SAN ANTONIO – When Chance Darby received the helmet that saved his life in Afghanistan, he said it successfully stopped an enemy rifle bullet but left him with two big headaches. One headache lasted a few days after the impact from a high-velocity round. The other lasted several weeks as he tried to keep the news of the incident from his mother, Lynlee Darby, and his then-fiancée and now wife, Cheryl. Chance proposed to Cheryl shortly before deploying to Afghanistan with the 82nd Airborne Division. On May 31, 2012, Taliban ambushed his platoon while it was dismantling an improvised explosive...