How many degrees of separation?

For a couple years I have heard second or third-hand, of military servicemen and women in combat in Iraq or Afghanistan, usually family or friends of students. I'd catch passing mentions of a guy whose arms were blown off, of a buddy who came home changed, withdrawn, of a middle-aged reservist father getting called up, of a boyfriend being shipped to Iraq, of a friend who bragged about messing up the ragheads.
This semester, the circles are shrinking. I have an Afghanistan vet in one of my classes. Nice guy with a lilting Louisiana drawl, he drove a truck with a civil engineering unit. His unit could be called up again for Iraq duty and he doesn't want to go.
Today, at a college where I work, I learned that the brother of a student was killed by a roadside bomb in Iraq. The degrees of separation collapse steadily, like a death march.