The object of your expedition is one of vital importance, the capture of New Orleans. The route selected is up the Mississippi River, and the first obstacle to be encountered (perhaps the only one) is in the resistance of Forts St. Philip and Jackson. It is expected that the navy can reduce these works; in that case, you will, after their capture, leave a sufficient garrison in them to render them perfectly secure; and it is recommended, that on the upward passage, a few heavy guns, and some troops, be left at Pilot Station (at the forks of the river), to cover a retreat in the event of disaster. These troops and guns, will, of course, be removed as soon as the forts are captured. Should the navy fail to reduce the works, you will land your forces and siege train, and endeavor to breach the works, silence their fire, and carry them by assault. The next resistance will be near the English Bend, where there are some earthen batteries; here it may be necessary for you to land your troops and coöperate with the naval attack, although it is more than probable, that the navy, unassisted, can accomplish the result. If these works are taken, the city of New Orleans necessarily falls. In that event, it will probably be best to occupy Algiers with the mass of your troops, also, the eastern bank of the river above the city; it may be necessary to place some troops in the city to preserve order, but if there appears sufficient Union sentiment to control the city, it may be best for purposes of discipline to keep your men out of the city. After obtaining possession of New Orleans, it will be necessary to reduce all the works guarding its approaches from the east, and particularly to gain the Manchac Pass. Baton Rouge, Berwick Bay, and Fort Livingston will next claim your attention. A feint at Galveston may facilitate the objects we have in view. I need not call your attention to the necessity of gaining possession of all the rolling stock you can on the different railways, and of obtaining control of the roads themselves. The occupation of Baton Rouge by a combined naval and land force, should be accomplished as soon as possible after you have gained New Orleans. Then endeavor to open your communication with the northern column by the Mississippi, always bearing in mind the necessity of occupying Jackson, Mississippi, as soon as you can safely do so, either after, or before you have effected the junction. Allow nothing to divert you from obtaining possession of all the approaches to New Orleans. When that object is accomplished to its fullest extent, it will be necessary to make a combined attack on Mobile, in order to gain possession of the harbor and works, as well as to control the railway terminus at the city. In regard to this, I will send more detailed instructions as the operations of the northern column develop themselves.