HEADQUARTERS DEPARTMENT OF THE SOUTH, Hilton Head, S. C., June 28, 1864.

Brigadier General JOHN P. HATCH,
Commanding Dist. of Hilton Head, &c., Hilton Head, S. C.:

I am instructed by the major-general commanding to inform you that the expedition to leave here at sunset on Thursday next will be placed entirely under your command. Major-General Foster may accompany it, but only to give advice and assistance.

The force will consist, all the troops that can be spared from this district; second, all the troops that can be spared from the District of Florida, under command of Brigadier General W. Birney; third, all the troops that can be spared from Beaufort, under the command of Brigadier General R. Saxton or Brigadier General E. E. Potter; fourth, a detachment from the Northern District, to be under the command of a competent officer. It is proposed to take as large a proportion of artillery and cavalry as the transportation to be prepared for one section of artillery with an extra caisson, 40 cavalrymen and horses, besides 25 or 30 cavalrymen and horses Brigadier-General Birney will bring with him, and ten teams.

The major-general commanding thinks it will be better if you can arrange to take an additional section of artillery with an extra caisson, and I have written to Brigadier-General Saxton to do this, and orders have been given to Captain J. H. Moore, chief quartermaster, to take ten teams. Two companies of the engineer battalion will accompany the expedition for the purpose, in the first place, of rebuilding a certain bridge, for which purpose they should be dispatched in advance, in a small steamer; after which they will perform the duties of engineers soldiers on the march. One company of infantry will be advanced for the purpose of placing the torpedoes. An adequate force of naval gun-boats will co-operate. Colonel Boutelle, U. S. Survey, will pilot the boats to the landing at night. It is expected that this expedition will sail at sunset on Thursday next from this point, on which day Brigadier-General Birney is to be here with his forces from Florida. It is expected that a landing and a march of 10 miles will be made during Thursday night. Detailed orders must be prepared respecting the embarkation and disposition of the troops. Previous to the sailing of the expedition, sealed orders must be given to the commanding officer of each transport, marked on the outside, "To be opened after leaving the harbor---miles, and after steering southerly in a ----direction." After which the lights must be put out on all the boats of the expedition.

Major-General Foster desires me to say that the detailed orders for sailing, as indicated above, will be prepared at these headquarters if you wish it. The chief quartermaster has been instructed to take your orders in all material relating to the expedition as though they came from these headquarters. The troops must be provided with three days' cooked rations of bread and meat and six days' rations of coffee and sugar and salt, in knapsacks or haversacks, the former preferred. The men to carry 10 rounds of cartridges in each pocket, in addition to what can be put in their cartridge-boxes; 40 rounds extra for each man will be put on each transport, to be stored in a safe place and one convenient to get at. The troops will be in light marching order. No baggage of any description will be