A new report has found "pervasive racism" underpinned a failure to properly commemorate potentially hundreds of thousands of predominantly black and Asian service personnel who fought for the British Empire.
The Commonwealth War Graves Commission (CWGC) has apologised after its investigation found that those individuals were not formally remembered in the same way as their white comrades.
The CWGC investigation, which focused on when the organisation was known as the 'Imperial War Graves Commission' (IWGC) and found that at least 116,000 predominantly African and Middle Eastern First World War casualties "were not commemorated by name or possibly not commemorated at all".
It also suggested between 45,000 and 54,000 Asian and African casualties were "commemorated unequally".
Some were commemorated collectively on memorials and others, who were missing, were only recorded in registers rather than on stone.
Defence Secretary Ben Wallace apologised on behalf of the Government and CWGC for the "failures to live up to their founding principles all those years ago", and told the House of Commons of his "deep regret" over the time taken to rectify the situation.
"Whilst we can’t change the past, we can make amends and take action," he said.
Mr Wallace added there "can be no doubt" that prejudice played a part in some of the decisions made by the commission.
He said "it is hardly surprising that mistakes were made" in identifying those who died, due to "pressures and confusion" of war, but stated: "What is surprising and disappointing, however, is that a number of the mistakes, the number of casualties commemorated unequally, the number commemorated without names and the number otherwise entirely unaccounted for is not excusable.
"In some cases, the IWGC assumed that communities of forgotten personnel would not recognise or value individual forms of commemoration.
Watch: The Defence Secretary gave his apology in the House of Commons.
"In other cases, they were simply not provided with the names or burial locations.
"I feel it is my duty as a former soldier to do the right thing by those who gave their lives in the First World War across the Commonwealth and take what necessary steps we can to rectify the situation," Mr Wallace continued.
The special committee behind the investigation was established by the CWGC in 2019, in response to a documentary presented by David Lammy called 'Unremembered'.
The investigation found that the failure to properly commemorate the individuals was "influenced by a scarcity of information, errors inherited from other organisations and the opinions of colonial administrators".
"Underpinning all these decisions, however, were the entrenched prejudices, preconceptions and pervasive racism of contemporary imperial attitudes."
In its response to the report, the CWGC said it "acknowledges that the commission failed to fully carry out its responsibilities at the time and accepts the findings and failings identified in this report and we apologise unreservedly for them".
Prime Minister Boris Johnson said: "During the First World War, millions of people from Africa, Asia, the Caribbean and the Middle East fought for Britain in the struggle against tyranny.
"Their contribution to victory was immense, not just in numerical terms but in their courage and valour, and many paid the ultimate price so that we might live in peace and freedom today.
"I am deeply troubled by the findings of the Special Committee that not all of our war dead were commemorated with equal care and reverence. On behalf of the Government, I offer an unreserved apology.
"I welcome the fact that the Commonwealth War Graves Commission has accepted all of the Committee's recommendations and that it will now re-examine records and make amends wherever possible.
"Our shared duty is to honour and remember all those, wherever they lived and whatever their background, who laid down their lives for our freedoms at the moment of greatest peril."
In a statement, CWGC director general Claire Horton said: "The events of a century ago were wrong then and are wrong now.
"We recognise the wrongs of the past and are deeply sorry and will be acting immediately to correct them."
Shadow justice secretary Mr Lammy said the findings and apology offered now create an opportunity to deal with this "ugly part of history".
"No apology can ever make up for the indignity suffered by the unremembered," he said.
"However, this apology does offer the opportunity for us as a nation to work through this ugly part of our history – and properly pay our respects to every soldier who has sacrificed their life for us."