1.5 million fought with the British and 34,000 died. Now their sacrifice in the face of prejudice is being recognised

They were the forgotten voices of the first world war: 1.5 million men, mostly illiterate villagers from northern India, fighting under the command of colonial masters who repaid their bravery and sacrifices with brutality and prejudice.

More Indians fought with the British from 1914 to 1918 than the combined total of Australian, New Zealand, Canadian and South African troops. Some 34,000 Indian soldiers were killed on battlefields in Europe, Africa and the Middle East. But the part they played in the war has been largely whitewashed from history.

Now, just before the 11 November armistice centenary, the last testimonies of the British Empire’s first world war Indian servicemen – 1,000 pages of veteran interview transcripts – have been offered to the British Library.

The first-hand accounts paint a picture of racial segregation and discrimination alongside extraordinary bravery and an awakening hunger for civil rights and independence.

Oral histories were taken from Indian veterans in the 1970s by a team led by DeWitt Ellinwood, an American historian and anthropologist. Transcripts of the recordings have been offered to the British Library by George Morton-Jack, a British historian who traced the material to Ellinwood’s house in upstate New York where it had been stored for decades.

Many of the Hindus, Muslims and Sikhs who served under British command came from poor villages in colonial Punjab and other rural areas. Until now, the best known source on their service has been the letters home from a small proportion of Indian soldiers on the western front, translations of which are held in the British Library and are available online.

The letters – mostly dictated to scribes by illiterate Indian soldiers – were composed in the knowledge that they would be read by censors. “They were careful about what they said. They knew dissent could be punished by the British as their colonial masters. So they habitually held back their true feelings,” said Morton-Jack, the author of The Indian Empire at War.

“But the interviews show they had a strong sense of the racial discrimination they suffered under the British, and their growing belief that they should have civil rights, they shouldn’t be subject to colonial domination, and they should live in their own free country. They describe how those feelings developed through the war,” he said.

Facebook Twitter Pinterest Indian troops are welcomed in Flanders in 1915.

Photograph: Universal History Archive/Getty

Sujan Singh, who was 80 when he was interviewed, said: “We were slaves.” Nand Singh spoke of a “curtain of fear” separating the Indian and white soldiers. They were subject to floggings and other inhumane physical punishment, paid less than their white counterparts, segregated in camps and on trains and ships, denied home leave, and barred from positions of command.

“The British treatment of them was painful in many ways, but at the time they routinely did not speak the truth of their hearts to British power. Their feelings come out in the transcripts,” said Morton-Jack.

Their war service also opened their minds to new ideas about colonial rule. “I felt that Indians should also enjoy freedom like the people of other countries,” said Narain Singh.

Matt Singh, who was 85 when interviewed, said: “When we were in France, we felt the French people were so lucky and were enjoying their freedom. So we also felt that India should be free – this war showed us the right path.”

After the war it took another 30 years before the British Raj ended and India became an independent state. Morton-Jack said: “It’s difficult to overstate how special these transcripts are. There are two messages from these forgotten voices. The negative one is the racial discrimination they suffered. But the positive one is the increasing recognition that the British were denying them civil and political rights and their inner drive for racial equality.”

Over the past four years, British Asians have joined in the centenary commemorations of the first world war, but many feel there should be greater acknowledgement of the role of Indian troops.

“The first world war has traditionally been presented in schools, history books and cinema as a white war. But many in the UK’s British Asian community are saying: we were there too,” said Morton-Jack.

After Ellinwood and his team completed their recordings, he led the mammoth task of transcribing and analysing the content. But he was diverted by other projects, and eventually stored the material at his home in Albany, New York.

Morton-Jack was alerted to their existence by a footnote in one of Ellinwood’s academic articles. By the time he made contact, the US historian was in his 80s and knew he would never complete his work on the Indian veterans.

Ellinwood, who died in 2012, bestowed the transcripts to Morton-Jack with the suggestion that eventually the British Library might take them. Morton-Jack has also discussed the possibility of making them publicly accessible in India. “Ultimately, the transcripts should be available to all, including families of Indian servicemen remembering their part in the war 100 years ago.”

The Indian Empire at War: From Jihad to Victory, the Untold Story of the Indian Army in the First World War by George Morton-Jack is published by Little, Brown (£25). To order a copy for £22 go to guardianbookshop.com or call 0330 333 6846.

• Of the British empire’s colonies, India contributed the most men to the war effort – around 1.5 million – while self-governing nations within the Commonwealth, including Canada, South Africa, Australia, New Zealand and Newfoundland, contributed a further 1.3 million men.

• In proportional terms, New Zealand made one of the largest contributions to the war: 5% of its men aged 15-49 were killed.

• Over 16,000 from the West Indies served, including 10,000 from Jamaica. Others came from Trinidad and Tobago, Barbados, the Bahamas, British Honduras (Belize), Grenada, British Guiana (Guyana), the Leeward Islands, St Lucia and St Vincent.

• At least 180,000 Africans served in the Carrier Corps in east Africa, providing logistics support to the front.