Twelve thousand five hundred young men from North Carolina, Georgia, Virginia, Mississippi, Louisiana, Florida in a line a mile wide stepped out from the tree line you see across this field and began to march 3/4 of mile toward the Union line.
If you could cover a yard in one step and a step in one second -- under cannon fire -- it would take you 22 minutes to traverse this distance. The battle lasted just over a half-hour.
As the Rebel forces got nearer, Federal cannoners changed from exploding shells to grape shot, firing double and triple canisters.
At 200 yards musket fire was reliably lethal; at 50 yards they were reliably accurate.