When Thomas Dyer heads to Afghanistan in December, the former Marine and one-time Southern Baptist pastor won't take a rifle with him. He won't take a Bible, either.

Instead, Dyer, a Tennessean National Guardsman from Memphis and the first Buddhist chaplain in the history of the U.S. Army, hopes to bring serenity and calm, honed by months of intensive meditation.

That preparation, he says, will help him bring spiritual care in the midst of a war zone. "We're going to put it to the test," Dyer said.

Dyer says he's ready for whatever comes. And he believes being knowledgeable about Christianity and Buddhism will make him a better chaplain. Most of all, he wants to be there.

"If I have a Church of Christ or more conservative soldier, he certainly does not need to know about dharma or things like that," he said. "But if he is in pain, or his child back home is sick, I need to be compassionate and help him through that moment. We both need to forget at that moment that I am a Buddhist."

Dyer's deployment is another step in the U.S. military's attempt to meet the diverse spiritual needs of America's fighting forces. It's no easy task.

For one thing, the military chaplaincy is facing all the complications that have affected American religion over the past 40 years. The decline of mainline Protestants and their aging clergy. The ongoing Catholic priest shortage. The explosion of religious diversity. The emergence of people with no faith. The ease with which people move from one faith to another.

The military is trying to adapt to these changes, while trying to find ministers willing to serve in a war zone, and who can minister to American troops without offending Muslim allies.

Military chaplains have cared for the souls of American troops since at least the 1700s. In 1775, the Continental Congress agreed to pay chaplains $20 a month. Gen. George Washington told his commanders to find chaplains of good character and exemplary lives to care for the souls of their troops.

The first chaplains served a mostly Protestant military. Chaplains today serve in a remarkably diverse environment.

The latest report from the Defense Department tracks 101 faiths for active-duty personnel, from 285,763 Roman Catholics to the one member of the Tioga River Christian conference. In between are Baptists, Jews, Buddhists, Baha'is, Mormons and Wiccans. About a half a million active personnel are evangelicals. Almost 281,710 claim no religion.

No military has ever tried to meet such diverse spiritual needs, says Doris Bergen, a history professor at the University of Toronto. In World War II, the British army had thousands of Hindus and Muslims in its ranks, but only Christian and Jewish chaplains.

"To build a military chaplaincy that reflects the incredible religious diversity of Americans, and that supports that diversity in a meaningful way — it's uncharted terrain," Bergen said. "It's completely brand new. You don't really have any models to look to."

That means chaplains like Maj. Darin Olson at Fort Campbell maintain a delicate balance.

In chapel services, he's a Nazarene minister. That means preaching about Jesus. Once services are over, he becomes an advocate for every faith group.

"I am here to guarantee the religious freedom of every soldier," Olson said.

Chaplains and their assistants also serve as a listening ear for soldiers, as they deal with stress.