The family invited McMillan into their Philadelphia home and what he found there went way beyond the flag. 

"I went to the bathroom in their home and I came down their stairs and I saw some things on the wall where you hang high school diplomas and things like that. And these items were signed by John Adams, Thomas Jefferson, and James Madison," McMillan recalled. "They were George Armistead's original army commissions. And I said, 'You can't have these in your house!'"

They also had an original portrait of the Commander. McMillan was able to connect them with the Smithsonian where they've since donated many of these national treasures. 

McMillan says he loved digging into the research for this book. 

"I think to do it you have to love the research just as much as the writing," he explained. "Writing is fun, but it's learning. If you weren't curious like sometimes people will come up – this is my fourth book – 'why don't you write about this, why don't you write about that.' You have to love it. You can't just get an assignment."

For him, this was no "assignment." 

Before writing this book, he served as Vice President of Communications for the NHL's Pittsburgh Penguins. 

"I had a great career," he said. "I was in the media before that but I always said that, you know, for a lot of people sports is their escape from their job so when you work in sports you need an escape from it so history was my 'sports.'" 

He says his hope for this book is that it deepens readers' appreciation for history – and our country. 

"One of the curators said when we were working on it the last time that they viewed it as a metaphor for the country," he said. "It's tattered, it's torn but it still survives and the flag survives if the country survives."