12-pounder Whitworth Rifled Breech-loading Gun

These steel-tubed guns had extremely long range with excellent accuracy, and were imported from England by the Confederacy during the War.

"In Manchester, England, in the late 1850's, Sir Joseph Whitworth patented a system for cannons (and small arms) which used a hexagonal bore design instead of the usual rifling methods. The ammunition also carried the hexagonal design in order to follow the bore, thus allowing for better range and accuracy. Sir Whitworth manufactured his cannons in both breech-loading and muzzle-loading models. "

"There were seven breech-loading and five muzzle-loading 12-pounder (2.75-inch caliber) Whitworth rifled guns in the United States during the American Civil War. During a test trial in Southport Sands, England, in 1863, a 12-pounder breech-loading Whitworth rifle hit a target from 4.7 miles away."
(from Melton)

There were probably only two of these guns at Sharpsburg, both in Confederate batteries.

Find units equipped with these.

Whitworth shell (see a picture at civilwarartillery.com).

2.75 inches

See more about this and other Civil War artillery at the comprehensive Civil War Artillery Page, by Chuck Ten Brink or the very nice Basic Facts page from Jack W. Melton, Jr. The NPS has a fine general introduction to Civil War artillery in a 3-page presentation.