[Inclosure E.]

HEADQUARTERS EASTERN DISTRICT, Fort Union, N. Mex., March 22, 1862.

Colonel J. P. SLOUGH,
First Regiment Colorado Volunteers:

COLONEL: Yours in answer to mine of this date is received. You must be aware that no part of the regular force of this district would have been turned over to you had the instructions of Colonel Canby of the 16th instant been received twelve hours earlier. I had trusted that this knowledge and the fact that your movement is in direct conflict with Colonel Canby's positive orders and in disregard of his anxiety for the safety of this department that my request would have been answered differently. The force offered you in my first note was ample to answer all purposes of annoying and harassing the enemy, as you state that as the object of your advance. You, however, indicate that an attack upon the enemy's position at San Antonio is within your calculations. This most certainly is or will be in violation of Colonel Canby's instructions, and, if unsuccessful, must result in the entire loss of the Territory, at least for a time, and render its reconquest march more difficult. I must urge upon you to reconsider your decision and to submit to the plan of the department commander. The arrangements I proposed in my first letter on this point give you sufficient force to comply fully with Colonel Canby's orders to "annoy the enemy." With due deference to your superior judgment I must insist that you plans do not meet either of these ends, but must inevitably result in disaster to us all. Colonel Canby must have had good reasons for the change direct in the plans he at first approved, and his anxiety to have the change made known is indicated by his sending duplicates of his instructions by different messengers, both of which have been received.

In the name of the department commander, of the best interests of the service, and of the safety of all the troops in this Territory, I protest against this movement of yours, made as it is two days before the time first agreed upon, and as I conceive in direct disobedience of the orders of Colonel Canby.

I am, colonel, very respectfully, your obedient servant,

G. R. PAUL,

Colonel Fourth N. Mex. Vols., Commanding Eastern District.

WAR DEPARTMENT, Washington City, D. C., March 24, 1862.

Hon. W. H. SEWARD, Secretary of State:

SIR: The Secretary of War directs me to acknowledge the receipt of your letter of the 13th instant, relative to the occupation, by United States troop, of the left bank of the Rio Grande, with a view of preventing trade between the adjacent region of Texas and the Mexican bank of the river, particularly Matamoros, and in reply to inform you that your letter has received careful consideration, with the conclusion that the condition of the United States forces does not admit at present of the detachment of the necessary troops for such an expedition.

I have the honor to be, very respectfully, your obedient servant,

P. H. WATSON,

Assistant Secretary of War.