Corps were landed on Monday. General Emory has also reported in person and says that the remainder of two divisions of his corps is close at hand. The head of General Wright's column passed Fort Reno at 5 p. m., moving out on the Rockville road. This force consists of his own two divisions and of the troops of the Nineteenth Corps, in all about 15,000 men. Colonel Lowell's cavalry, which is serving with him, amounts to about 750 men. Wright will move on with all practicable energy, but as yet his command is inferior in numbers to the enemy. Orders were sent to General Ord at 4. 10 p. m. to move to Washington as soon as he was satisfied that the enemy left his front, bringing his troops by rail. General Halleck informs him that all the evidence went to show that the enemy was moving off by Edwards Ferry, and that it was not probable that any important force remained near Baltimore. Wright has been assigned to the chief command according to your orders. Of Hunter we know nothing. Lowell attacked McCausland, who covers the rear of Early's column, at Rockville at about 5 p. m. Lowell charged them with four companies of his regiment and a body of dismounted men, but found them too strong to break through. He lost about 30 killed and wounded, and brought away some 50 prisoners, besides killing and wounding a number of the enemy. His retreat was favored by the dust which covered his flanks and prevented McCausland from seeing his weakness. The railroad between here and Baltimore proves to be totally unharmed, and trains will be running on it to-morrow morning. The telegraph between here and Philadelphia is working to-night. The night is bright and favorable for marching.

C. A. DANA.

WAR DEPARTMENT,

July 13, 1864-1. 15 p. m.

Lieutenant-General GRANT:

It is now pretty certain that the rebels have retreated by way of Rockville toward Edwards Ferry. McCook reports that both Early and Breckinridge moved out in the night, reaching Rockville at 3 a. m. with 200 wagons and a drove of 2,000 cattle. Ninety wounded rebel soldiers and eleven officers were found this evening in Mr. Blair's house at Silver Spring. McCook reports that some wounded are also left on the ground in front of Fort Stevens. Wright with Lowell's calvalry is moving in pursuit by the River road. No news from Hunter. Our loss by the siege is about 300 killed and wounded. Colonel McCallum sent out to examine the Baltimore and Ohio Railroad reports it unhurt.

C. A. DANA.

HEADQUARTERS OF THE ARMY,
Washington, July 13, 1864.

Honorable E. M. STANTON,

Secretary of War:

SIR: I deem it my duty to bring to your notice the following facts: I am informed by an officer of rank and standing in the military service that the Honorable M. Blair, Postmaster-General, in speaking