After learning of his death, Army Sgt. Chris Davis’ family spent days laughing, crying and remembering the good times — like when they last saw Davis at Christmas.

That last family gathering was like most — loud and fun, with Chris at the center of attention, making jokes and being the loudest of them all, said Margaret Davis, his older sister.

Davis, 35, of Lubbock, Texas, was killed June 23 from an explosive and small-arms fire in Baghdad. He was assigned to Fort Benning, Ga.

The need to serve that led him to enlist in the Army in 1999 started when Davis was little. As a child growing up in Lubbock, he consistently looked for ways to help...