Alexandria, November 3.—Most of the accounts relative to the attack upon the train at Manassas have been exaggerated. The following is the true version:—

It was about three o’clock on Friday afternoon when the train passed over Bull Run bridge. It proceeded about a mile beyond, when it was thrown from the track. No obstruction was apparent, and the manner in which the Confederates accomplished the fiendish trick was by cutting off the heads of the spikes which confined the rails in position, and undermining the track.