No.2. Reports of Brig. Gen. John G. Barnard, U. S. Army, Chief Engineer of operations from May 23, 1861, to August 15, 1862.
[p.119: 29th JUNE: BATTLE OF SAVAGE'S STATION]
The headquarters left Savage Station between 2 and 3 a. m. June 29. I separated from them, and proceeded at once to the camp of Captain Duane, following the route I had examined the night before, and over which General Sykes’ division had passed during the night. (This route is not delineated on the campaign map.) The road was in good condition, but I found the corduroy over the swamp required constant attention, and recognizing the inutility, or rather impossibility, of constructing for the emergency any other crossing (Captain Duane’s officers having been making additional explorations), I directed him to make it his especial business to keep this route practicable. Portions of the wagon trains and General Heintzelman’s corps passed at this bridge during the day. From this point I proceeded to the White Oak Swamp Bridge, and found the trains and troops rapidly passing. I then rejoined the headquarters at the house just beyond, south side of the swamp. As the passage of the army through or over this swamp [p.120] was one of the difficulties of the march, I deem these particulars worthy of record.
General Keyes’ corps had crossed on the 28th, with orders to take a position to cover our débouchés from the swamp and our line of march toward the James. General Woodbury had been directed to communicate with him and assist him by reconnaissances, and Lieutenant McAlester had been ordered by me to proceed to his positions and make such arrangements there, such as slashings, obstructing roads, &c., as he could. Colonel Alexander had also, in execution of the duties assigned him, been on this ground and communicated with the commanding general concerning it.
Official Records of the Rebellion: Volume Eleven, Chapter 23, Part 1: Peninsular Campaign: Reports, pp.119
web page Rickard, J (20 June 2006), http://www.historyofwar.org/source/acw/officialrecords/vol011chap023part1/00002_15.html