While overseas, Chad A. Caldwell made frequent, short phone calls and used instant messaging to stay close to his family, especially when his wife was expecting their oldest son, Trevor.

“It’s hard to say all you want to in three minutes. You always forget things,” said his wife, Rachael. “But he always talked to Trevor — we put the phone up to my stomach.”

The night Trevor was born, Caldwell called his wife from Baghdad and heard his son’s first loud cry over a cell phone.

Caldwell, 24, of Spokane, Wash., was killed April 30 when a roadside bomb exploded while he was on patrol in Mosul. He was a 2001 high school graduate and was assigned to Fort Hood.

Caldwell joined the Army in 2002, served one tour in Iraq, then a second combat tour in Afghanistan. In February 2007 he signed up for another tour of...