But on the same day, on the opposite side of the battlefield, unsung Col. David Ireland and his 137th New York did precisely the same thing.
They call the climactic Confederate attack at Gettysburg "Pickett's Charge" after Virginian George Pickett. But few remember his North Carolina counterpart, James Pettigrew, whose men suffered even more grievously during the terrible attack.
And few know the name of Elizabeth Thorn, a young Gettysburg mother seven months pregnant, who single-handedly buried more than 100 dead soldiers.
These are just a few of the battlefield's forgotten heroes. And with more than 1,400 monuments at Gettysburg, it is impossible to remember them all.
There is the Union commander, George Gordon Meade, whose effective management of the battle takes a backseat in the popular imagination to the debates between Robert E. Lee and his lieutenants.
There is Col. Paul Revere - the grandson of the great patriot - who died leading his men into battle.
There is Capt. Richard Page, the Confederate artillery officer whose battery was cut to pieces on the slopes of Oak Hill because his commander put them in the wrong place.
The 150th anniversary of the great battle is an opportunity for Americans everywhere to remember the forgotten men and women who served and fell at Gettysburg. Across the battlefield, visitors can be seen holding private ceremonies at usually neglected stones, placing flags, wreaths and handwritten notes in memory of these rarely remembered heroes.
Here are a few of their stories:
At the edge of battle
While the crowds packed Little Round Top on Tuesday to remember Chamberlain's deeds, a handful of visitors sought instead the serenity of the now quiet woods on Culp's Hill.
One was David Howell, a 68-year-old Binghamton, N.Y.
Howell used to be a soldier in a re-enactor group made up of descendants of the men in the 137th, but the unit disbanded last year as the members grew too gray.
The 137th was the regiment on the extreme right of the Union army, just as Chamberlain's 20th Maine held the left on the other side of the battlefield.
Most of the Union troops on Culp's Hill had been sent south to reinforce Little Round Top, and Col. David Ireland's 137th was heavily outnumbered. Like the 20th Maine, the 137th bent its line into the shape of a hairpin when it was attacked from three sides. And like Chamberlain, Ireland ordered his men to fix bayonets and charge to drive the Rebels from their front.
"The 137th New York doesn't get the credit of the 20th Maine," Howell said. "If you look at the amount of action by the 20th Maine, it's maybe 20 minutes. The 137th New York was involved in serious fighting in the dark for more than two hours."
And unlike Chamberlain, a professor of rhetoric at Bowdoin College who became governor of Maine, Ireland, who was believed to be a tailor from Scotland, died of dysentery before the war's end.
North Carolina Gen. James Pettigrew was a prominent lawyer before the war. He was a scholar who had graduated from the University of North Carolina at Chapel Hill as a teenager.
When his division commander, Henry Heth, was wounded on the first day of battle, Pettigrew assumed command and helped crack the Union defense on Seminary Ridge.
In two days of fighting, his North Carolinians lost more men than any other Confederate brigade -- 1,450 of the 2,584 who began the battle.
On July 3, Pettigrew commanded one-third of the men in Pickett's Charge, roughly the same number as Pickett himself. But unlike the Virginians, Pettigrew's men had to cross pancake-flat terrain all the way to Union lines, noted Peter Carmichael, Fluhrer professor of history at Gettysburg College.
"He was as important as Pickett," Carmichael said.
Pettigrew was wounded July 14 during the Confederates' retreat into Maryland near Falling Waters. He died July 17, so he wasn't around to defend the legacy of his North Carolina troops.
"There was a flurry of articles and books in the 1880s and if you weren't around to participate in the conversation among magazines, newspapers and books, you counted less in the story," explained Troy Harman, a battlefield park ranger.
Burying the dead
Since 2002, a mysterious bronze woman has stood alone at Evergreen Cemetery under the beating sun.
She holds a shovel and her pregnant belly as she wipes the sweat from her forehead.
Only Gettysburg buffs and tour guides know this is Elizabeth Thorn, who in her third trimester of pregnancy buried about 100 soldiers who died in the battle.
Thorn's great-granddaughter Ruth Angeli returned to the Evergreen Cemetery for the 150th anniversary of the battle to approve plans for a new plaque that will tell the story of her great-grandmother for visitors.
"I'm just like in a daze that this finally transpired," the 90-year-old Angeli said. "We've tried to impress the importance of her contribution to the war, but not a lot of people really know who she was."
The wife of the Evergreen Caretaker, who was off at war, Thorn had no choice but to bury the bodies littering the cemetery.
Angeli has worked over the years to share the story of Thorn's arduous work. She learned some of the details about her great-grandmother from family copies of journal entries Thorn wrote during the war.
After reading an article in a travel edition of National Geographic Magazine discussing the civilians who helped soldiers during the Civil War, Angeli was bothered that women were not mentioned.
"I wrote them a letter about Elizabeth and I thought they would read it and then throw it in a basket somewhere," Angeli said. "I guess they kind of woke up to the fact that women helped, because they actually published it."
Now Angeli hopes to return to Gettysburg from St. Petersburg, Fla., for the dedication of the marker in the months ahead. As she recalled her illustrious ancestor, cemetery visitors stopped to learn the story of the still-unmarked bronze statue.
"I'm so happy to see so many people come by," Angeli said. "No one really knows who she is, but that's why we want to put a plaque somewhere out here explaining."