up. Wright's advance reached Poolesville last night, and had a smart cavalry skirmish. As the enemy's main body have nearly twenty-four hours the start, Wright can at best only reach their rear guard. The Nineteenth Corps, about 4,000 men, have landed in fragments, destitute of everything, but, as soon as supplied, have been sent forward. They will reach the vicinity of Edwards Ferry to-day. Ord's command, from Baltimore, arrived during the night and has gone forward this morning. It is nearly 5,000. Some of Howe's forces were reported on the Monocacy yesterday, and may join Wright this morning. We hear nothing directly from Hunter. Railroad men say Sullivan's command was at Harper's Ferry yesterday. General Kelley telegraphs from Cumberland that when Hunter left he said he intended to strike the enemy's flank, but where or how he does not state. Message after message has been sent to him, but no reply has been received. All your instructions have been communicated to General Wright, and he will do his best to carry them out; but, from the late hour in which forces fir to take the field have reached here, he will hardly be able to do the enemy much injury. He is directed to pursue him south until further instructions are received from you. While writing the above yours of 8 p. m. is received. I will telegraph to Fort Monroe to send no more of the Nineteenth Corps here than the fragments of Emory's division, still behind. The story about an intended raid on Point Lookout is without foundation. No enemy passed Bladensburg. Railroad communication to Philadelphia will be reopened to-morrow. Baltimore and Ohio Railroad is reported nearly repaired, from the west to Harper's Ferry.

H. W. HALLECK,

Major-General and Chief of Staff.

WASHINGTON, July 15, 1864-6 p. m.

Lieutenant-General GRANT,

City Point, Va.:

From the most reliable information we have been able to collect the raiding force in Maryland consisted of, first, Early's corps, reorganized, in three divisions, under Rodes, Gordon, and Ramseur (Johnson's old), re-enforced in Virginia by conscripts and convalescents to about 12,000; second, Breckinridge's corps (a new one), consisting of two divisions; re-enforced by all the rebel troops at Staunton, Charlottesville, Lynchburg, and in the Valley, to about 12,000; third, the cavalry of McCausland, Ransom, Imboden, Rodes, Bradley Johnson, Gilmor, and Mosby. Ransom seems to have had principal command. Its force is estimated by good observers at from 4,000 to 6,000. All the dismounted men have been remounted on stolen horses. The artillery and trains have also been supplied with fresh animals. They have between twenty and thirty pieces of artillery. Some, however, who prevented to have counted them, say they number much higher. Many estimate the entire force at from 30,000 to 40,000. The mass of evidence would make it a little less than the former number. Their loss at Monocacy and near Silver Springs was considerable, but they say they have made it up by volunteers and conscripts. Their captures have not been valuable, except in horses. The foregoing is formed from the most reliable data that I can obtain,