The medically retired Army Reserve first sergeant felt he had to tell his two young daughters, in a way they would understand, about the mental scars that remained more than a decade after his last deployment. He'd deployed twice, nearly back-to-back, with time in both Afghanistan and Iraq, from January 2002 to April 2004.

Those feelings became "Why is Dad So Mad?" — an illustrated 20-page tale featuring a family of lions. Kastle, an instructor at Fort Hays State University in Kansas (about 200 miles west of Topeka), fronted most of the publication costs, then turned to Kickstarter to recoup some cash and raise money for a sequel.

The book is available and listed as a top seller in its category at Amazon.com, and he's been featured on NBC's "Nightly News."

Images from Seth Kastle's book,
Images from Seth Kastle's book, "Why is Dad so Mad?"

Seth Kastle with his oldest daughter, Raegan, age 6.

Photo Credit: Courtesy of Seth Kastle

"This book isn't going to be a fix-it book for everyone," said Kastle, 33. "I just hope it will be good enough to start some conversations."

More from Military Times' Tuesday conversation with Kastle, edited for brevity and clarity:

Q. What made you aware that some of the issues you were dealing with were the result of post-traumatic stress? Was there a particular incident?

A. In the book, I talk about how I feel like it's "a fire inside Dad's chest." I'm by no means an expert in PTSD — or in parenting, for that matter — [but] I can still remember where I was standing, the first time I felt it. I was like, "What is that?" It led to one of 1,000 fights I think my wife [a fellow soldier Kastle met on his first deployment] and I had when we got home. It came and went. As life got more stressful, it came and it got worse. ... I had to get some help, or I was not going to be married anymore.

Q. When did you come up with the idea to do a book, and what was the creative process like?

A. The book is something I had in my head for a couple years. I started to figure out I needed a way to explain this to my daughter. There really is nothing around [as a children's book] for this. ... I had a really bad day at work one day, I sat down and wrote the whole book in about 30 minutes, sitting at my kitchen table. And then it sat there, about six months, eight months. A good friend in the Army kind of lit a fire under me to make this happen for real, so I started to take the steps to find an illustrator, find a publisher, go through the process.

Q. You spoke with female combat veterans while putting together a follow-up book, "Why is Mom So Mad?" [due out later this year]. What did you learn?

A. The first book ... was my experience. It's different than how a woman experiences things. The way I describe anger is different for women. It's different for mothers. It was very beneficial for me to sit down and talk with them ... what it's like dealing with their kids, their spouses. It's not like I took the same story and just changed "Mom" out with "Dad." I made a real effort to make this something that a mother can sit down with her children and talk about this, and it be accurate.

"Why is Dad so Mad?"

"Why is Dad so Mad?" is available online. A sequel is set for later this year.

Photo Credit: Courtesy of Seth Kastle

A. It's everyday life. There's no getting away from it. If there's one thing for sure, it's that parenting is hard. Parenting is hard if you have no obstacles. If you have a short fuse or something, it makes it even harder. When you know you've upset your daughter because you didn't handle a situation the right way, that's a horrible feeling as a parent. When you can look back and go, "That was totally unrealistic of me to react that way in that situation." To go and explain that to a 6-year-old girl, that's tough. That's real tough.

Q. What was your oldest daughter's reaction when she heard the story the first time?

A. I actually kept it from her until it was ready. I had talked about pieces of it with her. My daughter's really sweet — I think everybody's going to say that about their kids, but I really think so, and when I read her the book, she said, "I'm sorry you have the fire in your chest." I'll never forget that. I had talked to her about the fire before, so she knew that that was coming, but I didn't sit down and read the book to my daughter until two, three weeks ago.