GETTYSBURG, Pa. — The booms of ground-rattling cannon fire Monday marked the ceremonial start of the Battle of Gettysburg, 150 years to the day after Union and Confederate troops fought the defining encounter of the Civil War.

But instead of sabre-carrying soldiers, tourists and history buffs are now swarming the battlefield in this small, south-central Pennsylvania town to commemorate the milestone anniversary of the three-day battle.

Little Round Top figures to be one of the most popular destinations Tuesday. No place in Gettysburg has become more popular to visit in recent years than the hill desperately defended by the 20th Maine Regiment on July 2, 1863 — Day 2 of the three-day encounter — in one of the key moments that ultimately led to Union victory.

Thank a Pulitzer-Prize winning novel, a Ken Burns documentary and Hollywood for turning the Maine soldiers and its commander, Col. Joshua Lawrence Chamberlain, into Civil War stars 150 years later.

Chamberlain said, “Bayonets!” 6-year-old Luke Johnson recounted with a yell as he held a toy rifle above his head as if he were swinging around a sword. He was acting out a scene from the 1993 movie “Gettysburg,” in which Chamberlain was played by actor Jeff Daniels

Luke’s mother, Wendi, 39 of Carterville, Ill., said Luke and his 5-year-old brother Andrew had been watching the PG-rated film every day in the weeks leading up to their vacation to Pennsylvania. Andrew “gets upset when I try to turn the movie off. He says ‘The battle’s not over, Mom,” Wendi Johnson said with a laugh. “I say, ‘You know how it ends!'”

Burns’ seminal 1990 documentary about the Civil War also looked at Chamberlain. The 1974 novel, the “Killer Angels” by Michael Shaara inspired the movie “Gettysburg.”

The movie has had an influence on some history buffs who decided to take up the hobby of re-enacting. When asked, Pennsylvania Gov. Tom Corbett called Chamberlain his favorite figure who emerged from Gettysburg.

“The Civil War came on in some respects for troops on both sides so quickly, and so many people had to become leaders so quickly,” Corbett said during a news conference for the opening Monday of the Seminary Ridge Museum, Gettysburg’s newest attraction. “If you think of the story of Joshua Chamberlain and had the opportunity to read the “Killer Angels” and what he went through, he became my favorite.”

It’s no surprise, then, that the stone step path that lead to the memorial to Maine soldiers has been replaced with a paved walkway to easily ascend the hill, just in time for anniversary week. While the National Park Service doesn’t keep official statistics by battlefield sights, the paving is a clear sign of Little Round Top’s popularity.

The short story of Chamberlain and his men goes like this: In a desperate move to hold the Union’s left flank, Chamberlain’s regiment was ordered on the hill and placed at the end of a line shaped like a fishhook. Troops from Alabama trying to take the hill were repulsed several times, but the Maine soldiers were running out of ammunition. Chamberlain ordered a bayonet charge down the hill that secured victory.

The account never really gained acclaim until Shaara’s book and later the documentary and movie. There are disputes over the details, but Chamberlain’s accounts have become prevalent in part because he later went on to become Maine’s governor, said Peter Carmichael, history professor at Gettysburg College.

It was Chamberlain, as brigadier general, who formally received the Confederate surrender at Appomattox in 1865.

“Before the book and the movie, there wasn’t even a trail to the 20th Maine monument,” Carmichael said. “The bottom line is, Chamberlain wanted us to see him in a certain way, and that’s exactly what we’ve done. He wanted his heroics to be seen a certain way.”

Shaara died in 1988. His son, Jeff, himself a bestselling author whose “Gods and Generals” was the 1996 prequel to his father’s classic, said the “Killer Angels” was a “good story … it’s not a history of the Battle of Gettysburg.”

“What he does is tell you a story of one of the characters of that story,” Jeff Shaara said this weekend during a book signing in Gettysburg. “You don’t have to be a Civil War buff. … People don’t have to know anything that goes on historically. They just get caught up in the drama.”