Nearly 1 million Indian troops fought for the British Empire in Europe and Mesopotamia during the conflict.

But some veterans believe the role played by volunteers from India and the rest of the Empire in both world wars is relatively unknown.

In World War I alone, more than 50,000 Indians died fighting for Britain.

Jim Fish reports on the Empire's unsung heroes

During World War II much of north-east India was turned into a British military camp to defend south-east Asia from the advancing Japanese army.

Voluntary enlistment in the Indian Army - under British command - was stepped up. By the end of the war it became the largest volunteer army in the world - and played a decisive role in ending the war.

Dr Kusoom Vadgama, who is campaigning for greater public recognition of India's role, says that Indian soldiers paid a price for British freedom.

"It's about time that we were put into text books and children's history books, so that we can live in the country with some degree of dignity," she says from her surgery in north London.

Largest volunteer army in history

Harbans Singh - one of about 2.5 million Indian soldiers who enlisted for Britain in World War II - says martial traditions came before any misgivings about fighting for someone else's King and country.

"We were not fearing from war. Our mind became like theirs. We thought: 'If we will not kill this man, he will kill us'," he says.

Captured by the Germans, he survived both German prison camp and the experience of being bombed by his own side on the way there.

At the end of the war he lived to fight in the new army of independent India against Pakistan and China.

Dr Kusoom Vadgama has a collection of letters written by Indian soldiers who fought for Britain.

"Some talk about how hell might be better than this bitter sickening period of their time in England.

"But yet they always said at the end of the letter that they must stick with their King and Emperor," she says.

In 1944, Indian forces were largely responsible for recapturing Burma and stopping the Japanese advance on the rest of the Raj.