Reports of Brig. Gen. John G. Barnard, U. S. Army, Chief Engineer Army of the Potomac, of operations during the siege.
This preliminary work was so far complete on the 17th of April that it was deemed practicable to commence the construction of batteries, and the following decided on:
Battery No. 1, five 100-pounder Parrotts and one 200-pounder Parrott at Farinholt’s house. Battery No. 2, fifteen guns, 4 1/2-inch 30 and 20 pounders, 1,500 yards from Red Redoubt, and 2,000 yards from big gun. Battery No. 3, six guns, 20-pounder Parrotts, 1,900 yards from  Red Redoubt. Battery No. 4, ten 13-inch mortars, Moore’s plateau. Battery No. 5, four 20-pounder Parrotts, hear Warwick road.
N. B.—Six 20-pounders were put in this battery.
Batteries Nos. 1 and 2 were immediately commenced and finished (essentially finished) in three days. No. 3was commenced, but its construction was retarded by circumstances unnecessary to explain. The sites of Nos. 4 and 5 were not definitely fixed until two or three days later, and another, Battery No. 6, for six 4 ½ k-inch ordnance rifled guns, was determined upon. Portions of parallel connecting Nos. 2and 3, and from the left of Yorktown road to No. 5, were commenced in the edge of the woods by daylight on the 25th. The same night a parallel was run through the open ground from No. 3 to connect with those portions just mentioned, and carried to a depth of 4 feet and a width of 6 feet, affording good cover. The same night a portion of parallel was commenced from near the point marked on the map as Redoubt C to near the head of the ravine toward the York River, and carried to dimensions to afford cover.
On the night of the 27th a parallel was run across from the head of ravine in one night to the York River (or rather to the edge of the bluff), and on the night of the 29th a branch or boyau was run from this to a point 200 yards more advanced on the bluff, from which the whole area between us and the fortress was seen, the gorge of the first redoubt taken in reverse, and the Red Redoubt plunged into.
I have not time to enter into the details of works and batteries, but will simply state that Battery No. 6 was changed into a battery for five sea-coast mortars, Battery No. 5 enlarged to contain eight 20-pounders, and Battery No. 3 enlarged to contain seven 20-pounder Parrotts. Batteries 7 and 8, for six 20-pounder Parrotts each, were built to operate on the work at Wynn’s Mill; Battery No. 9, for ten 10-inch siege mortars; battery No. 10, for three 100-pounder Parrotts and seven 4 ½ -inch ordnance; Battery No. 11, for five 10-inch sea-coast mortars; Battery No. 12, for five 10-inch and five 8-inch siege mortars; Battery No. 13, for three 30-pounder Parrotts and four 30-pounder Parrotts, directed at the redoubt at Yorktown works and on to batteries capable of being used on Gloucester; Battery No. 14 for three 100-pounder Parrotts and one 100-pounder James, to operate on Yorktown water batteries and Gloucester. Another 200-pounder Parrott was ordered to Battery No.1.
Redoubts A and B, for strengthening our line, were finished, Redoubt C well advanced, and Redoubt D just commenced on the night of May
3. A parallel had been run from Redoubt A to Battery No. 5, obstructions and portions of parallel from Redoubt A to Batteries 7 and 8. The foregoing applies to the state of the works on May 3; not to the particular time at which they were finished. A battery for two 8-inch siege howitzers was being commenced in a clearing south of the Wynn’s Mill works, to enfilade that position, and two 8-inch mortars were to be put in position to operate on the works in front of General Smith’s position.
On the night of May 3 all the batteries were armed (i. e., contained their armament) except three 100-pounders in No. 10, seven Parrott guns in No. 13, four 100-pounders in No. 14, and part of the sea-coast and siege 10 and 8 inch mortars were yet to be placed in battery.
Official Records of the Rebellion: Volume Eleven, Chapter 23, Part 1: Peninsular Campaign: Reports, pp.318-319
web page Rickard, J (4 February 2007), http://www.historyofwar.org/sources/acw/officialrecords/vol011chap023part1/02020_01.html