The Union artillery class of siege and garrison was determined by pieces that could be moved on carriages by road, to form the siege train of an army. The 24-pounder smoothbore model of 1839 was among the heaviest pieces.

This set depicts men of the heavy artillery in full dress uniforms worn on campaign early in the Civil War. All wear the regulation Hardee hat and brass shoulder scales. Two men carry trail spikes, to prop each side of the rear gun carriage, and lever the gun back into position after firing. Between 1861 and 1866 the Federal Ordinance Department purchased a total of 677 siege guns.