A large stash of vivid, unpublished Civil War drawings is on display in Boston. Unfortunately, they are illegible in this news story. The museum site offers better views and the 650-picture collection has its own site. Best is the browse-by-subject page.
Shown above: detail from McClellan's Laurel Hill pursuit of Garnett. The on-the-scene artist wrote, "Raining in torrents. Mud over ankles. Men worn out. At first cannon shot they waked up and at every shot quickened their steps till the[y] came in leaning forward and going double quick. Military stores of all description scattered on the road."