In February 2010, among Helmand province’s perpetually hot and arid wadis and fields, 22-year-old Nick Rudolph, a Marine infantryman with 1st Battalion, 6th Marine Regiment, was in the middle of a deadly gunfight in Marjah, Afghanistan.

He and his fellow Marines had been fighting Taliban insurgents for hours, when Rudolph caught a glimpse of someone firing at them from around the corner of a mud wall.