"From Lee's Mill a line of works extends across Mulberry Island (or is supposed to do so).

"At Southall's Landing is another formidable group of works, and from here, too, they extend apparently across the James.

"These groups of field works were connected by rifle trenches or parapets, for nearly the whole distance.

"They are far more extensive than may be supposed, from the mention of them I make; and every kind of obstruction which the country affords, such as abattis, marsh, inundation, &c., was skillfully used. The line is certainly one of the most extensive known to modern times.

"The country on both sides the Warwick, from near Yorktown down, is a dense forest, with few clearings. It was swampy, and the roads impassable during the heavy rains we have constantly had, except where our own labors had corduroyed them.

"If we could have broken the enemy's line across the isthmus, we could have invested Yorktown, and it must, with its garrison, have soon fallen into our hands.

"It was not deemed practicable, considering the strength of that line, and the difficulty of handling our forces (owing to the impracticable character of the country), to do so.

"If we could take Yorktown, or drive the enemy out of that place, the enemy's line was no longer tenable. This we could do by siege operations. It was deemed too hazardous to attempt the reduction of the place by assault."

The plan of the approaches and their defenses, as determined upon and finally executed, is exhibited in the accompanying map. It was, in words, to open the first parallel as near as possible to the works of the enemy, and under its protection to establish, almost simultaneously, batteries along the whole front, extending from York River, on the right, to the Warwick, on the left (a chord of about one mile in length, the principal approaches were directed against the cast end of the main work (which was most heavily armed, and bore both on the water and land), and lay between Wormley's Creek and York River. There, also, were placed

the most of the batteries designed to act against the land front, to enfilade the water batteries, and to act upon Gloucester. I designed at the earliest moment to open simultaneously with several batteries, and as soon as the enemy's guns, which swept the neck of land between Wormley's Creek and the Warwick, were crippled, and their fire kept down, to push the trenches as far forward as necessary, and to assault York town and the adjacent works.

The approaches to the batteries, the necessary bridges, and the roads to the depots, had been vigorously pushed to completion by the troops under Generals Heintzelman and Sumner, and were available for infantry, and in some instances for artillery, on the 17th of April, when the batteries and their connections were commenced, and labor upon them kept up, night and day, until finished.

Some of the batteries, on easy ground and concealed from the view of the enemy, were early completed and armed, and held ready for any emergency, but not permitted to open, as the return fire of the enemy would interfere too much with the labor on other and more important works. The completion of the more exposed and heaviest batteries was delayed by storms, preventing the landing of guns and ammunition. It having been discovered that the enemy were receiving artillery stores at the wharf in Yorktown, on May 1st, Battery No. 1 was opened with effect upon the wharf and town.

me.

On the 22d of April, General Franklin, with his division from General McDowell's corps, had arrived and reported to The garrison of Gloucester Point had been reinforced and the works strengthened; but as this division was too small to detach to the Severn, and no more troops could be spared, I determined to act on Gloucester by disembarking it on the north bank of the York River, under the protection of the gun-boats. The troops were mainly kept on board ship while the necessary preparations were made for landing them, and supporting them in case of necessity. For a full account of this labor, I refer to the report of Lieut.-Col. B. S. Alexander, of the Engineer Corps detailed for this expedition.

While the siege works were being rapidly completed, the roads on the left wing necessary for communication and ad

vance were opened and corduroyed over the marshes, batteries were erected to silence the enemy's guns and drive him from his works at Winn's and Lee's Mills, preparatory to the general attack, active reconnoissances were continually going on, and attempts in force made to drive the enemy from the banks.

The result of various reconnoissances made under the immediate direction of Gen. W. F. Smith, commanding 2d Division, 4th Corps, led to the belief that the weakest point of that part of the enemy's lines, was opposite a field, where it was ascertained that there was a dam covered by a battery known to contain at least one gun. It was determined to push a strong reconnoissance on this point, to silence the enemy's fire, and ascertain the actual strength of the position, being prepared to sustain the reconnoitering party by a real attack, if found expedient.

Gen. W. F. Smith was directed to undertake the operation on the 16th of April. He silenced the enemy's guns, discovered the existence of other works, previously concealed and unknown, and sent a strong party across the stream, which was finally forced to retire with some loss; but Gen. Smith intrenched himself in a position immediately overlooking the dam and the enemy's works, so as to keep them under control, and prevent the enemy using the dam as a means of crossing the Warwick to annoy us.

Many times towards the end of the month, the enemy attempted to drive in our pickets and take our rifle-pits near Yorktown, but always without success. As the siege progressed it was with great difficulty that the rifle-pits on the right could be excavated and held, so little covering could be made against the hot fire of the enemy's artillery and infantry.. Their guns continued up to a late hour of the night of the 3d of May.

Our batteries would have been ready to open on the morn ing of the 6th May at latest, but on the morning of the 4th it was discovered that the enemy had already been compelled to evacuate his position during the night, leaving behind him all his heavy guns uninjured, and a large amount of ammunition and supplies.