employed on picket duty in guarding the telegraph line between Washington and Aquia Creek, came to Alexandria yesterday. Was returning last night to join his squad, and about 16 miles from Alexandria, on telegraph line, reached a point 1 mile from his squad. On the wa he passed cavalry, citizens, and contrabands fleeing toward Alexandria. Being unarmed, and seeing a man near the road who had jus been killed, he returned. The fugitives reported the rebel cavalry in considerable force some distance behind. This is probably the Prince William Cavalry, of which a scout gave information last night. I have just ascertained that the telegraph is not yet cut. Colonel Close reports to General Slough this morning, on the authority of the men who escaped, that Company A, Sixteenth Virginia, sent on guard duty at some point on the railroad between this place and Manassas, were all captured some time last night.

Very respectfully,

H. HAUPT,

Colonel, &c.

ALEXANDRIA, VA., August 28, 1862 - 12.50 p. m.

His Excellency PRESIDENT LINCOLN:

I ma much gratified to be able to inform you that Colonel Scammon is safe, and has returned to Alexandria. I went out on an engine to meet him and bring him in. He held Bull Run Bridge a long time against a very superior force; retired at last in perfect order, eluded the efforts of the enemy to surround him, and brought off his whole command with but little loss. I have advised General McClellan of his presence. He has important information to communicate. The rebel forces at Manassas were large, and several of their best generals were in command. I have sent out a reconnoitering party of 200 sharpshooters by rail, with operations and wire to repair the telegraph, make communication, and report observation.

H. HAUPT.

ALEXANDRIA, VA., August 28, 1862 - 3.30 p.m.

Major-General HALLECK:

Brigade across Pohick, 1 mile west of Burke's Station and 14 from Alexandria, destroyed. Reconnoitering party could proceed no farther. Fireman, who was taken prisoner by the rebels and escaped, says that Bull Run Bridge was set on fire yesterday afternoon. He saw it on fire as he was making off through the bushes from Bull Run and soon after heard it fall. It is clear, therefore, that the Army of Virginia can receive no more supplies by rail at present, and must flank the enemy by a movement to the east, cut its way through, or be lost.

H. HAUPT.

ALEXANDRIA, VA., August 28, 1862 - 10.50 p. m.

Major General H. W. HALLECK, General-in-Chief:

The result of our railway reconnaissance to-day was extremely gratifying. The construction corps reconstructed the bridge across Pohick, the operators repaired telegraph lines, and the wounded at Fairfax were all brought off safely. Important intelligence was obtained from