loss to account for this sudden evacuation on the part of the rebels, as, in addition to a most skillfully constructed line of defense, the position possesses natural advantages which render it almost impregnable, and, with the number of men which I know to have occupied it, the position might have been maintained for a considerable time and the tacks of reducing it rendered one of extreme difficulty and danger to a much larger force than I had at my disposal. I n advancing to Mount Pleasant Creek our pickets had some skirmish with the rebels; indeed, during our entire advance to Saint John's Bluff the guerrillas continued to show themselves in the woods, and occasionally to fire at us, even after the evacuation of the batteries. They, however, did us no injury.

On the 2nd instant a scouting party of the Forty-seventh Regiment Pennsylvania Volunteers, under Captain Keck, of that regiment, surprised a camp of the rebels, taking some camp equipage and about sixty stand of arms of all descriptions, but chiefly rifles. The men effected their escape, having horses and being much favored by the intricate nature of the ground.

I am much indebted to the gunboats, Captain Steedman, U. S. Navy, in command, for the prompt and energetic manner in which they assisted at the disembarkation of the troops, and the valuable assistance rendered by their howitzers in covering the landing and advance of the infantry.

On leaving this point it is my intention to blow up the magazines and utterly destroy the works on Saint John's Bluff, and I am at present engaged in removing the guns, which I propose to take with me, they being of considerable value, their number and caliber as follows, viz: Two 8-inch columbiads, two 8-inch guns, smooth bore, two 8-inch howitzers, and two 4.6-inch rifled guns. I return the transport Cosmopolitan, and respectfully request that I may receive by her rations for my command for ten days from the 10th instant, as it will yet take me some time to complete my work on this river.

Owing to information received yesterday, the 3rd instant, as to the strength of the enemy, I deemed it expedient, on consultation with Captain Steedman, U. S. Navy, commanding gunboats, to send the Cosmopolitan to Fernandina, Fla., and to call on that garrison for re-enforcements to my command. This call Colonel Rich, Ninth Regiment Maine Volunteers, commanding, promptly answered to, by sending 300 men, who arrived early this morning. The occasion for which they were required, hoverer, having passed, I sent them back per this ship. The gunboats proceeded up the river yesterday and will return this ship. The gunboats proceeded up the river yesterday and will return this afternoon. Captain Steedman, who has just returned, states that there is much corn on the bank of the river. This I propose to take with me, if possible; if not, to destroy it. He (Captain Steedman) was informed that three Georgia regiments were to have arrived at Jacksonville this morning; but in consequence of the evacuation were ordered back.

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

J. M. BRANNAN,

Brigadier-General, Commanding.

Major General O. M. MITCHEL,

Commanding Department of the South, Hilton Head, S. C.

HDQRS. EXPEDITION TO SAINT JOHN'S RIVER,
Steamship Ben De Ford, October 13, 1862.

COLONEL: In accordance with orders received from headquarters Department of the South, I assumed command of the following forces intended