"If you are any kind of history buff, this is the key day of the war," said Matt Knox, 54, of Bedford, Va, during the Wednesday re-enactment on the 150th anniversary of the battle.
In July 1863, some 12,000 Confederate troops marched a mile under heavy fire from 8,000 troops, ending in disaster for the South.
In just an hour, 6,500 soldiers were dead, wounded, captured or missing in Picketts' Charge. About 51,000 soldiers died in the three days of fighting at Gettysburg.
Kevin Farrar, a Confederate re-enactor from Lovettsville, Va., told USA Today it was "mind-boggling" to think of the conditions of that mile-long march.
"It's like the beaches of Normandy," he said.
The Wednesday re-enactment is part of 10 days of events celebrating the 150th anniversary of the Civil War in Gettysburg, which began Friday and will end Saturday, USA Today said.
About 200,000 visitors are expected to pass through Gettysburg during the 10-day span and spend about $100 million.