A minié ball is a lead bullet. They were used in muzzle-loaded rifles. These rifles and bullets could be loaded and fired very quickly. They were also much more accurate at longer distances than any previous weapon. That allowed new war tactics to be developed. Before these weapons came along, soldiers used to line up and fire at each other from only dozens of yards away.
This resource is part of the A State Divided: Exploring the Civil War Through Images collection.