feels mortar

“Hopefully, you won’t have to,” I said. “You don’t need to fight so much as survive for a little wh—”
My head snapped back as a sledgehammer swung by someone on a speeding train hit me right in the middle of my forehead. I staggered.
One of my volunteers fell from his position. Pretty much all that was left of his head was his mouth and jaw.
“Down!” Sanya screamed. “Heads down!”
Then we heard a number of hollow booms. And, a second later, a chorus of whistling sounds.
“Mortars,” Sanya snarled. “Incoming! Everyone down!”

Battle Ground Chapter 26, Page 242-243