ignored the postcards and telephone messages asking if he would be willing to volunteer for active duty to "backfill" somewhere on the East Coast, Europe or Hawaii. That would be OK, he thought. It would release active duty oral surgeons from those areas to go to combat zones in Iraq or Afghanistan.

But then the orders came for him to go to Afghanistan.

Today, Caulfield, a colonel from Satellite Beach, Fla., is an example of how the continuing demands of keeping ground troops in Afghanistan and Iraq are forcing the military to go to extraordinary measures to keep its ranks filled. He's attending to patients - U.S. troops, Afghan soldiers and civilians - at the Army's 325th Field Hospital in Bagram, Afghanistan.

He is one of about 100 over the age of 60 known to be serving. The Department of Defense couldn't provide exact figures.

Lt. Col. Bryan Hilferty, an Army spokesman, said the service has taken back some 350 soldiers who had already retired from the military. But some of those could have done 20 years of duty and still be only in their late 30s. He did not know how many of the returning retirees are 60 or older.

The reason, he said, is clear: "It's the continuing demand in the service."

The Navy has 36 medical personnel and 16 chaplains who are over 60.

There is one Marine between 60 and 65 currently serving.

The Air Force has 12 chaplains over 60 and 32 medical personnel between 60 and 65.

"The rules say it's at 60 years of age when people retire," said Dov Schwartz, an Army spokesman. The Army will issue waivers allowing people who are older to serve if they have needed skills. Returning, though, is "totally voluntary," Schwartz said.

Caulfield has much-needed experience in gunshot and fragmentation injuries.

"We salute his courage," Schwartz said. "We salute his bravery."

Caulfield lived and practiced oral surgery in Salisbury, N.C., before moving to Satellite Beach two years ago.

When the call came, he had no qualms about serving. He said that because the wars in Afghanistan and in Iraq were within such a close time, the military is exhausting some specialties. They have rotated some reservists in and out.

"Because there is no draft, they are using and maybe overusing the National Guard and Reserve," he said. "There is no obligatory method."

Caulfield said he is glad to be able to help.

"I've been a soldier for 25 years," he said. "When your country asks, you do it."

His wife of 47 years, Patricia, said she thought a cruise through the Panama Canal they took after he gave up his private practice would be the most adventurous experience they would have after retirement.

"I feel a lot more comfortable than when he was in Vietnam," she said. "This is a great way to finish his career."

Getting ready involved updating his medical credentials and re-establishing military security clearances. His pre-deployment preparation at Fort Benning, Ga., included making sure he was physically fit and could use a gun. Caulfield carries a gun in a holster strapped to his side, sometimes under his scrubs.

"Getting used to wearing boots and carrying a gun is a little unusual," he said.

But the habits of an old soldier didn't fade away.

"Readjusting to the Army was a lot like riding a bicycle again after 24 years: a little rocky at first, but you make adjustments and it comes back to you," he said.

--------------------------------------------------------------------------------