2,000 cavalry on steamers. Left Helena and arrived at the month of White River on the 19th instant. At that point our fleet anchored, and I sent a cutter with the oldest White River pilot to explore and examine the condition of the channel. After sounding what they regarded as the most difficult parts of the river they reported 5 1/2 feet water on the bar and no difficulty above to the point of disembarkation. Before leaving Helena, scouts, pilots, deserters, and citizens all concurred in representing White River in a good condition, with 6 or 7 feet water in the shoalest parts of the channel. I at once landed my cavalry under Colonel Bussey, Third Iowa Cavalry, on the north side of White River, and directed him to proceed to the ferry near Wild Goose bayou and opposite to a place known as the Prairie Landing.

We then commenced ascending White River with our fleet, and after passing all obstructions known to the oldest pilots we encountered a new bar with only 30 inches water in the channel, the river within the last days having fallen at least 5 feet. As our own boats were drawing 3 to 4 feet, we were compelled to change our programme and prepare for a march by land.

Whilst preparing for this movement I received a letter on the 20th instant from Colonel N. P. Chipman, chief of staff, intimating that other movements might require our forces at another point, and knowing that we could not make the march by land and accomplish our object in less than eight or ten days I immediately called in our cavalry and turned our fleet toward Helena, where we safely arrived last night without loss or casualty.

I deeply regret that we could not have been permitted to consummate our plans, as I feel confident that we should have captured the Post, with a large number of prisoners and stores.

Colonel bussey reached the ferry, within 8 miles of the Post, and was informed by severed negroes that the enemy had heard of our approach and commenced evacuating on Monday. Colonel McGinnis also heard the same report at Napoleon, but I do not regard the rumor as authentic.

During our delay at the mouth of the river I sent Colonel McGinnis on steamer Rocket, with Eleventh Indiana Volunteers, to Napoleon, to destroy ferry-boats use there by the enemy. This he fully accomplished, and ascertained the further fact that two regiments of rebels had crossed from Mississippi to Arkansas on Monday last. It was supposed that they had been sent to-re-enforce the Post. It man be, however, that they enemy are leaving Mississippi and concentrating on this side of the river. Within the last few days the enemy have burnt the bridge over Big Creek, and seems to be apprehensive of an attack from Helena. Before leaving I made arrangements to be ready for the call intimated to me by Major-General Curtis, and should have been ready at any time to meet the demand, as the embarkation of troops would be indispensable for that purpose.

Heavy rains have recently fallen and the roads here will some become impassable. I am fearful that the dash heretofore intimated by Major-General Curtis will in consequence prove very difficult of accomplishment. I would be pleased, if it be compatible with the service, that the major-general commanding would give me some general instructions in regard to my future operations.

If I command here I wish to make the enemy and others feel and fear me, but am at a loss to know how far I shall go without specific orders.