After almost nine years of war in Afghanistan and more than seven in Iraq, what compels America's soldiers, sailors, airmen and Marines to return to the combat zones for a fourth, fifth or sixth time?

The simplest answer may be that the military is a calling - in ways unlike any other profession.

"Flying was his life," Gilbert McDowell said of his grandson, Air Force Capt. Mark McDowell, who died in an F-15E crash in Afghanistan on July 18. "He died doing what he wanted to do. He wanted to fly. He was called to fly."

Elida Flores said she begged her grandson, Marine Lance Cpl. Mark Juarez, not to deploy to Afghanistan. "I told him, ‘Don't go. It's too dangerous,' " she said.

"Grandma, I want to go. I volunteered to go," said Juarez, who died in an explosion Jan. 9.

For Hospital Corpsman 3rd Class Benjamin Castiglione, it was all about protecting and caring for his Marines in his role as a combat medic.

"Those Marines meant the world to him," said Carrie Castiglione, after her son was killed by a roadside bomb in Afghanistan on Sept. 3.

Rev. Daniel Swift, giving the eulogy for Army Sgt. Ronnie Kubik, who died of combat wounds in Afghanistan on April 23, put it most succinctly.

Military service, Swift said, "is a mystical power of working for something other than yourself. ... Our world is much safer because there are people like Ron willing to live this life."

Honor the fallen

Honoring those who died in Operations Iraqi Freedom and Enduring Freedom