"(William) never talked much about Wesley after the war," historian John Heiser says. "He always considered him a traitor to his home state. They were literally fighting against each other."
When war amongst the states erupted, family trees fractured as blood relatives, friends and neighbors split along ideological lines.
Border states such as Maryland and Virginia/West Virginia were particularly hit hard, yet schisms also existed in Kentucky and eastern Tennessee.
The Culp family travails are hardly the exception. John Gibbon, a Union commander from North Carolina who fought at Antietam, had three brothers in Confederate uniforms.
Kentucky Sen. John J. Crittendon faced a tougher test. Two sons became major generals during the war: One for the North, the other for the South.
Talking to some of his Shepherd College students not long ago, professor Mark Snell likened the situation to having two brothers, each playing for major college programs, who meet on the football field.
Whom do you root for?
"Take that 1,000 fold and that's what happens in the Civil War," says Snell, director of the George Tyler Moore Center for the Study of the Civil War at Shepherd.
"If you're a sister and you have a brother going off to fight for different sides, who do you pull for?" Snell asks. "You just hope they come back in one piece."
Heiser, historian in the interpretive division of Gettysburg (Pa.) National Military Park, says the hope for many soldiers was not to encounter relatives in battle.
Mitigating that possibility, says National Civil War Museum Director of Education Larry Keener-Farley, is a method of warfare far different from what society is accustomed to in the 21st century.
"Today we think of battle as man fighting man. Because of the mass formations, you were just shooting at sides," he says. "It wasn't quite as personal as war has become. It was very anonymous on the battlefield. Very often you couldn't see the enemy because of the smoke and dust."
Still, Snell says it took years for bonds severed during the war to heal, if they ever did. Many communities and families, like William Culp's, held grudges forever.
Eventually, feelings between North and South were smoothed, and Heiser says soldiers were more apt to reach out for their former opponents than those who hadn't taken part in the fighting.
Joint reunions of Union and Confederate veterans began popping up in the 1880s. Men would assemble on fields they had fought over 20 years earlier and recount stories.
A 50th anniversary reunion at Gettysburg in 1913 led to the resolution creating the Eternal Light Peace Memorial erected in 1938.
"The politicians and the storytellers, the hard feelings are continued for a long time," Heiser says. "The men who were out on the field and saw the death and the dying, they are the ones that said never again should we go through this."
The Civil War was called the War Between the States, but it has also been dubbed the Brothers War, a moniker Heiser says may be most significant.
A student of Civil War history, he says a lot may be learned from what caused families to implode 140 years ago, but also from what brought relatives, friends and neighbors back together in the years after the Confederate Army surrendered at Appomattox Court House in Virginia on April 9, 1865.
"What strikes me most about the reunions is when Union, Confederate veterans get together and walk side by side and show mutual interest and mutual respect. That says a lot," he says. "It's a matter of being proud of the nation and a matter of being proud of our background and resolving that this nation will go on no matter what."