They suffered humiliating discrimination and violence, with many barred from citizenship despite being born in the U.S. But many Chinese-Americans nevertheless fought for America during the Second World War. Yet their valor has never been officially recognized by the U.S. government. A campaign is now underway to change that, as Owen Fairclough reports.

They're fighting for 20,000 Chinese Americans who fought for the U.S. in the Second World War, but have never been honored by congress.

CORKY LEE SON OF CHINESE-AMERICAN WWII VETERAN "The World War Two veterans have always been considered America's 'greatest generation,' but it's basically white."

"They advance on a Jap-held monastery for a final mop-up."

Chinese American troops served with other Asian minorities all over the world, including Japan and the Philippines.

Filipino and Japanese American veterans received a Congressional Gold Medal-the highest civilian honor in the US. But not Chinese Americans. Nearly half of those who signed up were undocumented migrants. They were denied civil rights under so-called "exclusion laws."

OWEN FAIRCLOUGH WASHINGTON DC "The campaign to honor Chinese Americans war veterans in their lifetime is a race against time. It's estimated only up to a thousand of them are still alive."

William Chen was the first Chinese American to become a two-star Major General in the U.S. army. His father a World War Two veteran who supported a famous American fighter squadron in China called the Flying Tigers.

WILLIAM CHEN RETIRED US ARMY GENERAL "They became known and recognized by the American people and that helped open up opportunities for all Chinese Americans and Asian Americans after World War Two."

These campaigners hope their efforts will change perceptions about Asian Americans and answer key questions about their ancestors.

TONY TAGUBA RETIRED US ARMY GENERAL "I got my U.S. citizenship when I was 11 years old and to this day I often get asked if I was in the Philippine Army."

CORKY LEE SON OF CHINESE-AMERICAN WWII VETERAN "The one thing I never got to ask my father - because I guess I was never mature enough to ask him was - 'Why is it that you couldn't become a citizen, you couldn't vote, you couldn't testify in court. Why would you fight for a country, and possibly die, you know, fighting for a country that didn't see you as a possible citizen or even a human being."

Owen Fairclough, CGTN Washington.