All of my biological great-grandfathers had something to do with WWII.
"Pops" was infantry in U.S. Army, had awesome (and downright scary) stories.
"Grandpa Babe" was in the Navy or Marines or something, forgot which. I never have even seen him, and he died already.
"Grandpa Arnold" was in the Air Force, and air lifted supplies to Berlin. He's also my ancestral link to Benedict Arnold, Oliver Hazard Perry, George W. Bush, and other people.
"Grandpa Bob" was in the Navy I'm pretty sure.