The Imperial War Museum is to use the centenary of the first world war to launch an international appeal for private letters, diaries and photographs held by the families of those who served, with the aim of putting eight million personal stories online by the end of 2018.

The museum's aim is to collect a mass of personal information, much of which will have been stored away in people's cupboards and attics, and make it available to the public at the press of a button. The information submitted and the individual stories of family members will become part of a giant online library for use by historians and people interested in researching their own relatives' roles in the conflict.

The project – called Lives of the First World War and launching next February – will see the museum returning to its founding purpose but adapting to the internet age, in what is believed to be the biggest trawl for historical information ever undertaken. The museum was founded on 5 March 1917, when the War Cabinet approved a proposal by Sir Alfred Mond MP for the creation of a national war museum to record the events still taking place during the Great War and to honour those who had lost their lives and those who survived.

From late 1918, all ration books contained a message appealing for "biographical material, printed or in manuscript form, of all officers and men who have lost their lives or won distinctions". The appeal, printed alongside coupons for margarine and butter, asked for "original letters, sketches, poems and other interesting documents sent from any of the war areas and all kinds of mementoes, even of trifling character".

Material collected went on show in the museum opened in the Crystal Palace, south London, by King George V on 9 June 1920. Almost a century on, the 21st-century equivalent will have a similar purpose, but the digital age will allow a volume of information to be held that would be impossible to store in archives.

Luke Smith, who is in charge of digital for the war's centenary at the museum, said those who sign up with the aim of finding out about relatives or simply researching the war will have a huge resource at their disposal, with links to archives, libraries and other museums.

He believes a huge amount of new information will come to light, partly because many survivors were too traumatised to talk much about their experiences at the time. "Families across the world still hold hundreds of thousands of letters, photos, diaries, postcards, newspaper clippings and other mementoes," Smith said.

"After the war, many participants chose not to discuss their experiences. This was sometimes due to their personal trauma or to the social mores of the time.

"The centenary gives us a period of common focus to ensure those stories are shared.

"At the same time, the ubiquity of the internet combined with lessons learned from platforms such as Facebook, Wikipedia and Flickr allow everyone to collaborate on such a vast project."

New research, published a week before Remembrance Sunday, shows that most British people regret not having done more to record the first world war stories they were told by their families. A YouGov poll of 2,000 people for the autobiography service LifeBook UK found that 64% had had stories about the war related by a parent or grandparent but only 8% had recorded them; 62% of those who had been told stories regretted not having written them down for their children and grandchildren.

For the first few years at least, the Imperial War Museum appeal will just cover Britain and the Commonwealth. "It would be amazing to include the life stories of Germans, Russians, Americans and all other participants," Smith said. However, the museum's remit only covered the Commonwealth countries so that was as far as the project could extend for the time being.

Share your stories

Do you have letters, stories or photographs from any relatives or friends who were involved in the First World War? Whether they were in active service, or in some supporting role at home or abroad, you can tell their story in our GuardianWitness assignment.

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