Headquarters, Maryland Heights, June 25, 1863-5 p. m.

Secretary of War:

Have made three attempts to communicate with the enemy as to the wounded, &c., at Winchester. They received the flags and letters, and fixed times for replying, but they failed to reply. The last time fixed was 5 p. m. yesterday, and they met us with information that no reply had been received, and proposed when received to send it in to Bolivar Heights . This is declined . My letter was addressed to General Lee, at Berryville, where I knew he was on the 23rd instant. I can hold Harper's Ferry.

Dan. Tyler,

Brigadier -General.

To-day the howitzers received from the Washington Arsenal were placed in position, and I consider the defenses so far completed that, with the force now here, Maryland Heights should be held against Lee's army. A few more 24 -pounder howitzers would add to the defenses, and should be furnished at an early day. Jewett's brigade, from Heintzelman's corp, arrived to=day, 1, 700 strong, with one light battery, two or three squadrons of cavalry, making the effective force for duty at 6 p. m. about 10, 500 men . The arrival of Jewett's brigade increased the garrison to the maximum required for a good defense of the Maryland Heights and the protection of the ford and bridge over the Potomac at Harper's Ferry. Ten thousand effective men will thoroughly cover the bank of the Potomac, the ground between Fort Duncan and Maryland Heights, and thoroughly and effectively garrison the Heights, so as to put it beyond the power of 20, 000 men to carry the Heights by assault. In the defense of the Maryland side, three light batteries are at this time appropriated, and will always be indispensable in case of an investment or attack. June 26. - With a clear atmosphere, we have this morning a capital view from the signal station of the whole country from Charlestown to Sharpsburg, and it is clear to my mind that entire force of Lee's army has passed on toward Pennsylvania, and that the force discernible in the Valley's is merely enough to guard the Shepherdstown Ford and the line of communication from Winchester to Sharpsburg; and under this impression, I telegraphed Major-General Hooker as follows:

Headquarters, Maryland Heights, June 26, 1863-3 p. m.

Major -General Hooker, Commanding Army of the Potomac:

The signal officer reports with the best possible view, two small camps only on Virginia side, near Shepherdstown, with heavy cavalry pickets extending to Halltown ; a large camp to the right of Sharpsburg(guard to the ford), with sixty walltens pitched.

Dan. Tyler,

Brigadier -General.

I add this Colonel W. F. Raynolds'(U. S. Engineers) report of the engineering operations on the Maryland side of the Potomac from June 16 to 26, and will only say that, within the short period that Colonel W. F. Raynolds was employed, the modifications and changes on the work were carried on with great skill and energy, and were so far completed on June 26 that I telegraphed to the Secretary, "I can hold Maryland Heights. "