a detachment of the Twenty-seventh Pennsylvania Militia, under Lieutenant [Delaplaine J.] Ridgway, and some citizens of Columbia. There was also a small guard of the Twenty-seventh Pensylvania Militia at the Columbia side of the bridge. 2. The fourth span (from Wrightsville) of the bridge was selected, and mechanics were employed to separate the roof and sides, leaving only "the arches and a very small portion of the lower chords" for crossing over. It was expected that holes bored into these arches and filled with powder would, by exploding the powder, shiver the timber and cause the span, about 200 feet long, to drop into the river, and thus render the bridge useless to the enemy. This work was superintended by Mr. Robert Crane, who had previously, upon the first alarm, begun this work, and who has cheerfully rendered me every assistance, His report* is herewith inclosed, marked A. Lieutenant Randall, of the City Troop, first, and subsequently Major C. McLean Knox, Ninth New York Cavalry, was placed by the mines to observe whether the enemy approached, with instructions to order the mines to be exploded in time to prevent them from getting over the doomed arch. I relied very much upon the success of this arrangement. 3. A tete-de-point immediately around the bridge to cover the retreat of our troops. A few hopper cars (iron), loaded with iron ore, were retained to barricade the main street leading from York to the bridge. The side streets were obstructed by boards piled together so as to make complete breastworks for defense. This work was performed by the citizens under the directions of Mr. [Samuel H.] Mann, of Wrightsville, the provost-marshal, to whom I indicated the lines of defense. This bridge-head was garrisoned by about 50 of the Twenty-sixth Pennsylvania Militia, very much worn down by their retreat from Gettysburg, and a small guard at the bridge, of the Twenty-seventh Pennsylvania Militia. 4. About three-fourths of a mile in front of the bridge is a ridge which curves in toward the Susquehanna River, and on the upper side, near the river, beyond this, is another height, both of which are good positions for defense against infantry and cavalry. Two small creeks run at the foot of these eminences. But outside of these, above and below Wrightsville, are ridges making in at right angles to the river which, with artillery, would command these defenses. With the force at our command, it was impossible for us to place troops on these ridges. To defend the bridge successfully, these ridges would have to be occupied by our troops, supported by artillery. It would have required, perhaps, five times our number to have garrisoned the line extending from the upper to the lower ridge. Our defense, therefore, contemplated resistance to a raid by the enemy's cavalry and mounted infantry which might be thrown forward to destroy the bridge. York was not occupied by the enemy until 10 a. m. Sunday, June 28, and it was not known what the enemy's designs were. If they came with a column to invade the county it would be impossible to defend the bridge successfully. We therefore strengthened our position by rifle-pits as far as our supply of tools would permit, determined to hold our ground until the development of the enemy showed a superiority in numbers, aided by cannon.