Every time I read war poetry I start to cry and grow mournful Why?

Hey. Every time I read war poetry, especially war poetry involving soldier's dying and touching war poetry, I begin to get very sad and mournful. I then start to cry.
But, I have a few family members that have served in the military before, but none that were actually K.I.A. or killed or anything. And, they've retired, so their not on active duty.
Why is this? Why do I cry and grow sad every time I read any kind of war poetry?

Most of the poetry I've read is modern, so when it comes to war, it's pretty much about the horrors of war.