HELENA, April 29, 1864.

Major CORMICHEAL,

Fifteenth Illinois Cavalry:

SIR: I furnish you the steam-boat Dove, and a colored guard of 40 men, 30 infantry and 10 artillerists. You will that 100 cavalry, with five days' rations and forage, and proceed to the mount of White River, where you will cross with the commanding officer of the naval station, and make a raid on the island between the mounts of While and Arkansas Rivers. You will make a careful search for enemies, guerrillas, negro stealers, and horses thieves. You will capture of destroy all who are found in arms or giving aid and comfort to the enemy.

You will seize all horses and mules fit for the service found in possession will seize all horses and mules to the United States, also arms and munitions. You will look carefully for boats, and destroy them. This accomplished, you will go to Major Henry's landing, and send a scout from there to Lyconia to Gillan's. You will send the Dove up to Gillan's, and cause a party of 50 men to land there, and to come down to meet you. When you have got all the men together, you will return to Gillan's and re-embark. In this expedition you are free to after the palm.

You are to use your discretion as to landing opposite island 66 and below, or at 63, and make a raid in to Mississippi. The object in the same as on the last raid, to capture rebels in arms, to seize from disloyal person horses and mules fit for cavalry service and afford particular protection for refugees into our lines. If you can capture Grant of Packs [?] or Sanders, or any of the persons who have plotted the capture of Island 63, it is desirable. Your especial attention is directed to the capture of rebel mails and the destruction of any small crafts in crossing the river.

Your obedient servant,

BUFORD,

Brigadier-General, Commanding.

SAINT LOUIS, MO., April 29, 1864-11 p. m .

(Received Culpeper, 30th.)

Lieutenant-General GRANT:

General Sherman is urgent that the dismounted cavalry of his command should be sent forward without horses. I telegraph you direct that you may give such instructions as may be necessary. I repeat to you what I have already stated. In present of secret dangers, which I know to exist and hope soon to circumvent, and the posture of affairs in Arkansas and Louisiana, to leave the department without adequate force would be most hazardous. If the two regiments of infantry sent to garrison Columns and Paducah were sent back, I could send two or three of the dismounted cavalry regiments to the front. These regiments were eminently qualified by discipline and order for the work, while the lack of these qualities in the cavalry has gives rise to frequent disorder and complaints already. Please direct. Rest assured that what I say about secret dangers is well considered and based on facts.

W. S. ROSECRANS,

Major-General.