"Equipment providing personal protection from many serious injuries as well as the speed and quality of medical attention have been major factors in saving lives," wrote Marine veteran James Wright, former president of Dartmouth College and author of "Those Who Have Borne the Battle."

In his book, Wright looks at how the odds of surviving battle wounds have changed over the last 250 or so years. During the Revolutionary War there were 1.4 "nonmortal" wounded for every soldier killed in combat. That ratio rose to 2.3 in World War II and 2.6 in Vietnam. The ratio more than tripled in Iraq and Afghanistan, where there are more than seven wounded survivors for every soldier killed.

The predominant use of improvised explosive devices, or IEDs, and rocket-propelled grenades, known as RPGs, in Iraq and Afghanistan has caused an epidemic of amputations and brain injuries. Modern medicine is keeping these soldiers alive, but such catastrophic wounds are difficult and expensive to treat. Many soldiers also become psychologically disabled from post traumatic stress disorder, or PTSD.

Army Sgt. 1st Class Charles Williams suffers from multiple combat injuries. His platoon was ambushed in Afghanistan by Taliban fighters in 2006. An RPG struck and detonated a nearby ammunition box full of Mark 19 grenades, spraying him with shrapnel and throwing him 30 feet into a wall.

Williams said he completed his tour, but was medically retired in 2011 with 100% disability compensation for a brain and shoulder injury, as well as PTSD. While he still has all his limbs, he said that he's incapable of working even a desk job, because of hemiplegic migraines that temporarily paralyze the right side of his body and eliminate his ability to speak.

"Some days, you can look at me and you wouldn't tell there was anything wrong with me," he said. "And then other days, my hands are shaking so bad I look like I have Parkinson's and I can't hardly feed myself."

In addition to Williams' disability compensation, the VA pays his wife, Giovanna, $1,200 monthly to serve as her husband's caretaker. Despite these payments, the couple says they're struggling financially, ever since their house in Leesville, La., was wrecked by a flood in March.

"I'm not looking for no handouts and nothing like that," said Williams, who prior to his injury had been planning to get a job with a high school ROTC program. "A lot of this is kind of embarrassing to me because I can't go to work."

Autry of Disabled American Veterans said the difficult economy has pressured some vets into seeking benefits when they otherwise wouldn't.

"It seems like in periods of economic stress, vets will turn to the VA for health care and other benefits in larger numbers, just like they turn to the military during rough economic times," he said.