Report of Brig. Gen. John J. Peck, U. S. Army, of operations April 5-30.
Near Warwick River, April 30, 1862.
My brigade took position near the Warwick River after dark on the 5th instant.
On the 7th I made a reconnaissance of this river down to the James. From its depth and breadth I found the enemy’s vessels could control the navigation and reach our lines with heavy guns. To secure our left flank from a gunboat attack I constructed batteries Ira Harris and Couch near the .junction of Mill Creek with the Warwick. Since their completion rebel craft have not ventured nearer than the James River. These, with four additional works near the edge of the river, have also forced the enemy’s camps and picket line a long distance back from the Warwick and materially interrupted his communications. This view is strengthened by the fact that within eight or ten days the enemy’s heavier vessels have been seeking positions higher up on the river side of Mulberry Island, from which to reach my lines; 6-inch elongated shells have been thrown from them over the advance batteries.My armament consists of eight 10-pounders, altogether too light for the proper service of the several batteries. With a small number (say two) of 8-inch howitzers and two 8-inch mortars I could command  most of Mulberry Island and reach their landings on the James River side.
James River from Newport News to a point about 4 miles above the mouth of the Warwick has an average breadth of nearly 5 miles, enabling the smaller vessels to keep out of the range of batteries on the Peninsula. At that point it is reduced to about 1 ¾ miles, and continues of this width some 2 miles. Above the light-house on Mulberry Point it widens out again. Would not possession of the island enable the commanding general to control in a considerable degree the James River in case the Navy fails to do the work?
I am, very respectfully, your obedient servant,
JOHN J. PECK,
General R. B. MARCY,
Chief of Staff, Army of the Potomac.
MAY 1, 1862.
Respectfully forwarded. I think more heavy artillery necessary to make much impression on Mulberry Island than General Peck specifies.
E. B. KEYES,
Brigadier- General, commanding Fourth Corps.
Official Records of the Rebellion: Volume Eleven, Chapter 23, Part 1: Peninsular Campaign: Reports, pp.307-308
web page Rickard, J (4 February 2007), http://www.historyofwar.org/sources/acw/officialrecords/vol011chap023part1/02017_01.html