"I think they'll be forgotten," Keaveney said of Iraq and Afghanistan veterans. "People get tired of it. It's not glitzy that these are young, honorable, patriotic Americans. They'll just be veterans, and that happens after every war." Keaveney said it's difficult for his group to persuade some homeless Iraq veterans to stay for treatment and help because they don't relate to the older veterans. Those who stayed have had success — one is now a stock broker and another is applying to be a police officer, he said.

"They see guys that are their father's age and they don't understand, they don't know, that in a couple of years they'll be looking like them," he said.

After being discharged from the military, Jason Kelley, 23, of Tomahawk, Wis., who served in Iraq with the Wisconsin National Guard, took a bus to Los Angeles looking for better job prospects and a new life.

Kelley said he couldn't find a job because he didn't have an apartment, and he couldn't get an apartment because he didn't have a job. He stayed in a $300-a-week motel until his money ran out, then moved into a shelter run by the group U.S. VETS in Inglewood, Calif. He's since been diagnosed with post-traumatic stress disorder, he said.

"The only training I have is infantry training and there's not really a need for that in the civilian world," Kelley said in a phone interview. He has enrolled in college and hopes to move out of the shelter soon.

The Iraq vets seeking help with homelessness are more likely to be women, less likely to have substance abuse problems, but more likely to have mental illness — mostly related to post-traumatic stress, said Pete Dougherty, director of homeless veterans programs at the VA.

Overall, 45 percent of participants in the VA's homeless programs have a diagnosable mental illness and more than three out of four have a substance abuse problem, while 35 percent have both, Dougherty said.

Historically, a number of fighters in U.S. wars have become homeless. In the post-Civil War era, homeless veterans sang old Army songs to dramatize their need for work and became known as "tramps," which had meant to march into war, said Todd DePastino, a historian at Penn State University's Beaver campus who wrote a book on the history of homelessness.

After World War I, thousands of veterans — many of them homeless — camped in the nation's capital seeking bonus money. Their camps were destroyed by the government, creating a public relations disaster for President Herbert Hoover.