By John Ostapkovich

PHILADELPHIA (CBS) — Monday marks the 150th anniversary of the beginning of the battle of Gettysburg.

This was the beginning of the beginning of the end, says Richard Goedkoop, Communication professor at La Salle University when he’s not a licensed battlefield tour guide at Gettysburg. North and South collided there, he says, in some ways because of the road network extended from the town-like spokes, but also because General Robert E. Lee had invaded the North for the second time to get the fighting out of Virginia, pillage supplies, relieve the pressure on Vicksburg by diverting Union troops, and maybe scare the North into letting the South secede. It didn’t work, but Goedkoop says it was epic.

“I think, especially at the 150th anniversary we’re commemorating a tremendous amount of courage, heroism and then, in the long-term, reconciliation between the North and the South.”

Gettysburg is about 100 miles west of Philadelphia, and as a tour guide there, Goedkoop says a lot of people he shows around don’t know a whole lot about the battle.

“You have some people who have read a fair amount but have never been there before, or maybe it was only once,” he says, “and then you have a few people who have heard of the battle, know about (Abraham) Lincoln a bit, and heard that Robert E. Lee was here, but don’t know who the commander of the Union Army is, George Meade.”

There were about 50,000 dead and wounded from the 3-day battle before Lee withdrew his forces.