Fellow film lovers and best friends since childhood, John Pacelli and Justin Miller realized their life-long dream of making a movie together after Miller happened upon a community of quirky history hobbyists in their native Illinois.

“Justin was asked to join this group of Civil War reenactors,” Pacelli says. “He didn’t really know what to think, but he went out and bought all this gear, started going to these events. Then he was coming back and telling me about how amazing some of these characters were, how fascinating that culture is.

“In the meantime, it was a particularly interesting time for the community, because it was the 150th anniversary of the war. Justin and I had always joked about making a film together, so we said, hey, let’s do this. It turned into a five-year project, and it only got bigger as we went along.”

As the two men accumulated footage, they narrowed their focus to four participants — two Union enthusiasts and two Confederates — and followed them across a handful of reenactments, including major events at Gettysburg and Appomattox. They also learned a good deal about the weird nerdist obsessions of reenactors — mostly centered around issues of historical authenticity — and about the even weirder intra-cultural divisions those obsessions create.

“You have what they call mainstreamers, who are very serious, and try to be authentic,” Pacelli says. “But they’re not as serious as the campaigners, who take authenticity to the extreme. They won’t eat anything but hardtack; they won’t use the porta-johns; they like to camp miles from the event and march their way in. And then you have the Farbies, guys who don’t care. You’ll see them at the events with coolers, their uniforms hanging out, drinking soda out of a can.

“It was kind of a Catch-22 when we were dealing with the campaigners. They like to talk about what they do, but they don’t like to talk about it with cameras around because it’s not authentic. That was a challenge.”

Pacelli notes that he and Miller made a decision early on to keep their own editorial voices out of the doc, choosing to focus instead on character, on the passion and pathos of their eccentric principles. “You’re not going to convince a hardcore southerner that the war wasn’t about family honor and states rights,” he says. “One guy flat out told me, you’re never going to convince me that I’m wrong and you’re right.

“That’s when I knew we just needed to let these people tell their stories in their own voices. It became in many ways a family-driven documentary. We had an African-American reenactor from Chicago, who had ancestors who were slaves. And we had a reenactor from North Carolina whose grandfather fought for the Confederacy. It just seemed way more important that we hear their voices than that we insert our own voices into the narrative.

“We’re not Civil War scholars, and this is not a Ken Burns project. What we wanted to do was ask, who are these people that do this, and then explore the legacy of the war through what they’re doing now. We let those voices speak, and then let the audience sort it out for themselves.”

The festival premiere of “When to Die” will be Saturday, July 29 at 3 p.m. at Scruffy City Hall.