G. S. Hillard, Life and Campaigns of George B. McClellan, Major-General , U. S. Army

And, strange to say, though this was the earliest-settled portion of the whole country and full of historical interest, serious difficulties were encountered from the want of accurate topographical knowledge of the region before them. The common maps were found to be so incorrect as to be of little or no value. Reconnoissances, frequently made at great risk, proved the only trustworthy sources of information.

The progress of our army would have been slow had natural difficulties alone been in their path; but they found themselves met by a foe whose courage and energy they were too brave themselves not to respect. Among the Confederates there were unity of purpose and concerted action towards a common end. They knew that time was on their side, and their great object was to gain time and delay our progress as much as possible. Since leaving Manassas, they had been diligently at work, without the loss of an hour, in strengthening all available points by skilfully constructed works. It was found that Warwick River was controlled by the Confederate gunboats for some distance from its mouth,--that the fords had been destroyed by dams, the approaches to which were generally through dense forests and deep swamps and defended by extensive and formidable works,--and that Yorktown was strongly fortified, armed and garrisoned, and connected with the defences of the Warwick