Some will, srted flyig.ome wont.
I agree. I have seen it happen in combat in Iraq and Afg. Some of the most timid, soft people I've ever met fought fiercely and helped maintain their ground. While others cowered in the vehicles or behind the nearest structure.
That's exactly what my son told me. He was XO of a National Guard battalion in Iraq that saw more action than many regular Army units. Said it was very hard to predict, but he had little respect for troops that were "operators" etc." in civilian life, saw some fall apart when the metal started flying. Could just as likely be the scared skinny kid who comes through when the SHTF.
