You can buy these orange-colored, nickle-plated wire-frame glasses on eBay with the assurance of several books that they were worn by sharpshooters in the Civil War. Ahem.
One sharpshooter (today he would be called a sniper) played a prominent role in the 1863 siege of Knoxville and therefore figures in the novel. The sharpshooter in question, firing from the tower at the Bleak House mansion where Gen. Longstreet kept his headquarters, mortally wounded Union Gen. William P. Sanders.
In the novel, his historical Knoxville ladyfriend Sue Boyd fictionally relates the event and his subsequent death and burial. Gen. Burnside promptly named Fort Sanders for him.
So was the Confederate sharpshooter, who used a special rifle (a Whitworth) with a telescopic sight from more than a mile away, also wearing special orange-colored glasses when he did the deed? We’ll probably never know for sure, but Brett Schulte at the TOCWOC blog offers a clue.
“Were these spectacles really used for shooting? Maybe. I’ve looked though civilian texts on rifle shooting and have not found any reference to them before 1880 or so, and most references (which do not specify what the spectacles looked like) are from the turn of the century…Overall conclusion is that the ‘sharpshooter glasses’ seen today are really mass-marketed turn of the century sunglasses, made fully forty years later, and had nothing to do with the Civil War or sharpshooting.”
KNOXVILLE 1863, the novel 
