I wish I had done that with my dad. He died in 1985. He was a B-17 pilot in WWII, andron169 said:
evidently his plane and crew got shot up pretty bad. Really wouldn't talk much about it.
He was mostly quiet about WWII(but I do have pictures and his uniforms). We'd watch
"12 O'clock High" together sometimes and I could tell something was there and see a smile on his face occasionally. Sometimes my dad would mention places they bombed the Hell out of but would never get too specific. I miss him a lot and wish I could have gotten more of that personal stuff but it wasn't to be. I'm proud as can be of my father.
Maybe a campfire or a long drive will do it. Whatever you try, it's all up to him. Let him be himself and let him know you love him and are proud of him. You just want to know about his part in your family. By the way, your description of your dad fits mine.