Sometimes, and this seems more like a crutch than anything, it can be the type of work he is into. Some people who are (ex-)military, police, corrections officers, etc, develop those kinds of habits and are extremely abusive and very drill-instructor about what goes on in their lives. On the other hand, it sounds like he is an alcoholic.
Alcoholics most times than not are very violent physically and/or mentally towards their spouse or family. Alcoholism isn't that persons fault, its a disease. Their brain cant "operate" without alcohol, or so it thinks.
And based on what you said about him and his whiskey, I kind of think that is what you're dealing with. Trust me on this, you do NOT want to confront someone who is an active or dormant alcoholic about their problem. My dad is a recovering alcoholic and this is how he treated my mom and I until he went to rehab.
Even though he has been sober and "dry" for two years now after a relapse, he is still very disconnected from my mom and I. But when we would always try to ask him about it, he would go ballistic on us. It took him almost dying from alcohol poisoning to get him to realize he needed rehab.
Sooo to sum it, possibly job aspect but I'm thinking alcoholic. Or could be a combination of both because they feed into each other. I hope this helps a little bit and maybe you can talk to your mom about what it could be.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.