in-chief fully concur with the President in these directions.

H. W. HALLECK, General-in-Chief.