It seems an odd enthusiasm for a guy who almost never spoke about his military service when we kids were growing up. I know the wars in Iraq and Afghanistan distress him, as did the Vietnam war. And his frequent visits to the VA for medical treatment probably keep them in the forefront of his mind.
But when I finally asked him, "Why all the books?" he described the war not as an obsession but as a random kind of interest. He said that as he's gotten older, his mind is like the Sargasso Sea, filled with bits of floating garbage. Sometimes the bits wash together and form a mass, a garbage island, and when that happens, occupying more and more space in his mind, he starts to pick through it, and uses his scavengings to form complete thoughts.
I understand completely.