If, in conjunction with McDowell’s movement against Anderson, you could send a force from your right to cut off the enemy’s supplies from Richmond, preserve the railroad bridges across the two (2) forks of the Pamunkey, and intercept the enemy’s retreat, you will prevent the army now opposed to you from receiving an accession of numbers of nearly fifteen thousand (15,000) men, and if you succeed in saving the bridges, you will secure a line of railroad for supplies in addition to the one you now have. Can you not do this almost as well as not, while you are building the Chickahominy bridges? McDowell and Shields both say you can, and positively will, move Monday morning. I wish you to march cautiously and safely. You will have command of McDowell after he joins you, precisely as you indicated in your long dispatch to us of the twenty-first (21st). A. LINCOLN, _President_. As you see, the above example does no more than suggest to General McClellan from a strategic standpoint certain courses open to him. The general-in-chief on the spot is the one to make the decision. To progress in our examples, let us take one issued by the general-in-chief to one of his subordinate generals. Headquarters of the Army, Washington, Feb. 23, 1862. Maj.-Gen. B. F. Butler, U. S. Volunteers,— _General_:—You are assigned to the command of the land forces destined to coöperate with the navy, in the attack upon New Orleans. You will use every means to keep your destination a profound secret, even from your staff officers, with the exception of your chief-of-staff, and Lieut. Weitzel, of the engineers. The force at your disposal will consist of the first 13 regiments named in your memorandum handed to me in person, the 21st Indiana, 4th Wisconsin, and 6th Michigan (old and good regiments from Baltimore). The 21st Indiana, 4th Wisconsin, and the 6th Michigan, will await your orders at Fort Monroe. Two companies of the 21st Indiana, are well-drilled as heavy artillery. The cavalry force already en route for Ship Island, will be sufficient for your purposes. After full consultation with officers well acquainted with the country in which it is proposed to operate, I have arrived at the conclusion that (2) two light batteries fully equipped and (1) one without horses, will be all that are necessary. This will make your force about 14,400 infantry, 275 cavalry, 680 artillery; total 15,255 men. The commanding general of the Department of Key West, is authorized to loan you, temporarily, 2 regiments; Fort Pickens can probably give you another, which will bring your force to nearly 18,000.